Easy Book SIEMENS_S7_1200_KTP400_BASIC_STARTERKIT Ver. 01 197349 An En SIEMENS S7 1200 KTP400 BASIC STARTERKIT

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Easy Book

___________________
Preface
Introducing the powerful and
1
___________________
flexible S7-1200

SIMATIC
S7-1200
Easy Book

STEP 7 makes the work
2
___________________
easy

3
___________________
Getting started

___________________
4
PLC concepts made easy
Easy to create the device
___________________
5
configuration

Manual

___________________
6
Programming made easy
Easy to communicate
___________________
7
between devices

___________________
8
PID is easy
Web server for easy Internet
___________________
9
connectivity

___________________
10
Motion control is easy
___________________
11
Easy to use the online tools
___________________
12
IO-Link is easy
___________________
A
Technical specifications
Exchanging a V3.0 CPU for
___________________
B
a V4.0 CPU

03/2014

A5E02486774-AF

Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent
damage to property. The notices referring to your personal safety are highlighted in the manual by a safety alert
symbol, notices referring only to property damage have no safety alert symbol. These notices shown below are
graded according to the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
indicates that minor personal injury can result if proper precautions are not taken.
NOTICE
indicates that property damage can result if proper precautions are not taken.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will
be used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to
property damage.

Qualified Personnel

The product/system described in this documentation may be operated only by personnel qualified for the specific
task in accordance with the relevant documentation, in particular its warning notices and safety instructions.
Qualified personnel are those who, based on their training and experience, are capable of identifying risks and
avoiding potential hazards when working with these products/systems.

Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended
or approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and
maintenance are required to ensure that the products operate safely and without any problems. The permissible
ambient conditions must be complied with. The information in the relevant documentation must be observed.

Trademarks

All names identified by ® are registered trademarks of Siemens AG. The remaining trademarks in this publication
may be trademarks whose use by third parties for their own purposes could violate the rights of the owner.

Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software
described. Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the
information in this publication is reviewed regularly and any necessary corrections are included in subsequent
editions.

Siemens AG
Industry Sector
Postfach 48 48
90026 NÜRNBERG
GERMANY

Order number: 6ES7298-8FA30-8BQ0
Ⓟ 12/2013 Technical data subject to change

Preface
Welcome to the world of S7-1200. The SIMATIC S7-1200 compact controller is the modular,
space-saving controller for small automation systems that require either simple or advanced
functionality for logic, HMI and networking. The compact design, low cost, and powerful
features make the S7-1200 a perfect solution for controlling small applications.
As part of the SIMATIC commitment to "totally integrated automation" (TIA), the S7-1200
product family and the TIA Portal programming software give you the flexibility you need to
solve your automation needs.
The S7-1200 helps to make the most challenging tasks easy!
The SIMATIC S7-1200 controller solution, designed for the "compact" controller class, is
comprised of the SIMATIC S7-1200 controller and SIMATIC HMI Basic panels that can both
be programmed with the TIA Portal engineering software. The ability to program both
devices using the same engineering software significantly reduces development costs. The
TIA Portal includes STEP 7 for S7-1200 programming and WinCC for designing Basic panel
projects.
The S7-1200 compact controller includes:
• Built-in PROFINET
• High-speed I/O capable of motion control, onboard
analog inputs to minimize space requirements and
the need for additional I/O, 4 pulse generators for
pulse-train and pulse-width applications (Page 67) ,
and up to 6 high-speed counters
• On-board I/O points built into the CPU modules
provide from 6 to 14 input points and from 4 to 10
output points.
Signal modules for DC, relay, or analog I/O
expand the number of I/O points, and
innovative signal boards snap onto the front
of the CPU to provide additional I/O
(Page 18).
The SIMATIC HMI Basic panels (Page 22)
were designed specifically for the S7-1200.
This Easy Book provides an introduction to
the S7-1200 PLC. The following pages offer
an overview of the many features and
capabilities of the devices.

For additional information, refer to the S7-1200 programmable controller system manual. For
information about UL and FM certification, CE labeling, C-Tick and other standards, refer to
the Technical specifications (Page 281).

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Preface

This manual describes the following products:
● STEP 7 V13 SP1 Basic and Professional
● S7-1200 CPU firmware release V4.0

Documentation and information
S7-1200 and STEP 7 provide a variety of documentation and other resources for finding the
technical information that you require.
● The S7-1200 system manual provides specific information about the operation,
programming, and the specifications for the complete S7-1200 product family. In addition
to the system manual, the S7-1200 Easy Book provides a more general overview to the
capabilities of the S7-1200 family.
Both the system manual and the Easy Book are available as electronic (PDF) manuals.
The electronic manuals can be downloaded from the customer support web site and can
also be found on the documentation disk that ships with every S7-1200 CPU.
● The online STEP 7 information system provides immediate access to the conceptual
information and specific instructions that describe the operation and functionality of the
programming package and basic operation of SIMATIC CPUs.
● My Documentation Manager accesses the electronic (PDF) versions of the SIMATIC
documentation set, including the system manual, the Easy Book, and the STEP 7
information system. With My Documentation Manager, you can drag and drop topics from
various documents to create your own custom manual.
The customer support entry portal (http://support.automation.siemens.com) provides a
link to My Documentation Manager under mySupport.
● The customer support web site also provides podcasts, FAQs, and other helpful
documents for S7-1200 and STEP 7. The podcasts utilize short educational video
presentations that focus on specific features or scenarios in order to demonstrate the
interactions, convenience, and efficiency provided by STEP 7. Visit the following web
sites to access the collection of podcasts:
– STEP 7 Basic web page (http://www.automation.siemens.com/mcms/simaticcontroller-software/en/step7/step7-basic/Pages/Default.aspx)
– STEP 7 Professional web page (http://www.automation.siemens.com/mcms/simaticcontroller-software/en/step7/step7-professional/Pages/Default.aspx)
● You can also follow or join product discussions on the Service & Support technical forum
(https://www.automation.siemens.com/WW/forum/guests/Conferences.aspx?Language=e
n&siteid=csius&treeLang=en&groupid=4000002&extranet=standard&viewreg=WW&nodei
d0=34612486). These forums allow you to interact with various product experts.
– Forum for S7-1200
(https://www.automation.siemens.com/WW/forum/guests/Conference.aspx?SortField=
LastPostDate&SortOrder=Descending&ForumID=258&Language=en&onlyInternet=Fa
lse)
– Forum for STEP 7 Basic
(https://www.automation.siemens.com/WW/forum/guests/Conference.aspx?SortField=
LastPostDate&SortOrder=Descending&ForumID=265&Language=en&onlyInternet=Fa
lse)

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Preface

Service and support
In addition to our documentation, Siemens offers technical expertise on the Internet and on
the customer support web site (http://www.siemens.com/automation/).
Contact your Siemens distributor or sales office for assistance in answering any technical
questions, for training, or for ordering S7 products. Because your sales representatives are
technically trained and have the most specific knowledge about your operations, process
and industry, as well as about the individual Siemens products that you are using, they can
provide the fastest and most efficient answers to any problems you might encounter.

Security information
Siemens provides automation and drive products with industrial security functions that
support the secure operation of plants or machines. They are an important component in a
holistic industrial security concept. With this in mind, our products undergo continuous
development. We therefore recommend that you keep yourself informed with respect to our
product updates. Please find further information and newsletters on this subject at:
(http://support.automation.siemens.com)
To ensure the secure operation of a plant or machine it is also necessary to take suitable
preventive action (e.g. cell protection concept) and to integrate the automation and drive
components into a state-of-the-art holistic industrial security concept for the entire plant or
machine. Any third-party products that may be in use must also be taken into account.
Please find further information at: (http://www.siemens.com/industrialsecurity)

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Preface

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Table of contents
Preface ................................................................................................................................................... 3
1

Introducing the powerful and flexible S7-1200 ....................................................................................... 15
1.1

Introducing the S7-1200 PLC.......................................................................................................15

1.2

Expansion capability of the CPU..................................................................................................18

1.3

S7-1200 modules .........................................................................................................................21

1.4

Basic HMI panels .........................................................................................................................22

1.5

Mounting dimensions and clearance requirements .....................................................................23

1.6

New features ................................................................................................................................27

STEP 7 makes the work easy ............................................................................................................... 29
2.1

Easy to insert instructions into your user program.......................................................................30

2.2

Easy access to your favorite instructions from a toolbar .............................................................30

2.3

Easy to add inputs or outputs to LAD and FBD instructions ........................................................31

2.4

Expandable instructions ...............................................................................................................31

2.5

Easy to change the operating mode of the CPU .........................................................................32

2.6

Easy to modify the appearance and configuration of STEP 7 .....................................................33

2.7

Project and global libraries for easy access ................................................................................33

2.8

Easy to select a version of an instruction ....................................................................................34

2.9

Easy to drag and drop between editors .......................................................................................34

2.10

Changing the call type for a DB ...................................................................................................35

2.11

Temporarily disconnecting devices from a network .....................................................................36

2.12

Easy to virtually "unplug" modules without losing the configuration ............................................37

Getting started ...................................................................................................................................... 39
3.1

Create a project............................................................................................................................39

3.2

Create tags for the I/O of the CPU ...............................................................................................40

3.3

Create a simple network in your user program ............................................................................41

3.4

Use the PLC tags in the tag table for addressing the instructions ...............................................43

3.5

Add a "box" instruction .................................................................................................................44

3.6

Use the CALCULATE instruction for a complex mathematical equation .....................................45

3.7

Add an HMI device to the project .................................................................................................47

3.8

Create a network connection between the CPU and HMI device ................................................48

3.9

Create an HMI connection to share tags .....................................................................................48

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3.10

Create an HMI screen ................................................................................................................. 49

3.11

Select a PLC tag for the HMI element ........................................................................................ 50

PLC concepts made easy ..................................................................................................................... 51
4.1

Tasks performed every scan cycle ............................................................................................. 51

4.2

Operating modes of the CPU ...................................................................................................... 52

4.3
4.3.1
4.3.2
4.3.3

Execution of the user program .................................................................................................... 53
Processing the scan cycle in RUN mode .................................................................................... 54
OBs help you structure your user program ................................................................................. 55
Event execution priorities and queuing ....................................................................................... 55

4.4
4.4.1
4.4.2
4.4.3
4.4.4

Memory areas, addressing and data types ................................................................................. 58
Data types supported by the S7-1200 ........................................................................................ 60
Addressing memory areas .......................................................................................................... 62
Accessing a "slice" of a tagged data type ................................................................................... 64
Accessing a tag with an AT overlay ............................................................................................ 65

4.5

Pulse outputs .............................................................................................................................. 67

Easy to create the device configuration ................................................................................................. 71
5.1

Detecting the configuration for an unspecified CPU ................................................................... 72

5.2

Adding a CPU to the configuration .............................................................................................. 73

5.3

Changing a device ...................................................................................................................... 74

5.4

Adding modules to the configuration ........................................................................................... 74

5.5
5.5.1

Configuring the operation of the CPU and modules ................................................................... 76
System memory and clock memory provide standard functionality ............................................ 77

5.6

Configuring the IP address of the CPU ....................................................................................... 80

5.7
5.7.1
5.7.2

Protecting access to the CPU or code block is easy .................................................................. 82
Know-how protection ................................................................................................................... 84
Copy protection ........................................................................................................................... 85

Programming made easy ...................................................................................................................... 87
6.1
6.1.1
6.1.2
6.1.3
6.1.4
6.1.5
6.1.6

Easy to design your user program .............................................................................................. 87
Use OBs for organizing your user program ................................................................................ 89
FBs and FCs make programming the modular tasks easy ......................................................... 90
Data blocks provide easy storage for program data ................................................................... 92
Creating a new code block .......................................................................................................... 92
Creating reusable code blocks .................................................................................................... 93
Calling a code block from another code block ............................................................................ 94

6.2
6.2.1
6.2.2
6.2.3
6.2.4

Easy-to-use programming languages ......................................................................................... 94
Ladder logic (LAD) ...................................................................................................................... 94
Function Block Diagram (FBD) ................................................................................................... 95
SCL overview .............................................................................................................................. 96
SCL program editor ..................................................................................................................... 96

6.3
6.3.1
6.3.2
6.3.3

Powerful instructions make programming easy .......................................................................... 98
Providing the basic instructions you expect ................................................................................ 98
Compare and Move instructions ............................................................................................... 100
Conversion instructions ............................................................................................................. 101
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6.3.4
6.3.5
6.3.6
6.3.7

Math made easy with the Calculate instruction .........................................................................103
Timers ........................................................................................................................................104
Counters .....................................................................................................................................109
Pulse-width modulation (PWM) ..................................................................................................111

6.4

Easy to create data logs ............................................................................................................112

6.5
6.5.1
6.5.2
6.5.3
6.5.4
6.5.4.1
6.5.4.2

Easy to monitor and test your user program ..............................................................................114
Watch tables and force tables....................................................................................................114
Cross reference to show usage .................................................................................................115
Call structure to examine the calling hierarchy ..........................................................................116
Diagnostic instructions to monitor the hardware ........................................................................117
Reading the states of the LEDs on the CPU .............................................................................117
Instructions for reading the diagnostic status of the devices .....................................................117

6.6
6.6.1
6.6.2

High-speed counter (HSC) .........................................................................................................118
Operation of the high-speed counter .........................................................................................119
Configuration of the HSC ...........................................................................................................125

Easy to communicate between devices ............................................................................................... 127
7.1

Creating a network connection ..................................................................................................128

7.2

Communication options .............................................................................................................129

7.3

Number of asynchronous communication connections .............................................................131

7.4

PROFINET and PROFIBUS instructions ...................................................................................132

7.5
7.5.1
7.5.1.1
7.5.1.2
7.5.1.3
7.5.2

PROFINET .................................................................................................................................133
Open user communication .........................................................................................................133
Ad hoc mode ..............................................................................................................................134
Connection IDs for the Open user communication instructions .................................................134
Parameters for the PROFINET connection ...............................................................................137
Configuring the Local/Partner connection path..........................................................................140

7.6
7.6.1
7.6.2
7.6.3
7.6.4

PROFIBUS .................................................................................................................................142
Communications services of the PROFIBUS CMs ....................................................................144
Reference to the PROFIBUS CM user manuals ........................................................................145
Adding the CM 1243-5 (DP master) module and a DP slave ....................................................145
Assigning PROFIBUS addresses to the CM 1243-5 module and DP slave ..............................146

7.7
7.7.1
7.7.2

AS-i ............................................................................................................................................148
Adding the AS-i master CM 1243-2 and AS-i slave ...................................................................149
Assigning an AS-i address to an AS-i slave ..............................................................................150

7.8
7.8.1
7.8.2
7.8.3

S7 communication .....................................................................................................................153
GET and PUT instructions .........................................................................................................153
Creating an S7 connection .........................................................................................................154
GET/PUT connection parameter assignment ............................................................................155

7.9
7.9.1

GPRS .........................................................................................................................................156
Connection to a GSM network ...................................................................................................156

7.10
7.10.1
7.10.2
7.10.3
7.10.4

PtP, USS, and Modbus communication protocols .....................................................................163
Point-to-point communication ....................................................................................................163
Using the serial communication interfaces ................................................................................163
PtP instructions ..........................................................................................................................164
USS instructions.........................................................................................................................165

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7.10.5
8

Modbus instructions .................................................................................................................. 167

PID is easy ..........................................................................................................................................169
8.1

Inserting the PID instruction and technology object .................................................................. 171

8.2

PID_Compact instruction........................................................................................................... 173

8.3

PID_Compact instruction ErrorBit parameters .......................................................................... 177

8.4

PID_3Step instruction ................................................................................................................ 179

8.5

PID_3Step instruction ErrorBit parameters ............................................................................... 186

8.6

Configuring the PID controller ................................................................................................... 188

8.7

Commissioning the PID controller ............................................................................................. 190

Web server for easy Internet connectivity .............................................................................................193
9.1

Easy to use the standard Web pages ....................................................................................... 194

9.2
9.2.1
9.2.2

Constraints that can affect the use of the Web server .............................................................. 196
Feature restrictions when the Internet options disable JavaScript ........................................... 197
Feature restrictions when the Internet options do not allow cookies ........................................ 198

9.3
9.3.1
9.3.2
9.3.3
9.3.4

Easy to create user-defined web pages .................................................................................... 198
Easy to create custom "user-defined" web pages .................................................................... 198
Constraints specific to user-defined Web pages....................................................................... 199
Configuration of a user-defined Web page ............................................................................... 200
Using the WWW instruction ...................................................................................................... 201

Motion control is easy ..........................................................................................................................203
10.1

Phasing ..................................................................................................................................... 208

10.2

Configuring a pulse generator ................................................................................................... 210

10.3

Configuring the axis .................................................................................................................. 211

10.4

Configuring the TO_CommandTable_PTO ............................................................................... 214

10.5
10.5.1
10.5.2
10.5.3
10.5.4
10.5.5
10.5.6
10.5.7
10.5.8
10.5.9
10.5.10
10.5.11
10.5.12
10.5.13

Motion control instructions ........................................................................................................ 217
MC instruction overview ............................................................................................................ 217
MC_Power (Release/block axis) instruction.............................................................................. 217
MC_Reset (Confirm error) instruction ....................................................................................... 221
MC_Home (Home axis) instruction ........................................................................................... 222
MC_Halt (Pause axis) instruction .............................................................................................. 224
MC_MoveAbsolute (Position axis absolutely) instruction ......................................................... 226
MC_MoveRelative (Position axis relatively) instruction ............................................................ 228
MC_MoveVelocity (Move axis at predefined velocity) instruction ............................................. 230
MC_MoveJog (Move axis in jog mode) instruction ................................................................... 233
MC_CommandTable (Run axis commans as movement sequence) instruction ...................... 235
MC_ChangeDynamic (Change dynamc settings for the axis) instruction ................................. 237
MC_WriteParam (write parameters of a technology object) instruction .................................... 239
MC_ReadParam instruction (read parameters of a technology object) instruction .................. 241

10.6
10.6.1
10.6.2
10.6.3
10.6.3.1

Operation of motion control for S7-1200 ................................................................................... 242
CPU outputs used for motion control ........................................................................................ 242
Hardware and software limit switches for motion control .......................................................... 244
Homing ...................................................................................................................................... 247
Homing the axis ........................................................................................................................ 247
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10.6.3.2 Configuration of homing parameters .........................................................................................249
10.6.3.3 Sequence for active homing ......................................................................................................251
10.7
11

Commissioning...........................................................................................................................252

Easy to use the online tools................................................................................................................. 257
11.1

Going online and connecting to a CPU ......................................................................................257

11.2

Interacting with the online CPU..................................................................................................258

11.3

Going online to monitor the values in the CPU ..........................................................................259

11.4

Displaying status of the user program is easy ...........................................................................260

11.5

Using a watch table for monitoring the CPU ..............................................................................260

11.6

Using the force table ..................................................................................................................261

11.7

Capturing the online values of a DB to reset the start values ....................................................264

11.8

Copying elements of the project ................................................................................................265

11.9

Comparing offline and online CPUs ...........................................................................................266

11.10

Displaying the diagnostic events................................................................................................267

11.11

Setting the IP address and time of day ......................................................................................267

11.12

Resetting to factory settings.......................................................................................................268

11.13

Updating firmware ......................................................................................................................269

11.14

Downloading an IP address to an online CPU ...........................................................................270

11.15

Using the "unspecified CPU" to upload the hardware configuration ..........................................271

11.16
Downloading in RUN mode ........................................................................................................272
11.16.1 Changing your program in RUN mode ......................................................................................273
11.17
12

Tracing and recording CPU data on trigger conditions ..............................................................274

IO-Link is easy .................................................................................................................................... 275
12.1

Overview of IO-Link technology .................................................................................................275

12.2

Components of an IO-Link system.............................................................................................275

12.3

After power-up............................................................................................................................275

12.4

IO-Link protocol ..........................................................................................................................276

12.5

Configuration in the fieldbus ......................................................................................................276

12.6

IO-Link and your STEP 7 program.............................................................................................276

12.7

The SM 1278 4xIO-Link Master .................................................................................................277

Technical specifications ...................................................................................................................... 281
A.1

General technical specifications ................................................................................................281

A.2

CPU modules .............................................................................................................................289

A.3
A.3.1
A.3.2
A.3.3

Digital I/O modules .....................................................................................................................293
SB 1221, SB 1222, and SB 1223 digital input/output (DI, DQ, and DI/DQ)...............................293
SM 1221 digital input (DI) ..........................................................................................................296
SM 1222 digital output (DQ) ......................................................................................................297

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A.3.4
A.3.5

SM 1223 VDC digital input/output (DI / DQ) ............................................................................. 299
SM 1223 120/230 VAC input / Relay output ............................................................................. 300

A.4
A.4.1
A.4.2
A.4.3

Specifications for the digital inputs and outputs ........................................................................ 302
24 VDC digital inputs (DI).......................................................................................................... 302
120/230 VAC digital AC inputs .................................................................................................. 303
Digital outputs (DQ) ................................................................................................................... 304

A.5
A.5.1
A.5.2
A.5.3
A.5.4
A.5.5

Analog I/O modules ................................................................................................................... 306
SB 1231 and SB 1232 analog input (AI) and output (AQ) ........................................................ 306
SM 1231 analog input (AI) ........................................................................................................ 307
SM 1232 analog output (AQ) .................................................................................................... 308
SM 1234 analog input/output (AI/AQ) ....................................................................................... 308
Wiring diagrams for SM 1231 (AI), SM 1232 (AQ), and SM 1234 (AI/AQ) ............................... 309

A.6

BB 1297 battery board .............................................................................................................. 310

A.7
A.7.1
A.7.2
A.7.3
A.7.4
A.7.5
A.7.6

Specifications for the analog I/O ............................................................................................... 311
Specifications for the analog inputs (CPU, SM, and SB) .......................................................... 311
Input (AI) measurement ranges for voltage and current ........................................................... 312
Step response for the analog inputs (AI) .................................................................................. 313
Sample time and update times for the analog inputs ................................................................ 314
Specifications for the analog outputs ........................................................................................ 315
Output (AQ) measurement ranges for voltage and current ...................................................... 315

A.8
A.8.1
A.8.2
A.8.3
A.8.4
A.8.5
A.8.6
A.8.7
A.8.8

RTD and Thermocouple modules ............................................................................................. 317
SB 1231 RTD and SB 1231 TC specifications.......................................................................... 318
SM 1231 RTD specifications ..................................................................................................... 319
SM 1231 TC specifications ....................................................................................................... 321
Analog input specifications for RTD and TC (SM and SB) ....................................................... 323
Thermocouple type ................................................................................................................... 324
Thermocouple filter selection and update times ....................................................................... 325
RTD sensor type selection table ............................................................................................... 326
RTD filter selection and update times ....................................................................................... 327

A.9
A.9.1
A.9.1.1
A.9.1.2
A.9.2
A.9.2.1
A.9.3
A.9.4
A.9.4.1
A.9.4.2
A.9.4.3

Communication interfaces......................................................................................................... 328
PROFIBUS master/slave .......................................................................................................... 328
CM 1242-5 PROFIBUS slave.................................................................................................... 328
CM 1243-5 PROFIBUS master ................................................................................................. 329
GPRS CP .................................................................................................................................. 331
Technical specifications of the CP 1242-7 GPRS .................................................................... 331
Teleservice (TS) ........................................................................................................................ 334
RS485, RS232 and RS422 communication .............................................................................. 334
CB 1241 RS485 specifications.................................................................................................. 334
CM 1241 RS422/485 specifications .......................................................................................... 337
CM 1241 RS232 specifications ................................................................................................. 338

A.10
A.10.1
A.10.1.1
A.10.1.2

Technology modules ................................................................................................................. 339
SM 1278 4xIO-Link Master SM ................................................................................................. 339
SM 1278 4xIO-Link Master signal module specifications ......................................................... 339
SM 1278 4xIO-Link Master SM wiring diagrams....................................................................... 342

A.11
A.11.1
A.11.2
A.11.3

Companion products ................................................................................................................. 343
PM 1207 power module ............................................................................................................ 343
CSM 1277 compact switch module ........................................................................................... 343
CM CANopen module ............................................................................................................... 344

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Exchanging a V3.0 CPU for a V4.0 CPU ............................................................................................. 345
B.1

Exchanging a V3.0 CPU for a V4.0 CPU ...................................................................................345

Index................................................................................................................................................... 349

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Table of contents

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Introducing the powerful and flexible S7-1200
1.1

Introducing the S7-1200 PLC
The S7-1200 controller provides the flexibility and power to control a wide variety of devices
in support of your automation needs. The compact design, flexible configuration, and
powerful instruction set combine to make the S7-1200 a perfect solution for controlling a
wide variety of applications.
The CPU combines a microprocessor, an integrated power supply, input and output circuits,
built-in PROFINET, high-speed motion control I/O, and on-board analog inputs in a compact
housing to create a powerful controller. After you download your program, the CPU contains
the logic required to monitor and control the devices in your application. The CPU monitors
the inputs and changes the outputs according to the logic of your user program, which can
include Boolean logic, counting, timing, complex math operations, and communications with
other intelligent devices.
The CPU provides a PROFINET port for communication over a PROFINET network.
Additional modules are available for communicating over PROFIBUS, GPRS, RS485 or
RS232 networks.

① Power connector
② Memory card slot under top
door

③ Removable user wiring
connectors (behind the
doors)

④ Status LEDs for the onboard I/O

⑤ PROFINET connector (on
the bottom of the CPU)

Several security features help protect access to both the CPU and the control program:
● Every CPU provides password protection (Page 82) that allows you to configure access
to the CPU functions.
● You can use "know-how protection" (Page 84) to hide the code within a specific block.
● You can use copy protection (Page 85) to bind your program to a specific memory card or
CPU.

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1.1 Introducing the S7-1200 PLC
Table 1- 1

Comparing the CPU models

Feature

CPU 1211C

CPU 1212C

CPU 1214C

CPU 1215C

CPU 1217C

Physical size (mm)

90 x 100 x 75

110 x 100 x 75

130 x 100 x 75

150 x 100 x 75

User memory

Work

30 Kbytes

50 Kbytes

75 Kbytes

100 Kbytes

125 Kbytes

Load

1 Mbyte

4 Mbytes

Retentive

10 Kbytes

Digital

6 inputs/4
outputs

8 inputs/6
outputs

14 inputs/10
outputs

Analog

2 inputs

2 inputs/2
outputs

Inputs (I)

1024 bytes

Outputs (Q)

Local on-board
I/O

Process image
size

1024 bytes

Bit memory (M)

4096 bytes

8192 bytes

Signal module (SM) expansion

None

Signal board (SB), Battery board
(BB), or communication board
(CB)

Communication module (CM)
(left-side expansion)

High-speed
counters

Total

Up to 6 configured to use any built-in or SB inputs

1 MHz

Ib.2 to Ib.5

Ia.0 to Ia.5

Ia.6 to Ia.7

Ia.6 to Ib.5

Ia.6 to Ib.1

100/180
30/120
Pulse

outputs2

kHz

Total

Up to 4 configured to use any built-in or SB outputs

1 MHz

Qa.0 to Qa.3

100 kHz

Qa.0 to Qa.3

Qa.4 to Qb.1

20 kHz

Qa.4 to Qa.5

Qa.4 to Qb.1

Memory card

SIMATIC Memory card (optional)

Real time clock retention time

20 days, typ./12 day min. at 40 degrees C (maintenance-free Super Capacitor)

PROFINET
Ethernet communication port

Real math execution speed

2.3 μs/instruction

Boolean execution speed

0.08 μs/instruction

The slower speed is applicable when the HSC is configured for quadrature mode of operation.

For CPU models with relay outputs, you must install a digital signal (SB) to use the pulse outputs.

The different CPU models provide a diversity of features and capabilities that help you create
effective solutions for your varied applications. For detailed information about a specific
CPU, see the technical specifications (Page 281).

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Introducing the powerful and flexible S7-1200
1.1 Introducing the S7-1200 PLC
Table 1- 2

Blocks, timers, and counters supported by S7-1200

Element
Blocks

Description
Type

OB, FB, FC, DB

Size

30 Kbytes (CPU 1211C)
50 Kbytes (CPU 1212C)
64 Kbytes (CPU 1214C, CPU 1215C, and CPU 1217C)

Quantity

Up to 1024 blocks total (OBs + FBs + FCs + DBs)

Nesting depth

16 from the program cycle or startup OB;
6 from any interrupt event OB

OBs

Timers

Counters

Monitoring

Status of 2 code blocks can be monitored simultaneously

Program cycle

Multiple

Startup

Multiple

Time-delay interrupts

4 (1 per event)

Cyclic interrupts

4 (1 per event)

Hardware interrupts

50 (1 per event)

Time error interrupts

Diagnostic error interrupts

Pull or plug of modules

Rack or station failure

Time of day

Multiple

Status

Update

Profile

Type

IEC

Quantity

Limited only by memory size

Storage

Structure in DB, 16 bytes per timer

Type

IEC

Quantity

Limited only by memory size

Storage

Structure in DB, size dependent upon count type
•

SInt, USInt: 3 bytes

•

Int, UInt: 6 bytes

•

DInt, UDInt: 12 bytes

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Introducing the powerful and flexible S7-1200
1.2 Expansion capability of the CPU

1.2

Expansion capability of the CPU
The S7-1200 family provides a variety of modules and plug-in boards for expanding the
capabilities of the CPU with additional I/O or other communication protocols. For detailed
information about a specific module, see the technical specifications (Page 281).

①
②
③
④
Table 1- 3

Communication module (CM or communication processor (CP)
CPU
Signal board (SB), communication board (CB), or Battery Board (BB)
Signal module (SM)

Digital signal modules and signal boards

Type

Input only

③ digital SB

•

4 x 24 VDC In,
200 kHz

•

4 x 24 VDC Out, 200 kH
z

•

4 x 5 VDC In,
200 kHz

•

4 x 5 VDC Out,
200 kHz

8 x 24 VDC In

•
•

④ digital SM

•

16 x 24 VDC In

Output only

Combination In/Out
•

2 x 24 VDC In/2 x 24 VDC Out

•

2 x 24 VDC In/2 x 24 VDC Out,
200 kHz

•

2 x 5 VDC In/2 x 5 VDC Out,
200 kHz

8 x 24 VDC Out

•

8 x 24 VDC In/8 x 24 VDC Out

8 x Relay Out

•

8 x 24 VDC In/8 x Relay Out

•

8 x Relay Out
(Changeover)

•

8 x 120/230 VAC In/8 x Relay Out

•

16 x 24 VDC Out

•

16 x 24 VDC In/16 x 24 VDC Out

•

16 x Relay Out

•

16 x 24 VDC In/16 x Relay Out

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Introducing the powerful and flexible S7-1200
1.2 Expansion capability of the CPU
Table 1- 4

Analog signal modules and signal boards

Type

Input only

③ analog SB

•

1 x 12 bit Analog In

•

1 x 16 bit RTD

•

1 x 16 bit Thermocouple

•

④ analog SM

Combination In/Out

•

1 x Analog Out

4 x Analog In

•

2 x Analog Out

•

4 x Analog In x 16 bit

•

4 x Analog Out

•

8 x Analog In

•

Thermocouple:

•

Table 1- 5

Output only

–

4 x 16 bit TC

–

8 x 16 bit TC

4 x Analog In/2 x Analog Out

RTD:
–

4 x 16 bit RTD

–

8 x 16 bit RTD

Communication interfaces

Module

Type

Description

① Communication module (CM)

RS232

Full-duplex

RS422/485

Full-duplex (RS422)
Half-duplex (RS485)

PROFIBUS Master

DPV1

PROFIBUS Slave

DPV1

AS-i Master (CM 1243-2)

AS-Interface

① Communication processor (CP)

Modem connectivity

GPRS

③ Communication board (CB)

RS485

Half-duplex

TeleService1

TS Adapter IE Basic

Connection to CPU

TS Adapter GSM

GSM/GPRS

TS Adapter Modem

Modem

TS Adapter ISDN

ISDN

TS Adapter RS232

RS232

The TS Adapter IE Basic allows you to connect various communication interfaces to the PROFINET port of the CPU
using an Ethernet cable. You can install up to 3 TS adapter modules onto the TS Adapter IE Basic.

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Introducing the powerful and flexible S7-1200
1.2 Expansion capability of the CPU
Table 1- 6

Technology modules

Module

Type

Description

④ IO Link

SM 1278 4xIO-Link Master

Supports 4 IO link slaves

Table 1- 7

Other boards

Module

Description

③ Battery board

Plugs into expansion board interface on front of CPU. Provides long term
backup of realtime clock

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Introducing the powerful and flexible S7-1200
1.3 S7-1200 modules

1.3
Table 1- 8

S7-1200 modules
S7-1200 expansion modules

Type of module
The CPU supports one plug-in
expansion board:
•

A signal board (SB) provides
additional I/O for your CPU.
The SB connects on the front of
the CPU.

•

A communication board (CB)
allows you to add another
communication port to your
CPU.

•

A battery board (BB) allows you
to provide long term backup of
the realtime clock.

Signal modules (SMs) add
additional functionality to the CPU.
SMs connect to the right side of the
CPU.
•

Digital I/O

•

Analog I/O

•

RTD and thermocouple

•

SM 1278 IO-Link Master

Communication modules (CMs)
and communications processors
(CPs) add communication options
to the CPU, such as for
PROFIBUS or RS232/RS485
connectivity (for PtP, Modbus or
USS), or the AS-i master. A CP
provides capabilities for other types
of communication, such as to
connect the CPU over a GPRS
network.
•

The CPU supports up to 3 CMs
or CPs

•

Each CM or CP connects to the
left side of the CPU (or to the
left side of another CM or CP)

Description

①

Status LEDs on
the SB

②

Removable user
wiring connector

①

Status LEDs

②

Bus connector
slide tab

③

Removable user
wiring connector

①

Status LEDs

②

Communication
connector

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Introducing the powerful and flexible S7-1200
1.4 Basic HMI panels

1.4

Basic HMI panels
The SIMATIC HMI Basic Panels provide touch-screen devices for basic operator control and
monitoring tasks. All panels have a protection rating for IP65 and have CE, UL, cULus, and
NEMA 4x certification.

Basic HMI Panel

KP 300 Basic PN

Description

Technical data

3.6" membrane keyboard with 10 freely
configurable tactile keys

•

250 tags

•

50 process screens

•

200 alarms

•

Mono (STN, black/white)

•

87 mm x 31 mm (3.6")

•

Backlight color programmed (white,
green, yellow, or red)

•

Resolution: 240 x 80

4" touch screen with 4 tactile keys

KTP 400 Basic PN

•

25 curves

•

40 KB recipe memory

•

5 recipes, 20 data records, 20 entries

•

250 tags

•

Mono (STN, gray scale)

•

50 process screens

•

76.79 mm x 57.59 mm (3.8")
Portrait or landscape

•

200 alarms

Resolution: 320 x 240

•

25 curves

6" touch screen with 6 tactile keys
•

Color (TFT, 256 colors) or Mono
(STN, gray scales)

•

115.2 mm x 86.4 mm (5.7")
Portrait or landscape

•

Resolution: 320 x 240

KTP 600 Basic PN
10" touch screen with 8 tactile keys

•

40 KB recipe memory

•

5 recipes, 20 data records, 20 entries

•

500 tags

•

50 process screens

•

200 alarms

•

25 curves

•

40 KB recipe memory

•

5 recipes, 20 data records, 20 entries

•

500 tags

•

Color (TFT, 256 colors)

•

50 process screens

•

211.2 mm x 158.4 mm (10.4")

•

200 alarms

•

Resolution: 640 x 480

•

25 curves

•

40 KB recipe memory

•

5 recipes, 20 data records, 20 entries

KTP 1000 Basic PN
15" touch screen

•

500 tags

•

Color (TFT, 256 colors)

•

50 process screens

•

304.1 mm x 228.1 mm (15.1")

•

200 alarms

•

Resolution: 1024 x 768

•

25 curves

•

40 KB recipe memory (integrated
flash)

•

5 recipes, 20 data records, 20 entries

TP 1500 Basic PN

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Introducing the powerful and flexible S7-1200
1.5 Mounting dimensions and clearance requirements

1.5

Mounting dimensions and clearance requirements
The S7-1200 PLC is designed to be easy to install. Whether mounted on a panel or on a
standard DIN rail, the compact size makes efficient use of space.
Refer to the S7-1200 System Manual for specific requirements and guidelines for installation.

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Introducing the powerful and flexible S7-1200
1.5 Mounting dimensions and clearance requirements
Table 1- 9

Mounting dimensions (mm)

S7-1200 Devices
CPU

Signal modules

Width A (mm)

Width B (mm)

Width C (mm)

CPU 1211C and CPU 1212C

CPU 1214C

110

CPU 1215C

130

65 (top)

Bottom:
C1: 32.5
C2: 65
C3: 32.5

CPU 1217C

150

Bottom:
C1: 37.5
C2: 75
C3: 37.5

Digital 8 and 16 point

22.5

Digital DQ 8 x Relay (Changeover)

Analog 16 point

TS Adapter

TS Module

Analog 2, 4, and 8 point
Thermocouple 4 and 8 point
RTD 4 point
SM 1278 IO Link-Master

RTD 8 point
Communication
interfaces

CM 1241 RS232, and
CM 1241 RS422/485
CM 1243-5 PROFIBUS master and
CM 1242-5 PROFIBUS slave
CM 1242-2 AS-i Master
CP 1242-7 GPRS
TS (Teleservice) Adapter IE Basic1

Before installing the TS (Teleservice) Adapter IE Basic, you must first connect the TS Adapter and a TS module. The
total width ("width A") is 60 mm.

Each CPU, SM, CM, and CP supports mounting on either a DIN rail or on a panel. Use the
DIN rail clips on the module to secure the device on the rail. These clips also snap into an
extended position to provide screw mounting positions to mount the unit directly on a panel.
The interior dimension of the hole for the DIN clips on the device is 4.3 mm.
A 25 mm thermal zone must be provided above and below the unit for free air circulation.

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Introducing the powerful and flexible S7-1200
1.5 Mounting dimensions and clearance requirements
The S7-1200 equipment is designed to be easy to install. You can install an S7-1200 either
on a panel or on a standard rail, and you can orient the S7-1200 either horizontally or
vertically. The small size of the S7-1200 allows you to make efficient use of space.
WARNING
Installation requirements for S7-1200 PLCs
The SIMATIC S7-1200 PLCs are Open Type Controllers. It is required that you install the
S7-1200 in a housing, cabinet, or electric control room. Entry to the housing, cabinet, or
electric control room should be limited to authorized personnel.
Failure to follow these installation requirements could result in death, severe personal injury
and/or property damage.
Always follow these requirements when installing S7-1200 PLCs.

Separate the S7-1200 devices from heat, high voltage, and electrical noise
As a general rule for laying out the devices of your system, always separate the devices that
generate high voltage and high electrical noise from the low-voltage, logic-type devices such
as the S7-1200.
When configuring the layout of the S7-1200 inside your panel, consider the heat-generating
devices and locate the electronic-type devices in the cooler areas of your cabinet. Reducing
the exposure to a high-temperature environment will extend the operating life of any
electronic device.
Consider also the routing of the wiring for the devices in the panel. Avoid placing low-voltage
signal wires and communications cables in the same tray with AC power wiring and highenergy, rapidly-switched DC wiring.

Provide adequate clearance for cooling and wiring
S7-1200 devices are designed for natural convection cooling. For proper cooling, you must
provide a clearance of at least 25 mm above and below the devices. Also, allow at least 25
mm of depth between the front of the modules and the inside of the enclosure.
CAUTION
For vertical mounting, the maximum allowable ambient temperature is reduced by 10
degrees C.
Orient a vertically mounted S7-1200 system as shown in the following figure.
Ensure that the S7-1200 system is mounted correctly.
When planning your layout for the S7-1200 system, allow enough clearance for the wiring
and communications cable connections.

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Introducing the powerful and flexible S7-1200
1.5 Mounting dimensions and clearance requirements

①
②

Side view
Horizontal installation

③
④

Vertical installation
Clearance area

WARNING
Installation or removal of S7-1200 or related equipment with the power applied could cause
electric shock or unexpected operation of equipment.
Failure to disable all power to the S7-1200 and related equipment during installation or
removal procedures could result in death, severe personal injury and/or property damage
due to electric shock or unexpected equipment operation.
Always follow appropriate safety precautions and ensure that power to the S7-1200 is
disabled before attempting to install or remove S7-1200 CPUs or related equipment.
Always ensure that whenever you replace or install an S7-1200 device you use the correct
module or equivalent device.
WARNING
Correct installation of S7-1200 modules
Incorrect installation of an S7-1200 module can cause the program in the S7-1200 to
function unpredictably.
Failure to replace an S7-1200 device with the same model, orientation, or order could result
in death, severe personal injury and/or property damage due to unexpected equipment
operation.
Replace an S7-1200 device with the same model, and be sure to orient and position it
correctly.

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Introducing the powerful and flexible S7-1200
1.6 New features

1.6

New features
The following features are new in this release:
● The S7-1200 supports new Organization Blocks (OBs) (Page 89) with differences in
priority levels and interrupts.
● The Web server (Page 193) now supports the display of standard Web pages and userdefined Web pages from a mobile device as well as from a PC. The standard Web pages
are available in English, German, French, Spanish, Italian, and Simplified Chinese with
this release.
● The "Download in Run" (Page 272) feature now supports a maximum of twenty blocks
that you can download in RUN mode. You can also add tags and modify tags in existing
data blocks and function blocks and download the modified data blocks in RUN mode.
● The online and diagnostic tools of STEP 7 provide the means to perform a firmware
update (Page 269) of your CPU, signal modules, communication modules, and attached
signal or communication board.
● STEP 7 includes a trace and logic analyzer function (Page 274) that you can use with the
V4.0 S7-1200 CPUs. With this feature, you can configure specific data that you want to
trace and record when the CPU meets a trigger condition that you define. The CPU
stores the recorded data, and STEP 7 provides tools for retrieving and analyzing the
recorded data.
● New programming instructions:
– Set tag on signal edge: R_TRIG, F_TRIG
– Write local time: WR_LOC_T
– String maximum length: MAX_LEN
– Time of day interrupts: SET_TINTL, CAN_TINT, ACT_TINT, QRY_TINT
– Process recipes: RecipeExport, RecipeImport
– Address handling: LOG2GEO, RD_ADDR
– Motion control: MC_WriteParam, MC_ReadParam
– Enable / disable password: ENDIS_PW
● HSC improvements to allow any HSC instruction input or output to be assigned to any
built-in or SB digital input
● PTO/PWM improvements to allow any PTO/PWM instruction input or output to be
assigned to any built-in or SB digital output
● Enhanced library features, including versioning

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Introducing the powerful and flexible S7-1200
1.6 New features

New modules for the S7-1200
New modules expand the power of the S7-1200 CPU and provide the flexibility to meet your
automation needs:
● New CPU 1217C DC/DC/DC with high-speed differential points
● New and improved S7-1200 signal modules. The new signal modules (6ES7 2xx-xxx320XB0) replace existing signal modules (6ES7 2xx-xxx30-0XB0). The new modules
provide:
– 4-20 mA range added to analog input and output modules
– Wirebreak detection when using 4-20 mA added to analog input modules
– Connector keying to prevent errors when plugging in field wiring connectors added to
modules with relay outputs
– Spare parts compatibility: you can employ the revised module in place of existing
modules without any changes.
● New spare parts available for use with S7-1200 CPUs
● New CPU 1217C Input Simulator (6ES7 274-1XK30-0XA0)
● New SM 1278 4xIO-Link Master (6ES7 278-4BD32-0XB0) functions as both a signal
module and a communication module, and allows connection of up to 4 IO-Link slaves (3wire connection) or 4 standard actuators or standard encoders
● New S7-1200 Potentiometer module (6ES7 274-1XA30-0XA0)
● New CM CANopen for S7-1200 is a plug-in module that allows you to connect CANopen
devices to the S7-1200 PLC. It can be configured to be both master or slave.

Exchanging your V3.0 CPU for a V4.0 CPU
If you are replacing an S7-1200 V3.0 CPU with an S7-1200 V4.0 CPU, take note of the
documented differences in the versions.

See also
Basic HMI panels (Page 22)

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STEP 7 makes the work easy

STEP 7 provides a user-friendly environment to develop controller logic, configure HMI
visualization, and setup network communication. To help increase your productivity, STEP 7
provides two different views of the project: a task-oriented set of portals that are organized
on the functionality of the tools (Portal view), or a project-oriented view of the elements within
the project (Project view). Choose which view helps you work most efficiently. With a single
click, you can toggle between the Portal view and the Project view.
Portal view

① Portals for the different tasks
② Tasks for the selected portal
③ Selection panel for the selected
action

④ Changes to the Project view

Project view

① Menus and toolbar
② Project navigator
③ Work area
④ Task cards
⑤ Inspector window
⑥ Changes to the Portal view
⑦ Editor bar
With all of these components in one place, you have easy access to every aspect of your
project. For example, the inspector window shows the properties and information for the
object that you have selected in the work area. As you select different objects, the inspector
window displays the properties that you can configure. The inspector window includes tabs
that allow you to see diagnostic information and other messages.
By showing all of the editors that are open, the editor bar helps you work more quickly and
efficiently. To toggle between the open editors, simply click the different editor. You can also
arrange two editors to appear together, arranged either vertically or horizontally. This feature
allows you to drag and drop between editors.

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STEP 7 makes the work easy
2.1 Easy to insert instructions into your user program

2.1

Easy to insert instructions into your user program
STEP 7 provides task cards that contain the instructions for your
program. The instructions are grouped according to function.

To create your program, you drag instructions from the task card
onto a network.

2.2

Easy access to your favorite instructions from a toolbar
STEP 7 provides a "Favorites" toolbar to give you quick access to the instructions that you
frequently use. Simply click the icon for the instruction to insert it into your network!
(For the "Favorites" in the instruction tree, doubleclick the icon.)
You can easily customize the
"Favorites" by adding new
instructions.
Simply drag and drop an
instruction to the "Favorites".
The instruction is now just a click
away!

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STEP 7 makes the work easy
2.3 Easy to add inputs or outputs to LAD and FBD instructions

2.3

Easy to add inputs or outputs to LAD and FBD instructions
Some of the instructions allow you to create additional inputs or outputs.
● To add an input or output, click the "Create" icon or right-click on an input stub for one of
the existing IN or OUT parameters and select the "Insert input" command.
● To remove an input or output, right-click on the stub for one of the existing IN or OUT
parameters (when there are more than the original two inputs) and select the "Delete"
command.

2.4

Expandable instructions
Some of the more complex instructions are expandable, displaying only the key inputs and
outputs. To display all the inputs and outputs, click the arrow at the bottom of the instruction.

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STEP 7 makes the work easy
2.5 Easy to change the operating mode of the CPU

2.5

Easy to change the operating mode of the CPU
The CPU does not have a physical switch for changing the operating mode (STOP or RUN).
Use the "Start CPU" and "Stop CPU" toolbar buttons to change the operating
mode of the CPU.
When you configure the CPU in the device configuration, you configure the start-up behavior
in the properties of the CPU (Page 76).
The "Online and diagnostics" portal also provides an operator panel for changing the
operating mode of the online CPU. To use the CPU operator panel, you must be connected
online to the CPU. The "Online tools" task card displays an operator panel that shows the
operating mode of the online CPU. The operator panel also allows you to change the
operating mode of the online CPU.
Use the button on the operator panel to change the operating mode
(STOP or RUN). The operator panel also provides an MRES button for
resetting the memory.

The color of the RUN/STOP indicator shows the current operating mode of the CPU. Yellow
indicates STOP mode, and green indicates RUN mode.
Refer to Operating Modes of the CPU in the S7-1200 System Manual for configuring the
default operating mode on power up.

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STEP 7 makes the work easy
2.6 Easy to modify the appearance and configuration of STEP 7

2.6

Easy to modify the appearance and configuration of STEP 7
You can select a variety of settings,
such as the appearance of the
interface, language, or the folder for
saving your work.
Select the "Settings" command from
the "Options" menu to change these
settings.

2.7

Project and global libraries for easy access
The global and project libraries allow you to reuse the stored objects throughout a project or
across projects. For example, you can create block templates for use in different projects
and adapt them to the particular requirements of your automation task. You can store a
variety of objects in the libraries, such as FCs, FBs, DBs, device configuration, data types,
watch tables, process screens, and faceplates. You can also save the components of the
HMI devices in your project.
Each project has a project library for storing the objects to be
used more than once within the project. This project library is
part of the project. Opening or closing the project opens or
closes the project library, and saving the project saves any
changes in the project library.

You can create your own global library to store the objects you want to make available for
other projects to use. When you create a new global library, you save this library to a
location on your computer or network.

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STEP 7 makes the work easy
2.8 Easy to select a version of an instruction

2.8

Easy to select a version of an instruction
The development and release cycles for certain sets of instructions (such as Modbus, PID
and motion) have created multiple released versions for these instructions. To help ensure
compatibility and migration with older projects, STEP 7 allows you to choose which version
of instruction to insert into your user program.
Click the icon on the instruction tree task card to enable the
headers and columns of the instruction tree.
To change the version of the instruction, select the
appropriate version from the drop-down list.

2.9

Easy to drag and drop between editors
To help you perform tasks quickly and easily,
STEP 7 allows you to drag and drop elements
from one editor to another. For example, you
can drag an input from the CPU to the address
of an instruction in your user program.
You must zoom in at least 200% to select the
inputs or outputs of the CPU.
Notice that the tag names are displayed not
only in the PLC tag table, but also are
displayed on the CPU.

To display two editors at one time, use the
"Split editor" menu commands or buttons in
the toolbar.

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STEP 7 makes the work easy
2.10 Changing the call type for a DB
To toggle between the editors that have been opened, click the icons in the editor bar.

2.10

Changing the call type for a DB
STEP 7 allows you to easily create or change the
association of a DB for an instruction or an FB that is in
an FB.
• You can switch the association between different DBs.
• You can switch the association between a singleinstance DB and a multi-instance DB.
• You can create an instance DB (if an instance DB is
missing or not available).
You can access the "Change call type" command either
by right-clicking the instruction or FB in the program
editor or by selecting the "Block call" command from the
"Options" menu.

The "Call options" dialog allows
you to select a single-instance
or multi-instance DB. You can
also select specific DBs from a
drop-down list of available DBs.

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STEP 7 makes the work easy
2.11 Temporarily disconnecting devices from a network

2.11

Temporarily disconnecting devices from a network
You can disconnect individual network devices from the subnet. Because the configuration of
the device is not removed from the project, you can easily restore the connection to the
device.

Right-click the interface port of the network
device and select the "Disconnect from
subnet" command from the context menu.

STEP 7 reconfigures the network connections, but does not remove the disconnected device
from the project. While the network connection is deleted, the interface addresses are not
changed.

When you download the new network connections, the CPU must be set to STOP mode.
To reconnect the device, simply create a new network connection to the port of the device.

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STEP 7 makes the work easy
2.12 Easy to virtually "unplug" modules without losing the configuration

2.12

Easy to virtually "unplug" modules without losing the configuration
STEP 7 provides a storage area for
"unplugged" modules. You can drag a
module from the rack to save the
configuration of that module. These
unplugged modules are saved with your
project, allowing you to reinsert the
module in the future without having to
reconfigure the parameters.
One use of this feature is for temporary
maintenance. Consider a scenario where
you might be waiting for a replacement
module and plan to temporarily use a
different module as a short-term
replacement. You could drag the
configured module from the rack to the
"Unplugged modules" and then insert the
temporary module.

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STEP 7 makes the work easy
2.12 Easy to virtually "unplug" modules without losing the configuration

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Getting started
3.1

Create a project
Working with STEP 7 is easy! See how quickly you can get started with creating a project.
In the Start portal, click the
"Create new project" task.
Enter a project name and click
the "Create" button.

After creating the project, select the Devices &
Networks portal.
Click the "Add new device" task.

Select the CPU to add to the project:
1. In the "Add new device" dialog, click the
"SIMATIC PLC" button.
2. Select a CPU from the list.
3. To add the selected CPU to the project, click
the "Add" button.
Note that the "Open device view" option is
selected. Clicking "Add" with this option selected
opens the "Device configuration" of the Project
view.

The Device view displays the
CPU that you added.

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Getting started
3.2 Create tags for the I/O of the CPU

3.2

Create tags for the I/O of the CPU
"PLC tags" are the symbolic names for I/O and addresses. After you create a PLC tag,
STEP 7 stores the tag in a tag table. All of the editors in your project (such as the program
editor, the device editor, the visualization editor, and the watch table editor) can access the
tag table.
With the device editor open, open a tag table.
You can see the open editors displayed in the editor bar.

In the tool bar, click the "Split editor space horizontally" button.
STEP 7 displays both the tag table and the
device editor together.

Zoom the device configuration to over 200% so that the I/O points of the CPU are legible and
selectable. Drag the inputs and outputs from the CPU to the tag table:
1. Select I0.0 and drag it to the first row of the tag table.
2. Change the tag name from "I0.0" to "Start".
3. Drag I0.1 to the tag table and change the name to "Stop".
4. Drag Q0.0 (on the bottom of the CPU) to the tag table and change the name to
"Running".

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Getting started
3.3 Create a simple network in your user program

With the tags entered into the PLC tag table, the tags are available to your user program.

3.3

Create a simple network in your user program
Your program code consists of instructions that the CPU executes in sequence. For this
example, use ladder logic (LAD) to create the program code. The LAD program is a
sequence of networks that resemble the rungs of a ladder.
To open the program editor, follow these steps:
1. Expand the "Program blocks" folder in the Project tree to
display the "Main [OB1]" block.
2. Double-click the "Main [OB1]" block.
The program editor opens the program block (OB1).

Use the buttons on the "Favorites" to insert contacts and coils onto the network.

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Getting started
3.3 Create a simple network in your user program

1. Click the "Normally open contact"
button on the "Favorites" to add a
contact to the network.
2. For this example, add a second
contact.
3. Click the "Output coil" button to
insert a coil.

The "Favorites" also provides a button for creating a branch
1. Select the left rail to select the rail
for the branch.
2. Click the "Open branch" icon to
add a branch to the rail of the
network.
3. Insert another normally open
contact to the open branch.
4. Drag the double-headed arrow to a
connection point (the green square
on the rung) between the two
contacts on the first rung.

To save the project, click the "Save project" button in the toolbar. Notice that you do not have
to finish editing the rung before saving. You can now associate the tag names with these
instructions.

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Getting started
3.4 Use the PLC tags in the tag table for addressing the instructions

3.4

Use the PLC tags in the tag table for addressing the instructions
Using the tag table, you can quickly enter the PLC tags for the addresses of the contacts and
coils.
1. Double-click the default address
above the first normally
open contact.
2. Click the selector icon to the right
of the address to open the tags in
the tag table.
3. From the drop-down list, select
"Start" for the first contact.
4. For the second contact, repeat the
preceding steps and select the tag
"Stop".
5. For the coil and the latching
contact, select the tag "Running".

You can also drag the I/O addresses directly
from the CPU. Simply split the work area of the
Project view (Page 34).
You must zoom the CPU to over 200% in order
to select the I/O points.
You can drag the I/O on the CPU in the "Device
configuration" to the LAD instruction in the
program editor to create not only the address for
the instruction, but also to create an entry in the
PLC tag table.

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Getting started
3.5 Add a "box" instruction

3.5

Add a "box" instruction
The program editor features a generic "box" instruction. After inserting this box instruction,
you then select the type of instruction, such as an ADD instruction, from a drop-down list.
Click the generic "box" instruction in
the "Favorites" tool bar.

The generic "box" instruction supports
a variety of instructions. For this
example, create an ADD instruction:
1. Click the yellow corner of the box
instruction to display the dropdown list of instructions.
2. Scroll down the list and select the
ADD instruction.
3. Click the yellow corner by the "?" to
select the data type for the inputs
and output.

You can now enter the tags (or
memory addresses) for the values to
use with the ADD instruction.

You can also create additional inputs for certain instructions:
1. Click one of the inputs inside the box.
2. Right-click to display the context menu and select the "Insert
input" command.

The ADD instruction now uses three inputs.

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Getting started
3.6 Use the CALCULATE instruction for a complex mathematical equation

3.6

Use the CALCULATE instruction for a complex mathematical
equation
The Calculate instruction lets you create a math function that operates on multiple input
parameters to produce the result, according to the equation that you define.
In the Basic instruction tree, expand the Math functions folder.
Double-click the Calculate instruction to insert the instruction
into your user program.

The unconfigured Calculate
instruction provides two input
parameters and an output
parameter.
Click the "???" and select the data types for the input and output
parameters. (The input and output parameters must all be the same
data type.)
For this example, select the "Real" data type.

Click the "Edit equation" icon to enter the equation.

For this example, enter the following equation for scaling a raw analog value. (The "In" and
"Out" designations correspond to the parameters of the Calculate instruction.)
Out value = ((Out high - Out low) / (In high - In low)) * (In value - In low) + Out low
Out

= ((in4 - in5) / (in2 - in3)) * (in1 - in3) + in5

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Getting started
3.6 Use the CALCULATE instruction for a complex mathematical equation
Where:

Out value

(Out)

Scaled output value

In value

(in1)

Analog input value

In high

(in2)

Upper limit for the scaled input value

In low

(in3)

Lower limit for the scaled input value

Out high

(in4)

Upper limit for the scaled output value

Out low

(in5)

Lower limit for the scaled output value

In the "Edit Calculate" box, enter the equation with the parameter names:
OUT = ((in4 - in5) / (in2 - in3)) * (in1 - in3) + in5

When you click "OK", the Calculate
instruction creates the inputs
required for the instruction.

Enter the tag names for the values
that correspond to the parameters.

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Getting started
3.7 Add an HMI device to the project

3.7

Add an HMI device to the project
Adding an HMI device to your project is
easy!

1. Double-click the "Add new device" icon.
2. Click the "SIMATIC HMI" button in the
Add new device" dialog.
3. Select the specific HMI device from the
list.
You can choose to run the HMI wizard
to help you configure the screens for
the HMI device.
4. Click "OK" to add the HMI device to
your project.

The TIA Portal adds the HMI device to the project.
The TIA Portal provides an HMI wizard that helps you
configure all of the screens and structure for your HMI
device.

If you do not run the HMI wizard, the TIA Portal creates a simple default HMI screen. You
can add additional screens or objects on screens later.

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Getting started
3.8 Create a network connection between the CPU and HMI device

3.8

Create a network connection between the CPU and HMI device
Creating a network is easy!
• Go to "Devices and Networks" and select the
Network view to display the CPU and HMI
device.
• To create a PROFINET network, drag a line
from the green box (Ethernet port) on one
device to the green box on the other device.
A network connection is created for the two
devices.

3.9

Create an HMI connection to share tags
By creating an HMI connection between the
two devices, you can easily share the tags
between the two devices.
• With the network connection selected, click
the "Connections" button and select "HMI
connection" from the drop-down list.
• The HMI connection turns the two devices
blue.
• Select the CPU device and drag the line to
the HMI device.
• The HMI connection allows you to configure
the HMI tags by selecting a list of PLC tags.

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Getting started
3.10 Create an HMI screen
You can use other options for creating an HMI connection:
● Dragging a PLC tag from the PLC tag table, the program editor or the device
configuration editor to the HMI screen editor automatically creates an HMI connection.
● Using the HMI wizard to browse for the PLC automatically creates the HMI connection.

3.10

Create an HMI screen
Even if you do not utilize the HMI wizard, configuring an HMI screen is easy.
STEP 7 provides a standard set of
libraries for inserting basic shapes,
interactive elements, and even standard
graphics.

To add an element, simply drag and drop one of the elements onto the screen. Use the
properties for the element (in the Inspector window) to configure the appearance and
behavior of the element.

You can also create elements on your screen by dragging and dropping PLC tags either
from the Project tree or the program editor to the HMI screen. The PLC tag becomes an
element on the screen. You can then use the properties to change the parameters for this
element.

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Getting started
3.11 Select a PLC tag for the HMI element

3.11

Select a PLC tag for the HMI element
After you create the element on your screen, use the properties of the element to assign a
PLC tag to the element. Click the selector button by the tag field to display the PLC tags of
the CPU.

You can also drag and drop PLC tags from the Project tree to the HMI screen. Display the
PLC tags in the "Details" view of the project tree and then drag the tag to the HMI screen.

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PLC concepts made easy
4.1

Tasks performed every scan cycle
Each scan cycle includes writing the outputs, reading the inputs, executing the user program
instructions, and performing system maintenance or background processing.
The cycle is referred to as a scan cycle or scan. Under
default conditions, all digital and analog I/O points are
updated synchronously with the scan cycle using an
internal memory area called the process image. The
process image contains a snapshot of the physical inputs
and outputs on the CPU, signal board, and signal
modules.

● The CPU reads the physical inputs just prior to the execution of the user program and
stores the input values in the process image input area. This ensures that these values
remain consistent throughout the execution of the user instructions.
● The CPU executes the logic of the user instructions and updates the output values in the
process image output area instead of writing to the actual physical outputs.
● After executing the user program, the CPU writes the resulting outputs from the process
image output area to the physical outputs.
This process provides consistent logic through the execution of the user instructions for a
given cycle and prevents the flickering of physical output points that might change state
multiple times in the process image output area.

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4.2 Operating modes of the CPU

STARTUP
A

Clears the input (or "I") memory

Initializes the outputs with either the last
value or the substitute value

Executes the startup OBs

Copies the state of the physical inputs to I
memory

Stores any interrupt events into the queue to
be processed in RUN mode

Enables the writing of the output (or "Q")
memory to the physical outputs

RUN

①
②

Writes Q memory to the physical outputs

③
④

Executes the program cycle OBs

⑤

Copies the state of the physical inputs to I
memory
Performs self-test diagnostics
Processes interrupts and communications
during any part of the scan cycle

You can change the default behavior for a module by removing it from this automatic update
of I/O. You can also immediately read and write digital and analog I/O values to the modules
when an instruction executes. Immediate reads of physical inputs do not update the process
image input area. Immediate writes to physical outputs update both the process image
output area and the physical output point.

4.2

Operating modes of the CPU
The CPU has three modes of operation: STOP mode, STARTUP mode, and RUN mode.
Status LEDs on the front of the CPU indicate the current mode of operation.
● In STOP mode, the CPU is not executing the program, and you can download a project.
The RUN/STOP LED is solid yellow.
● In STARTUP mode, the CPU executes any startup logic (if present). The CPU does not
process interrupt events during the startup mode. The RUN/STOP LED alternates
flashing between green and yellow.
● In RUN mode, the scan cycle executes repeatedly. Interrupt events can occur and the
CPU can process them at any point within the program cycle phase. You can download
some parts of a project in RUN mode. The RUN/STOP LED is solid green.
The CPU supports the warm restart method for entering the RUN mode. Warm restart does
not include a memory reset, but you can command a memory reset from STEP 7. A memory
reset clears all work memory, clears retentive and non-retentive memory areas, copies load
memory to work memory, and sets outputs to the configured "Reaction to CPU STOP". A
memory reset does not clear the diagnostics buffer or the permanently saved IP address. A
warm restart initializes all non-retentive system and user data.

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4.3 Execution of the user program
You can configure the "startup after POWER ON" setting of the CPU complete with restart
method using STEP 7. This configuration item appears under the Device Configuration for
the CPU under Startup. At power up, the CPU performs a sequence of power-up diagnostic
checks and system initialization. During system initialization, the CPU deletes all nonretentive bit memory and resets all non-retentive DB contents to initial values. The CPU then
enters the appropriate power-up mode. Certain errors will prevent the CPU from entering the
RUN mode. The CPU supports the following power-up modes: STOP mode, "Go to RUN
mode after warm restart", and "Go to previous mode after warm restart".
NOTICE
Warm restart mode configuration
The CPU can enter STOP mode due to repairable faults, such as failure of a replaceable
signal module, or temporary faults, such as power line disturbance or erratic power up
event.
If the CPU has been configured to "Warm restart mode prior to POWER OFF", it will not
return to RUN mode when the fault is repaired or removed until it receives a new command
from STEP 7 to go to RUN. Without a new command, the STOP mode is retained as the
mode prior to POWER OFF.
CPUs that are intended to operate independently of a STEP 7 connection should typically
be configured to "Warm restart - RUN" so that the CPU can be returned to RUN mode by a
power cycle following the removal of fault conditions.

The CPU does not provide a physical switch for changing the
operating mode. To change the operating mode of the CPU, STEP 7
provides the following tools:
• "Stop" and "Run" buttons on the STEP 7 toolbar
• CPU operator panel in the online tools
You can also include a STP instruction in your program to change the CPU to STOP mode.
This allows you to stop the execution of your program based on the program logic.

4.3

Execution of the user program
The CPU supports the following types of code blocks that allow you to create an efficient
structure for your user program:
● Organization blocks (OBs) define the structure of the program. Some OBs have
predefined behavior and start events, but you can also create OBs with custom start
events (Page 55).
● Functions (FCs) and function blocks (FBs) contain the program code that corresponds to
specific tasks or combinations of parameters. Each FC or FB provides a set of input and
output parameters for sharing data with the calling block. An FB also uses an associated
data block (called an instance DB) to maintain state of values between execution that can
be used by other blocks in the program.
● Data blocks (DBs) store data that can be used by the program blocks.

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4.3 Execution of the user program
The size of the user program, data, and configuration is limited by the available load memory
and work memory in the CPU (Page 15). There is no specific limit to the number of each
individual OB, FC, FB and DB block. However, the total number of blocks is limited to 1024.

4.3.1

Processing the scan cycle in RUN mode
For each scan cycle, the CPU writes the outputs, reads the inputs, executes the user
program, updates communication modules, and responds to user interrupt events and
communication requests. Communication requests are handled periodically throughout the
scan.
These actions (except for user interrupt events) are serviced regularly and in sequential
order. User interrupt events that are enabled are serviced according to priority in the order in
which they occur. For interrupt events, the CPU reads the inputs, executes the OB, and then
writes the outputs, using the associated process image partition (PIP), if applicable.
The system guarantees that the scan cycle will be completed in a time period called the
maximum cycle time; otherwise a time error event is generated.
● Each scan cycle begins by retrieving the current values of the digital and analog outputs
from the process image and then writing them to the physical outputs of the CPU, SB,
and SM modules configured for automatic I/O update (default configuration). When a
physical output is accessed by an instruction, both the output process image and the
physical output itself are updated.
● The scan cycle continues by reading the current values of the digital and analog inputs
from the CPU, SB, and SMs configured for automatic I/O update (default configuration),
and then writing these values to the process image. When a physical input is accessed
by an instruction, the value of the physical input is accessed by the instruction, but the
input process image is not updated.
● After reading the inputs, the user program is executed from the first instruction through
the end instruction. This includes all the program cycle OBs plus all their associated FCs
and FBs. The program cycle OBs are executed in order according to the OB number with
the lowest OB number executing first.
Communications processing occurs periodically throughout the scan, possibly interrupting
user program execution.
Self-diagnostic checks include periodic checks of the system and the I/O module status
checks.
Interrupts can occur during any part of the scan cycle, and are event-driven. When an event
occurs, the CPU interrupts the scan cycle and calls the OB that was configured to process
that event. After the OB finishes processing the event, the CPU resumes execution of the
user program at the point of interruption.

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4.3 Execution of the user program

4.3.2

OBs help you structure your user program
OBs control the execution of the user program. Specific events in the CPU trigger the
execution of an organization block. OBs cannot call each other or be called from an FC or
FB. Only an event such as a diagnostic interrupt or a time interval, can start the execution of
an OB. The CPU handles OBs according to their respective priority classes, with higher
priority OBs executing before lower priority OBs. The lowest priority class is 1 (for the main
program cycle), and the highest priority class is 24.

4.3.3

Event execution priorities and queuing
The CPU processing is controlled by events. An event triggers an interrupt OB to be
executed. You can specify the interrupt OB for an event during the creation of the block,
during the device configuration, or with an ATTACH or DETACH instruction. Some events
happen on a regular basis like the program cycle or cyclic events. Other events happen only
a single time, like the startup event and time delay events. Some events happen when the
hardware triggers an event, such as an edge event on an input point or a high speed counter
event. Events like the diagnostic error and time error event only happen when an error
occurs. The event priorities and queues are used to determine the processing order for the
event interrupt OBs.
The CPU processes events in order of priority where 1 is the lowest priority and 26 is the
highest priority. Prior to V4.0 of the S7-1200 CPU, each type of OB belonged to a fixed
priority class (1 to 26). With V4.0, you can assign a priority class to each OB that you
configure. You configure the priority number in the attributes of the OB properties.

Interruptible and non-interruptible execution modes
OBs execute in priority order of the events that trigger them. With V4.0 of the S7-1200 CPU,
you can configure OB execution to be interruptible or non-interruptible. Note that program
cycle OBs are always interruptible, but you can configure all other OBs to be either
interruptible or non-interruptible.
If you set interruptible mode, then if an OB is executing and a higher priority event occurs
before the OB completes its execution, the running OB is interrupted to allow the higherpriority event OB to run. The higher-priority event runs, and at its completion, the OB that
was interrupted continues. When multiple events occur while an interruptible OB is
executing, the CPU processes those events in priority order.
If you do not set interruptible mode, then an OB runs to completion when triggered
regardless of any other events that trigger during the time that it is running.

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4.3 Execution of the user program
Consider the following two cases where interrupt events trigger a cyclic OB and a time delay
OB. In both cases, the time delay OB (OB201) has no process image partition assignment
and executes at priority 4. The cyclic OB (OB200) has a process image partition assignment
of PIP1 and executes at priority 2. The following illustrations show the difference in execution
between non-interruptible and interruptible execution modes:

Figure 4-1

Case 1: Non-interruptible OB execution

Figure 4-2

Case 2: Interruptible OB execution

Note
If you configure the OB execution mode to be non-interruptible, then a time error OB cannot
interrupt OBs other than program cycle OBs. Prior to V4.0 of the S7-1200 CPU, a time error
OB could interrupt any executing OB. With V4.0, you must configure OB execution to be
interruptible if you want a time error OB (or any other higher priority OB) to be able to
interrupt executing OBs that are not program cycle OBs.

Understanding event execution priorities and queuing
The number of pending (queued) events from a single source is limited, using a different
queue for each event type. Upon reaching the limit of pending events for a given event type,
the next event is lost. Refer to the topic about time error interrupt OBs for more information
regarding queue overflows.
Each CPU event has an associated priority. In general, the CPU services events in order of
priority (highest priority first). The CPU services events of the same priority on a "first-come,
first-served" basis.

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4.3 Execution of the user program
Table 4- 1

OB events

Event

Quantity allowed

Program cycle

1 program cycle event

Default OB priority
14

Multiple OBs allowed
Startup

1 startup event 1

Multiple OBs allowed
Time delay

Up to 4 time events

1 OB per event
Cyclic interrupt

Up to 4 events

1 OB per event
Hardware interrupt

Up to 50 hardware interrupt events2

1 OB per event, but you can use the same OB for multiple
events

Time error

1 event (only if configured)3

22 or 264

Diagnostic error

1 event (only if configured)

Pull or plug of modules

1 event

Rack or station failure

1 event

Time of day

Up to 2 events

Status

1 event

Update

1 event

Profile

1 event

The startup event and the program cycle event never occur at the same time because the startup event runs to
completion before the program cycle event starts.

You can have more than 50 hardware interrupt event OBs if you use the DETACH and ATTACH instructions.

You can configure the CPU to stay in RUN if the scan cycle exceeds the maximum scan cycle time or you can use the
RE_TRIGR instruction to reset the cycle time. However, the CPU goes to STOP mode the second time that one scan
cycle exceeds the maximum scan cycle time.

The priority for a new V4.0 CPU is 22. If you exchange a V3.0 CPU for a V4.0 CPU, the priority is 26, the priority that
was in effect for V3.0. In either case, the priority field is editable and you can set the priority to any value in the range 22
to 26.

Refer to the topic "Exchanging a V3.0 CPU for a V4.0 CPU" for more details.
In addition, the CPU recognizes other events that do not have associated OBs. The following
table describes these events and the corresponding CPU actions:

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4.4 Memory areas, addressing and data types
Table 4- 2

Additional events

Event

Description

CPU action

I/O access error

Direct I/O read/write error

The CPU logs the first occurrence in the diagnostic
buffer and stays in RUN mode.

Max cycle time error

CPU exceeds the configured cycle time
twice

The CPU logs the error in the diagnostic buffer and
transitions to STOP mode.

Peripheral access error I/O error during process image update

The CPU logs the first occurrence in the diagnostic
buffer and stays in RUN mode.

Programming error

If the block with the error provides error handling, it
updates the error structure; if not, the CPU logs the
error in the diagnostic buffer and stays in RUN
mode.

program execution error

Interrupt latency
The interrupt event latency (the time from notification of the CPU that an event has occurred
until the CPU begins execution of the first instruction in the OB that services the event) is
approximately 175 µsec, provided that a program cycle OB is the only event service routine
active at the time of the interrupt event.

See also
Going online to monitor the values in the CPU (Page 259)

4.4

Memory areas, addressing and data types
The CPU provides the following memory areas to store the user program, data, and
configuration:
● Load memory is non-volatile storage for the user program, data and configuration. When
a project is downloaded to the CPU, it is first stored in the Load memory area. This area
is located either in a memory card (if present) or in the CPU. This non-volatile memory
area is maintained through a power loss. You can increase the amount of load memory
available for data logs by installing a memory card.
● Work memory is volatile storage for some elements of the user project while executing
the user program. The CPU copies some elements of the project from load memory into
work memory. This volatile area is lost when power is removed, and is restored by the
CPU when power is restored.
● Retentive memory is non-volatile storage for a limited quantity of work memory values.
The retentive memory area is used to store the values of selected user memory locations
during power loss. When a power down or power loss occurs, the CPU restores these
retentive values upon power up.

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An optional SIMATIC memory card provides an alternative memory for
storing your user program or a means for transferring your program. If you
use the memory card, the CPU runs the program from the memory card
and not from the memory in the CPU.
Check that the memory card is not write-protected. Slide the protection
switch away from the "Lock" position.
Use the optional SIMATIC memory card as a program card, as a transfer card, for collecting
data log files, or to perform a firmware update.
● Use the transfer card to copy your project to multiple CPUs without using STEP 7. The
transfer card copies a stored project from the card to the memory of the CPU. You must
remove the transfer card after copying the program to the CPU.
● The program card takes the place of CPU memory; all of your CPU functions are
controlled by the program card. Inserting the program card erases all of the internal load
memory of the CPU (including the user program and any forced I/O). The CPU then
executes the user program from the program card.
● You can also use the program card for collecting data log files (Page 112). The program
card provides more memory than the internal memory of the CPU. The Web server
function (Page 193) of the CPU allows you to download the data log files to a computer.
● You can also use a memory card to perform a firmware update. Refer to the S7-1200
System Manual for instructions.
Note
The program card must remain in the CPU. If you remove the program card, the CPU goes
to STOP mode.

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4.4.1

Data types supported by the S7-1200
Data types are used to specify both the size of a data element as well as how the data are to
be interpreted. Each instruction parameter supports at least one data type, and some
parameters support multiple data types. Hold the cursor over the parameter field of an
instruction to see which data types are supported for a given parameter.

Table 4- 3

Data types supported by the S7-1200

Data types

Description

Bit and bit-sequence
data types

•

Bool is a Boolean or bit value.

•

Byte is an 8-bit byte value.

•

Word is a 16-bit value.

•

DWord is a 32-bit double-word value.

•

USInt (unsigned 8-bit integer) and SInt (signed 8-bit integer) are "short" integers (8 bits or 1
byte of memory) that can be signed or unsigned.

•

UInt (unsigned 16-bit integer) and Int (signed 16-bit integer) are integers (16 bits or 1 word of
memory) that can be signed or unsigned.

•

UDInt (unsigned 32-bit integer) and DInt (signed 32-bit integer) are double integers (32 bits or
1 double-word of memory) that can be signed or unsigned.

Real number data
types

•

Real is a 32-bit Real number or floating-point value.

•

LReal is a 64-bit Real number or floating-point value.

Date and time data
types

•

Date is a 16-bit date value (similar to a UInt) that contains the number of days since January
1, 1990. The maximum date value is 65378 (16#FF62), which corresponds to December 31,
2168. All possible Date values are valid.

•

DTL (date and time long) is a structure of 12 bytes that saves information on date and time in
a predefined structure.

Integer data types

Character and string
data types

–

Year (UInt): 1970 to 2554

–

Month (USInt): 1 to 12

–

Day (USInt): 1 to 31

–

Weekday (USInt): 1 (Sunday) to 7 (Saturday)

–

Hours (USInt): 0 to 23

–

Minutes (USInt): 0 to 59

–

Seconds (USInt): 0 to 59

–

Nanoseconds (UDInt): 0 to 999999999

•

Time is a 32-bit IEC time value (similar to a Dint) that stores the number of milliseconds (from
0 to 24 days 20 hours 31 minutes 23 seconds and 647 ms). All possible Time values are
valid. Time values can be used for calculations, and negative times are possible.

•

TOD (time of day) is a 32-bit time-of-day value (similar to a Dint) that contains the number of
milliseconds since midnight (from 0 to 86399999).

•

Char is an 8-bit single character.

•

String is a variable-length string of up to 254 characters.

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Data types

Description

Array and structure
data types

•

Array contains multiple elements of the same data type. Arrays can be created in the block
interface editors for OB, FC, FB, and DB. You cannot create an array in the PLC tags editor.

Struct defines a structure of data consisting of other data types. The Struct data type can be
used to handle a group of related process data as a single data unit. You declare the name
and internal data structure for the Struct data type in the data block editor or a block interface
editor.
Arrays and structures can also be assembled into a larger structure. A structure can be nested
up to eight levels deep. For example, you can create a structure of structures that contain arrays.
•

PLC data types

PLC Data type is a user-defined data structure that defines a custom data structure that you can
use multiple times in your program. When you create a PLC Data type, the new PLC Data type
appears in the data type selector drop drop-lists in the DB editor and code block interface editor.
PLC Data types can be used directly as a data type in a code block interface or in data blocks.
PLC Data types can be used as a template for the creation of multiple global data blocks that use
the same data structure.

Pointer data types

•

Pointer provides an indirect reference to the address of a tag. It occupies 6 bytes (48 bits) in
memory and can include the following information to a variable: DB number (or 0 if the data is
not stored in a DB), memory area in the CPU, and the memory address.

•

Any provides an indirect reference to the beginning of a data area and identifies its length.
The Any pointer uses 10 bytes in memory and can include the following information: Data
type of the data elements, number of data elements, memory area or DB number, and the
"Byte.Bit" starting address of the data.

•

Variant provides an indirect reference to tags of different data types or parameters. The
Variant pointer recognizes structures and individual structural components. The Variant does
not occupy any space in memory.

Although not available as data types, the following BCD (binary coded decimal) numeric
formats are supported by the conversion instructions.
● BCD16 is a 16-bit value (-999 to 999).
● BCD32 is a 32-bit value (-9999999 to 9999999).

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4.4.2

Addressing memory areas
STEP 7 facilitates symbolic programming. You create symbolic names or "tags" for the
addresses of the data, whether as PLC tags relating to memory addresses and I/O points or
as local variables used within a code block. To use these tags in your user program, simply
enter the tag name for the instruction parameter. For a better understanding of how the CPU
structures and addresses the memory areas, the following paragraphs explain the "absolute"
addressing that is referenced by the PLC tags. The CPU provides several options for storing
data during the execution of the user program:
● Global memory: The CPU provides a variety of specialized memory areas, including
inputs (I), outputs (Q) and bit memory (M). This memory is accessible by all code blocks
without restriction.
● Data block (DB): You can include DBs in your user program to store data for the code
blocks. The data stored persists when the execution of the associated code block comes
to an end. A "global" DB stores data that can be used by all code blocks, while an
instance DB stores data for a specific FB and is structured by the parameters for the FB.
● Temp memory: Whenever a code block is called, the operating system of the CPU
allocates the temporary, or local, memory (L) to be used during the execution of the
block. When the execution of the code block finishes, the CPU reallocates the local
memory for the execution of other code blocks.
Each different memory location has a unique address. Your user program uses these
addresses to access the information in the memory location.
References to the input (I) or output (Q) memory areas, such as I0.3 or Q1.7, access the
process image. To immediately access the physical input or output, append the reference
with ":P" (such as I0.3:P, Q1.7:P, or "Stop:P").
Forcing applies a fixed value to a physical input (Ix.y:P) or a physical output (Qx.y:P) only.
To force an input or output, append a ":P" to the PLC tag or the address. For more
information, see "Forcing variables in the CPU" (Page 261).

Table 4- 4

Memory areas

Memory area

Description

Force

Retentive

I
Process image input

Copied from physical inputs at the beginning of the scan
cycle

I_:P1
(Physical input)

Immediate read of the physical input points on the CPU,
SB, and SM

Yes

Q
Process image output

Copied to physical outputs at the beginning of the scan
cycle

Q_:P1
(Physical output)

Immediate write to the physical output points on the
CPU, SB, and SM

Yes

M
Bit memory

Control and data memory

Yes
(optional)

L
Temp memory

Temporary data for a block local to that block

DB
Data block

Data memory and also parameter memory for FBs

Yes
(optional)

To immediately access (or to force) the physical inputs and physical outputs, append a ":P" to the address or tag (such
as I0.3:P, Q1.7:P, or "Stop:P").
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Each different memory location has a unique address. Your user program uses these
addresses to access the information in the memory location. The absolute address consists
of the following elements:
● Memory area (such as I, Q, or M)
● Size of the data to be accessed (such as "B" for Byte or "W" for Word)
● Address of the data (such as Byte 3 or Word 3)
When accessing a bit in the address for a Boolean value, you do not enter a mnemonic for
the size. You enter only the memory area, the byte location, and the bit location for the data
(such as I0.0, Q0.1, or M3.4).
Absolute address of a memory area:
A

Memory area identifier

Byte address: byte 3

Separator ("byte.bit")

Bit location of the byte (bit 4 of 8)

Bytes of the memory area

Bits of the selected byte

In the example, the memory area and byte address (M = bit memory area, and 3 = Byte 3)
are followed by a period (".") to separate the bit address (bit 4).

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Configuring the I/O in the CPU and I/O modules
When you add a CPU and I/O modules to your
configuration screen, I and Q addresses are
automatically assigned. You can change the
default addressing by selecting the address field in
the device configuration and typing new numbers.
• Digital inputs and outputs are assigned in
groups of 8 points (1 byte), whether the module
uses all the points or not.
• Analog inputs and outputs are assigned in
groups of 2 points (4 bytes).

The figure shows an example of a CPU 1214C with two SMs and one SB. In this example,
you could change the address of the DI8 module to 2 instead of 8. The tool assists you by
changing address ranges that are the wrong size or conflict with other addresses.

4.4.3

Accessing a "slice" of a tagged data type
PLC tags and data block tags can be accessed at the bit, byte, or word level depending on
their size. The syntax for accessing such a data slice is as follows:
● "".xn (bit access)
● "".bn (byte access)
● "".wn (word access)
● ""..xn (bit access)
● ""..bn (byte access)
● ""..wn (word access)
A double word-sized tag can be accessed by bits 0 - 31, bytes 0 - 3, or word 0 - 1. A wordsized tag can be accessed by bits 0 - 15, bytes 0 - 1, or word 0. A byte-sized tag can be
accessed by bits 0 - 7, or byte 0. Bit, byte, and word slices can be used anywhere that bits,
bytes, or words are expected operands.

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Note
Valid data types that can be accessed by slice are Byte, Char, Conn_Any, Date, DInt,
DWord, Event_Any, Event_Att, Hw_Any, Hw_Device, HW_Interface, Hw_Io, Hw_Pwm,
Hw_SubModule, Int, OB_Any, OB_Att, OB_Cyclic, OB_Delay, OB_WHINT, OB_PCYCLE,
OB_STARTUP, OB_TIMEERROR, OB_Tod, Port, Rtm, SInt, Time, Time_Of_Day, UDInt,
UInt, USInt, and Word. PLC Tags of type Real can be accessed by slice, but data block tags
of type Real cannot.

Examples
In the PLC tag table, "DW" is a declared tag of type DWORD. The examples show bit, byte,
and word slice access:
LAD

FBD

Bit access

SCL
IF "DW".x11 THEN
...
END_IF;

Byte access

IF "DW".b2 = "DW".b3
THEN
...
END_IF;

Word access

out:= "DW".w0 AND
"DW".w1;

4.4.4

Accessing a tag with an AT overlay
The AT tag overlay allows you to access an already-declared tag of a standard access block
with an overlaid declaration of a different data type. You can, for example, address the
individual bits of a tag of a Byte, Word, or DWord data type with an Array of Bool.

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Declaration
To overlay a parameter, declare an additional parameter directly after the parameter that is
to be overlaid and select the data type "AT". The editor creates the overlay, and you can
then choose the data type, struct, or array that you wish to use for the overlay.

Example
This example shows the input parameters of a standard-access FB. The byte tag B1 is
overlaid with an array of Booleans:

Table 4- 5

Overlay of a byte with a Boolean array

AT[0]

AT[1]

AT[2]

AT[3]

AT[4]

AT[5]

AT[6]

AT[7]

Another example is a DWord tag overlaid with a Struct:

The overlay types can be addressed directly in the program logic:
LAD

FBD

SCL
IF #AT[1] THEN
...
END_IF;
IF (#DW1_Struct.S1 =
W#16#000C) THEN
...
END_IF;
out1 := #DW1_Struct.S2;

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Rules
● Overlaying of tags is only possible in FB and FC blocks with standard access.
● You can overlay parameters for all block types and all declaration sections.
● An overlaid parameter can be used like any other block parameter.
● You cannot overlay parameters of type VARIANT.
● The size of the overlaying parameter must be less than or equal to the size of the overlaid
parameter.
● The overlaying variable must be declared immediately after the variable that it overlays
and identified with the keyword "AT".

4.5

Pulse outputs
The CPU or signal board (SB) can be configured to provide four pulse generators for
controlling high-speed pulse output functions, either as pulse-width modulation (PWM) or as
pulse-train output (PTO). The basic motion instructions use PTO outputs. You can assign
each pulse generator to either PWM or PTO, but not both at the same time.
Pulse outputs cannot be used by other instructions in the
user program. When you configure the outputs of the
CPU or SB as pulse generators, the corresponding
output addresses are removed from the Q memory and
cannot be used for other purposes in your user program.
If your user program writes a value to an output used as
a pulse generator, the CPU does not write that value to
the physical output.

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4.5 Pulse outputs

Note
Do not exceed the maximum pulse frequency.
The maximum pulse frequency of the pulse output generators is 1 MHz for the CPU 1217C
and 100 KHz for CPUs 1211C, 1212C, 1214C, and 1215C; 20 KHz (for a standard SB); or
200 KHz (for a high-speed SB).
The four pulse generators have default I/O assignments; however, they can be configured to
any digital output on the CPU or SB. Pulse generators on the CPU cannot be assigned to
distributed I/O.
When configuring the basic motion instructions, be aware that STEP 7 does not alert you if
you configure an axis with a maximum speed or frequency that exceeds this hardware
limitation. This could cause problems with your application, so always ensure that you do not
exceed the maximum pulse frequency of the hardware.
You can use onboard CPU outputs, or you can use the optional signal board outputs. The
output point numbers are shown in the following table (assuming the default output
configuration). If you have changed the output point numbering, then the output point
numbers will be those you assigned. Note that PWM requires only one output, while PTO
can optionally use two outputs per channel. If an output is not required for a pulse function, it
is available for other uses.
The four pulse generators have default I/O assignments; however, they can be configured to
any digital output on the CPU or SB. Pulse generators on the CPU cannot be assigned to
SMs or to distributed I/O.
Table 4- 6

Default output assignments for the pulse generators
Description

Pulse

Direction

Built-in I/O

Q0.0

Q0.1

SB I/O

Q4.0

Q4.1

Built-in outputs

Q0.0

SB outputs

Q4.0

Built-in I/O

Q0.2

Q0.3

SB I/O

Q4.2

Q4.3

Built-in outputs

Q0.2

SB outputs

Q4.2

Built-in I/O

Q0.41

Q0.51

SB I/O

Q4.0

Q4.1

Built-in outputs

Q0.41

SB outputs

Q4.1

PTO1

PWM1

PTO2

PWM2

PTO3

PWM3

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Description

Pulse

Direction

Built-in I/O

Q0.62

Q0.72

SB I/O

Q4.2

Q4.3

Built-in outputs

Q0.62

SB outputs

Q4.3

PTO4

PWM4

The CPU 1211C does not have outputs Q0.4, Q0.5, Q0.6, or Q0.7. Therefore, these outputs
cannot be used in the CPU 1211C.

The CPU 1212C does not have outputs Q0.6 or Q0.7. Therefore, these outputs cannot be used in
the CPU 1212C.

This table applies to the CPU 1211C, CPU 1212C, CPU 1214C, CPU 1215C, and CPU 1217C
PTO/PWM functions.

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You create the device configuration for your PLC by adding a CPU and additional modules to
your project.

①
②
③
④
⑤

Communications module (CM) or communication processor (CP): Up to 3, inserted in slots
101, 102, and 103
CPU: Slot 1
Ethernet port of CPU
Signal board (SB), communication board (CB) or battery board (BB): up to 1, inserted in the
CPU
Signal module (SM) for digital or analog I/O: up to 8, inserted in slots 2 through 9
(CPU 1214C, CPU 1215C and CPU 1217C allow 8, CPU 1212C allows 2, CPU 1211C does
not allow any)

To create the device configuration, add a
device to your project.
• In the Portal view, select "Devices &
Networks" and click "Add device".

• In the Project view, under the project
name, double-click "Add new device".

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5.1 Detecting the configuration for an unspecified CPU

5.1

Detecting the configuration for an unspecified CPU
If you are connected to a CPU, you can upload the
configuration of that CPU, including any modules, to your
project. Simply create a new project and select the "unspecified
CPU" instead of selecting a specific CPU. (You can also skip
the device configuration entirely by selecting the "Create a PLC
program" from the "First steps". STEP 7 then automatically
creates an unspecified CPU.)
From the program editor, you select the "Hardware detection"
command from the "Online" menu.

From the device configuration editor, you select the option for detecting the configuration of
the connected device.

After you select the CPU from the online dialog and click the Load button, STEP 7 uploads
the hardware configuration from the CPU, including any modules (SM, SB, or CM). You can
then configure the parameters for the CPU and the modules (Page 76).

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5.2 Adding a CPU to the configuration

5.2

Adding a CPU to the configuration
You create your device configuration by inserting
a CPU into your project. Select the CPU in the
"Add a new device" dialog and click "OK" to add
the CPU to the project.

The Device view shows the
CPU and rack.

Selecting the CPU in the Device view
displays the CPU properties in the
inspector window. Use these properties
to configure the operational parameters
of the CPU (Page 76).

Note
The CPU does not have a pre-configured IP address. You must manually assign an IP
address for the CPU during the device configuration. If your CPU is connected to a router on
the network, you also enter the IP address for a router.

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5.3 Changing a device

5.3

Changing a device
You can change the device type of a configure CPU or module. From Device configuration,
right-click the device and select "Change device" from the context menu. From the dialog,
navigate to and select the CPU or module that you want to replace. The Change device
dialog shows you combatibility information between the two devices.
Note
Device exchange: replacing a V3.0 CPU with a V4.0 CPU
You can open a STEP 7 V12 project in STEP 7 V13 and replace V3.0 CPUs with V4.0
CPUs. You cannot replace CPUs that are from versions prior to V3.0. When you replace a
V3.0 CPU with a V4.0 CPU, consider the differences (Page 345) in features and behavior
between the two versions, and actions you must take.
If you have a project for a CPU version older than V3.0, you can upgrade that project first to
V3.0 and then upgrade the V3.0 project to V4.0.

5.4

Adding modules to the configuration
Use the hardware catalog to add modules to the CPU:
● Signal module (SM) provides additional digital or analog I/O points. These modules are
connected to the right side of the CPU.
● Signal board (SB) provides just a few additional I/O points for the CPU. The SB is
installed on the front of the CPU.
● Battery Board 1297 (BB) provides long-term backup of the realtime clock. The BB is
installed on the front of the CPU.
● Communication board (CB) provides an additional communication port (such as RS485).
The CB is installed on the front of the CPU.
● Communication module (CM) and communication processor (CP) provide an additional
communication port, such as for PROFIBUS or GPRS. These modules are connected to
the left side of the CPU.
To insert a module into the device configuration, select the module in the hardware catalog
and either double-click or drag the module to the highlighted slot. You must add the modules
to the device configuration and download the hardware configuration to the CPU for the
modules to be functional.

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5.4 Adding modules to the configuration
Table 5- 1
Module

Adding a module to the device configuration
Select the module

Insert the module

Result

SB, BB or
CB

CM or CP

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5.5 Configuring the operation of the CPU and modules

5.5

Configuring the operation of the CPU and modules
To configure the operational parameters for the CPU, select the CPU in the Device view and
use the "Properties" tab of the inspector window.
You can configure the following CPU properties:
• PROFINET IP address and time
synchronization for the CPU
• Startup behavior of the CPU following an OFFto-ON power transition
• Local (on-board) digital and analog I/O, highspeed counters (HSC), and pulse generators
• System clock (time, time zone and daylight
saving time)
• Read/write protection and password for
accessing the CPU
• Maximum cycle time or a fixed minimum cycle
time and communications load
• Web server properties

Configuring the STOP-to-RUN operation of the CPU
Whenever the operating state changes from STOP to RUN, the CPU clears the process
image inputs, initializes the process image outputs, and processes the startup OBs.
(Therefore, any read accesses to the process-image inputs by instructions in the startup OBs
will read zero rather than the current physical input value.) To read the current state of a
physical input during startup, you must perform an immediate read. The startup OBs and any
associated FCs and FBs are executed next. If more than one startup OB exists, each is
executed in order according to the OB number, with the lowest OB number executing first.
The CPU also performs the following tasks during the startup processing.
● Interrupts are queued but not processed during the startup phase
● No cycle time monitoring is performed during the startup phase
● Configuration changes to HSC (high-speed counter), PWM (pulse-width modulation), and
PtP (point-to-point communication) modules can be made in startup
● Actual operation of HSC, PWM, and point-to-point communication modules only occurs in
RUN
After the execution of the startup OBs finishes, the CPU goes to RUN mode and processes
the control tasks in a continuous scan cycle.
Use the CPU properties to configure how the CPU starts up after a power cycle.

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5.5 Configuring the operation of the CPU and modules

• In STOP mode
• In RUN mode
• In the previous
mode (prior to the
power cycle)

The CPU performs a warm restart before going to RUN mode. Warm restart resets all nonretentive memory to the default start values, but the CPU retains the current values stored in
the retentive memory.
Note
The CPU always performs a restart after a download
Whenever you download an element of your project (such as a program block, data block, or
hardware configuration), the CPU performs a restart on the next transition to RUN mode. In
addition to clearing the inputs, initializing the outputs and initializing the non-retentive
memory, the restart also initializes the retentive memory areas.
After the restart that follows a download, all subsequent STOP-to-RUN transitions perform a
warm restart (that does not initialize the retentive memory).

5.5.1

System memory and clock memory provide standard functionality
You use the CPU properties to enable bytes for "system memory" and "clock memory". Your
program logic can reference the individual bits of these functions by their tag names.
● You can assign one byte in M memory for system memory. The byte of system memory
provides the following four bits that can be referenced by your user program by the
following tag names:
– First cycle: (Tag name "FirstScan") bit is set to1 for the duration of the first scan after
the startup OB finishes. (After the execution of the first scan, the "first scan" bit is set
to 0.)
– Diagnostics status changed (Tag name: "DiagStatusUpdate") is set to 1 for one scan
after the CPU logs a diagnostic event. Because the CPU does not set the "diagnostic
graph changed" bit until the end of the first execution of the program cycle OBs, your
user program cannot detect if there has been a diagnostic change either during the
execution of the startup OBs or the first execution of the program cycle OBs.
– Always 1 (high): (Tag name "AlwaysTRUE") bit is always set to 1.
– Always 0 (low): (Tag name "AlwaysFALSE") bit is always set to 0.
● You can assign one byte in M memory for clock memory. Each bit of the byte configured
as clock memory generates a square wave pulse. The byte of clock memory provides 8
different frequencies, from 0.5 Hz (slow) to 10 Hz (fast). You can use these bits as control
bits, especially when combined with edge instructions, to trigger actions in the user
program on a cyclic basis.

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The CPU initializes these bytes on the transition from STOP mode to STARTUP mode. The
bits of the clock memory change synchronously to the CPU clock throughout the STARTUP
and RUN modes.
CAUTION
Risks with overwriting the system memory or clock memory bits
Overwriting the system memory or clock memory bits can corrupt the data in these
functions and cause your user program to operate incorrectly, which can cause damage to
equipment and injury to personnel.
Because both the clock memory and system memory are unreserved in M memory,
instructions or communications can write to these locations and corrupt the data.
Avoid writing data to these locations to ensure the proper operation of these functions, and
always implement an emergency stop circuit for your process or machine.
System memory configures a byte with bits that turn on (value = 1) for a specific event.

Table 5- 2
7

System memory
5

Reserved

Always off

Always on

First scan indicator

Value 0

Value 1

Diagnostic status
indicator
•

1: Change

•

0: No change

•

1: First scan after
startup

•

0: Not first scan

Clock memory configures a byte that cycles the individual bits on and off at fixed intervals.
Each clock bit generates a square wave pulse on the corresponding M memory bit. These
bits can be used as control bits, especially when combined with edge instructions, to trigger
actions in the user code on a cyclic basis.

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Table 5- 3

Clock memory

Bit number

Period (s)

2.0

1.6

1.0

0.8

0.5

0.4

0.2

0.1

Frequency (Hz)

0.5

0.625

1.25

2.5

Tag name

Because clock memory runs asynchronously to the CPU cycle, the status of the clock memory can change several times
during a long cycle.

Configuring the operation of the I/O and communication modules
To configure the operational parameters for the signal module (SM), signal board (SB), or
communication module (CM), select the module in the Device view and use the "Properties"
tab of the inspector window.
Signal module (SM) and signal board (SB)
• Digital I/O: Configure the individual inputs, such as
for Edge detection and "pulse catch" (to stay on or
off for one scan after a momentary high- or low
pulse). Configure the outputs to use a freeze or
substitute value on a transition from RUN mode to
STOP mode.
● Analog I/O: Configure the parameters for individual inputs (such as voltage / current,
range and smoothing) and also enable underflow or overflow diagnostics. Configure the
parameters for individual analog outputs and enable diagnostics, such as short-circuit (for
voltage outputs) or overflow values.
● I/O addresses: Configure the start address for the set of inputs and outputs of the
module.

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Communication module (CM) and communication
board (CB)
• Port configuration: Configure the communication
parameters, such as baud rate, parity, data bits,
stop bits, and wait time.
● Transmit and receive message: Configure options related to transmitting and receiving
data (such as the message-start and message-end parameters)
You can also change these configuration parameters with your user program.

5.6

Configuring the IP address of the CPU
Because the CPU does not have a pre-configured IP address, you must manually assign an
IP address. You configure the IP address and the other parameters for the PROFINET
interface when you configure the properties for the CPU.
● In a PROFINET network, each device is assigned a unique Media Access Control
address (MAC address) by the manufacturer for identification. Each device must also
have an IP address.
● A subnet is a logical grouping of connected network devices. A mask (also known as the
subnet mask or network mask) defines the boundaries of a subnet. The only connection
between different subnets is via a router. Routers are the link between LANs and rely on
IP addresses to deliver and receive data packets.
Before you can download an IP address to the CPU, you must ensure that the IP address for
your CPU is compatible with the IP address of your programming device.
You can use STEP 7 to determine the IP address of your programming device:
1. Expand the "Online access" folder in the Project tree to display your networks.
2. Select the network that connects to the CPU.
3. Right-click the specific network to display the context menu.
4. Select the "Properties" command.
Note
The IP address for the CPU must be compatible with the IP address and subnet mask for
the programming device. Consult your network specialist for a suitable IP address and
subnet mask for your CPU.

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The "Properties" window displays
the settings for the programming
device.

After determining the IP address
and subnet mask for the CPU,
enter the IP address for the CPU
and for the router (if applicable).
Refer to the S7-1200 System
Manual for more information.

After completing the configuration,
download the project to the CPU.
The IP addresses for the CPU and
for the router (if applicable) are
configured when you download the
project.

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5.7

Protecting access to the CPU or code block is easy
The CPU provides four levels of security for restricting access to specific functions. When
you configure the security level and password for a CPU, you limit the functions and memory
areas that can be accessed without entering a password.
Each level allows certain functions to be accessible without a password. The default
condition for the CPU is to have no restriction and no password-protection. To restrict access
to a CPU, you configure the properties of the CPU and enter the password.
Entering the password over a network does not compromise the password protection for the
CPU. Password protection does not apply to the execution of user program instructions
including communication functions. Entering the correct password provides access to all of
the functions at that level.
PLC-to-PLC communications (using communication instructions in the code blocks) are not
restricted by the security level in the CPU.

Table 5- 4

Security levels for the CPU

Security level

Access restrictions

Full access (no
protection)

Allows full access without password protection.

Read access

Allows HMI access and all forms of PLC-to-PLC communications without password protection.
Password is required for modifying (writing to) the CPU and for changing the CPU mode
(RUN/STOP).

HMI access

Allows HMI access and all forms of PLC-to-PLC communications without password protection.
Password is required for reading the data in the CPU, for modifying (writing to) the CPU, and for
changing the CPU mode (RUN/STOP).

No access (complete
protection)

Allows no access without password protection.
Password is required for HMI access, reading the data in the CPU, for modifying (writing to) the
CPU, and for changing the CPU mode (RUN/STOP)

Passwords are case-sensitive. To configure the protection level and passwords, follow these
steps:
1. In the "Device configuration", select the CPU.
2. In the inspector window, select the "Properties" tab.
3. Select the "Protection" property to select the protection level and to enter passwords.

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When you download this configuration to the CPU, the user has HMI access and can access
HMI functions without a password. To read data, the user must enter the configured
password for "Read access" or the password for "Full access (no protection)". To write data,
the user must enter the configured password for "Full access (no protection)".
WARNING
Unauthorized access to a protected CPU
Users with CPU full access privileges have privileges to read and write PLC variables.
Regardless of the access level for the CPU, Web server users can have privileges to read
and write PLC variables. Unauthorized access to the CPU or changing PLC variables to
invalid values could disrupt process operation and could result in death, severe personal
injury and/or property damage.
Authorized users can perform operating mode changes, writes to PLC data, and firmware
updates. Siemens recommends that you observe the following security practices:
• Password protect CPU access levels and Web server user IDs with strong passwords.
Strong passwords are at least eight characters in length, mix letters, numbers, and
special characters, are not words that can be found in a dictionary, and are not names
or identifiers that can be derived from personal information. Keep the password secret
and change it frequently.
• Enable access to the Web server only with the HTTPS protocol.
• Do not extend the default minimum privileges of the Web server "Everybody" user.
• Perform error-checking and range-checking on your variables in your program logic
because Web page users can change PLC variables to invalid values.

Connection mechanisms
To access remote connection partners with PUT/GET instructions, the user must also have
permission.
By default, the "Permit access with PUT/GET communication" option is not enabled. In this
case, read and write access to CPU data is only possible for communication connections
that require configuration or programming both for the local CPU and for the communication
partner. Access through BSEND/BRCV instructions is possible, for example.
Connections for which the local CPU is only a server (meaning that no
configuration/programming of the communication with the communication partner exists at
the local CPU), are therefore not possible during operation of the CPU, for example:
● PUT/GET, FETCH/WRITE or FTP access through communication modules
● PUT/GET access from other S7 CPUs
● HMI access through PUT/GET communication
If you want to allow access to CPU data from the client side, that is, you do not want to
restrict the communication services of the CPU, follow these steps:
1. Configure the protection access level to be any level other than "No access (complete
protection)".
2. Select the "Permit access with PUT/GET communication" check box.

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When you download this configuration to the CPU, the CPU permits PUT/GET
communication from remote partners

5.7.1

Know-how protection
Know-how protection allows you to prevent one or more code blocks (OB, FB, FC, or DB) in
your program from unauthorized access. You create a password to limit access to the code
block. The password-protection prevents unauthorized reading or modification of the code
block. Without the password, you can read only the following information about the code
block:
● Block title, block comment, and block properties
● Transfer parameters (IN, OUT, IN_OUT, Return)
● Call structure of the program
● Global tags in the cross references (without information on the point of use), but local
tags are hidden
When you configure a block for "know-how" protection, the code within the block cannot be
accessed except after entering the password.
Use the "Properties" task card of the code block to configure the know-how protection for
that block. After opening the code block, select "Protection" from Properties.

1. In the Properties for the code block, click
the "Protection" button to display the
"Know-how protection" dialog.
2. Click the "Define" button to enter the
password.

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After entering and confirming the password,
click "OK".

5.7.2

Copy protection
An additional security feature allows you to bind program blocks for use with a specific
memory card or CPU. This feature is especially useful for protecting your intellectual
property. When you bind a program block to a specific device, you restrict the program or
code block for use only with a specific memory card or CPU. This feature allows you to
distribute a program or code block electronically (such as over the Internet or through email)
or by sending a memory cartridge. Copy protection is available for OBs, FBs, and FCs.
Use the "Properties" task card of the code block to bind the block to a specific CPU or
memory card.

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1. After opening the code block, select "Protection".

2. From the drop-down list under "Copy protection" task, select the option to bind the code
block either to a memory card or to a specific CPU.

3. Select the type of copy protection and enter the serial number for the memory card or
CPU.
Note
The serial number is case-sensitive.

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6.1

Easy to design your user program
When you create a user program for the automation tasks, you insert the instructions for the
program into code blocks (OB, FB, or FC).

Choosing the type of structure for your user program
Based on the requirements of your application, you can choose either a linear structure or a
modular structure for creating your user program.
● A linear program executes all of the instructions for your automation tasks in sequence,
one after the other. Typically, the linear program puts all of the program instructions into
one program cycle OB (such as OB 1) for cyclic execution of the program.
● A modular program calls specific code blocks that perform specific tasks. To create a
modular structure, you divide the complex automation task into smaller subordinate tasks
that correspond to the functional tasks being performed by the process. Each code block
provides the program segment for each subordinate task. You structure your program by
calling one of the code blocks from another block.
Linear structure:

Modular structure:

By designing FBs and FCs to perform generic tasks, you create modular code blocks. You
then structure your user program by having other code blocks call these reusable modules.
The calling block passes device-specific parameters to the called block. When a code block
calls another code block, the CPU executes the program code in the called block. After
execution of the called block is complete, the CPU resumes the execution of the calling
block. Processing continues with execution of the instruction that follows after the block call.
You can also assign an OB to an interrupting event. When the event occurs, the CPU
executes the program code in the associated OB. After the execution of the OB is complete,
the CPU resumes the execution at the point in the user program when the interrupting event
occurred, which could be any point in the scan.

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Calling block (or interrupted block)

Called FB or BC (or interrupting OB)

①
②

Program execution

③
④

Program execution

Instruction (or interrupting event) that initiates
the execution of another block
Block end (returns to calling block)

You can nest the block calls for a more modular structure. In the following example, the
nesting depth is 3: the program cycle OB plus 3 layers of calls to code blocks.

①
②

Start of cycle
Nesting depth

By creating generic code blocks that can be reused within the user program, you can simplify
the design and implementation of the user program.
● You can create reusable blocks of code for standard tasks, such as for controlling a pump
or a motor. You can also store these generic code blocks in a library that can be used by
different applications or solutions.
● When you structure the user program into modular components that relate to functional
tasks, the design of your program can be easier to understand and to manage. The
modular components not only help to standardize the program design but can also help
to make updating or modifying the program code quicker and easier.
● Creating modular components simplifies the debugging of your program. By structuring
the complete program as a set of modular program segments, you can test the
functionality of each code block as it is developed.
● Utilizing a modular design that relates to specific functional tasks can reduce the time
required for the commissioning of the completed application.

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6.1.1

Use OBs for organizing your user program
Organization blocks provide structure for your program. They serve as the interface between
the operating system and the user program. OBs are event driven. An event, such as a
diagnostic interrupt or a time interval, causes the CPU to execute an OB. Some OBs have
predefined start events and behavior.
The program cycle OB contains your main program. You can include more than one program
cycle OB in your user program. During RUN mode, the program cycle OBs execute at the
lowest priority level and can be interrupted by all other event types. The startup OB does not
interrupt the program cycle OB because the CPU executes the startup OB before going to
RUN mode.
After finishing the processing of the program cycle OBs, the CPU immediately executes the
program cycle OBs again. This cyclic processing is the "normal" type of processing used for
programmable logic controllers. For many applications, the entire user program is located in
a single program cycle OB.
You can create other OBs to perform specific functions, such as for handling interrupts and
errors, or for executing specific program code at specific time intervals. These OBs interrupt
the execution of the program cycle OBs.
Use the "Add new block" dialog to create new OBs in your user program.
Interrupt handling is always
event-driven. When such
an event occurs, the CPU
interrupts the execution of
the user program and calls
the OB that was configured
to handle that event. After
finishing the execution of
the interrupting OB, the
CPU resumes the
execution of the user
program at the point of
interruption.

The CPU determines the order for handling interrupt events by priority. You can assign
multiple interrupt events to the same priority class. For more information, refer to the topics
on organization blocks (Page 55) and execution of the user program (Page 53).

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Creating additional OBs
You can create multiple OBs for your user program, even for the program cycle and startup
OB events. Use the "Add new block" dialog to create an OB and enter a name for your OB.
If you create multiple program cycle OBs for your user program, the CPU executes each
program cycle OB in numerical sequence, starting with the program cycle OB with the lowest
number (such as OB 1). For example: after the first program cycle OB (such as OB 1)
finishes, the CPU executes the program cycle OB with the next higher number.

Configuring the properties of an OB
You can modify the properties of an
OB. For example, you can configure the
OB number or programming language.

Note
Note that you can assign a process image part number to an OB that corresponds to PIP0,
PIP1, PIP2, PIP3, or PIP4. If you enter a number for the process image part number, the
CPU creates that process image partition. See the topic "Execution of the user program
(Page 53)" for an explanation of the process image partitions.

6.1.2

FBs and FCs make programming the modular tasks easy
A function (FC) is like a subroutine. An FC is a code block that typically performs a specific
operation on a set of input values. The FC stores the results of this operation in memory
locations. Use FCs to perform the following tasks:
● To perform standard and reusable operations, such as for mathematical calculations
● To perform functional tasks, such as for individual controls using bit logic operations
An FC can also be called several times at different points in a program. This reuse simplifies
the programming of frequently recurring tasks.
Unlike an FB, an FC does not have an associated instance DB. The FC uses its temp
memory (L) for the data used to calculate the operation. The temporary data is not saved. To
store data for use after the execution of the FC has finished, assign the output value to a
global memory location, such as M memory or to a global DB.

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A function block (FB) is like a subroutine with memory. An FB is a code block whose calls
can be programmed with block parameters. The FB stores the input (IN), output (OUT), and
in/out (IN_OUT) parameters in variable memory that is located in a data block (DB), or
"instance" DB. The instance DB provides a block of memory that is associated with that
instance (or call) of the FB and stores data after the FB finishes.
You typically use an FB to control the operation for tasks or devices that do not finish their
operation within one scan cycle. To store the operating parameters so that they can be
quickly accessed from one scan to the next, each FB in your user program has one or more
instance DBs. When you call an FB, you also open an instance DB that stores the values of
the block parameters and the static local data for that call or "instance" of the FB. These
values are stored in the instance DB after the FB finishes.
You can assign start values to the parameters in the FB interface. These values are
transferred to the associated instance DB. If you do not assign parameters, the values
currently stored in the instance DB will be used. In some cases, you must assign
parameters.
You can associate different instance DBs with different calls of the FB. The instance DBs
allow you to use one generic FB to control multiple devices. You structure your program by
having one code block make a call to an FB and an instance DB. The CPU then executes
the program code in that FB and stores the block parameters and the static local data in the
instance DB. When the execution of the FB finishes, the CPU returns to the code block that
called the FB. The instance DB retains the values for that instance of the FB. By designing
the FB for generic control tasks, you can reuse the FB for multiple devices by selecting
different instance DBs for different calls of the FB.
The following figure shows an OB that calls one FB three times, using a different data block
for each call. This structure allows one generic FB to control several similar devices, such as
motors, by assigning a different instance data block for each call for the different devices.

Each instance DB stores the data (such as speed, ramp-up time, and total operating time)
for an individual device. In this example, FB 22 controls three separate devices, with DB 201
storing the operational data for the first device, DB 202 storing the operational data for the
second device, and DB 203 storing the operational data for the third device.

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6.1.3

Data blocks provide easy storage for program data
You create data blocks (DB) in your user program to store data for the code blocks. All of the
program blocks in the user program can access the data in a global DB, but an instance DB
stores data for a specific function block (FB).
Your user program can store data in the specialized memory areas of the CPU, such as for
the inputs (I), outputs (Q), and bit memory (M). In addition, you can use a data block (DB) for
fast access to data stored within the program itself.
The data stored in a DB is not deleted when the data block is closed or the execution of the
associated code block comes to an end. There are two types of DBs:
● A global DB stores data for the code blocks in your program. Any OB, FB, or FC can
access the data in a global DB.
● An instance DB stores the data for a specific FB. The structure of the data in an instance
DB reflects the parameters (Input, Output, and InOut) and the static data for the FB. The
Temp memory for the FB is not stored in the instance DB.
Although the instance DB reflects the data for a specific FB, any code block can access the
data in an instance DB.

6.1.4

Creating a new code block
1. Open "Program blocks" folder.
2. Double-click "Add new block".
3. In the "Add new block" dialog,
click the type of block to add.
For example, click the
"Function (FC)" icon to add an
FC.
4. Specify the programming
language for the code block by
selecting "LAD" from the dropdown menu.
5. Click "OK" to add the block to
the project.

Selecting the "Add new and open" option (default) opens the code block in the Project view.

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6.1.5

Creating reusable code blocks
Use the "Add new block"
dialog under "Program
blocks" in the Project
navigator to create OBs,
FBs, FCs, and global DBs.
When you create a code
block, you select the
programming language for
the block. You do not
select a language for a DB
because it only stores data.
Selecting the "Add new
and open" check box
(default) opens the code
block in the Project view.

You can store objects you want to reuse in libraries. For each project, there is a project
library that is connected to the project. In addition to the project library, you can create any
number of global libraries that can be used over several projects. Since the libraries are
compatible with each other, library elements can be copied and moved from one library to
another.
Libraries are used, for example, to create templates for blocks that you first paste into the
project library and then further develop there. Finally, you copy the blocks from the project
library to a global library. You make the global library available to other colleagues working
on your project. They use the blocks and further adapt them to their individual requirements,
where necessary.
For details about library operations, refer to the STEP 7 online Help library topics.

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6.2 Easy-to-use programming languages

6.1.6

Calling a code block from another code block
You can easily have any code block (OB,
FB, or FC) in your user program call an FB
or FC in your CPU.
1. Open the code block that will call the other block.
2. In the project tree, select the code block to be called.
3. Drag the block to the selected network to create a call to the code block.
Note
Your user program cannot call an OB because OBs are event-driven (Page 55). The CPU
starts the execution of the OB in response to receiving an event.

6.2

Easy-to-use programming languages
STEP 7 provides the following standard programming languages for S7-1200:
● LAD (ladder logic) is a graphical programming language. The representation is based on
circuit diagrams.
● FBD (Function Block Diagram) is a programming language that is based on the graphical
logic symbols used in Boolean algebra.
● SCL (structured control language) is a text-based, high-level programming language.
When you create a code block, you select the programming language to be used by that
block.
Your user program can utilize code blocks created in any or all of the programming
languages.

6.2.1

Ladder logic (LAD)
The elements of a circuit diagram, such as normally closed and normally open contacts, and
coils are linked to form networks.

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To create the logic for complex operations, you can insert branches to create the logic for
parallel circuits. Parallel branches are opened downwards or are connected directly to the
power rail. You terminate the branches upwards.
LAD provides "box" instructions for a variety of functions, such as math, timer, counter, and
move.
STEP 7 does not limit the number of instructions (rows and columns) in a LAD network.
Note
Every LAD network must terminate with a coil or a box instruction.
Consider the following rules when creating a LAD network:
● You cannot create a branch that could result in a power flow in the reverse direction.

● You cannot create a branch that would cause a short circuit.

6.2.2

Function Block Diagram (FBD)
Like LAD, FBD is also a graphical programming language. The representation of the logic is
based on the graphical logic symbols used in Boolean algebra.
To create the logic for complex operations,
insert parallel branches between the boxes.

Mathematical functions and other complex functions can be represented directly in
conjunction with the logic boxes.
STEP 7 does not limit the number of instructions (rows and columns) in an FBD network.

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6.2.3

SCL overview
Structured Control Language (SCL) is a high-level, PASCAL-based programming language
for the SIMATIC S7 CPUs. SCL supports the block structure of STEP 7. You can also
include program blocks written in SCL with program blocks written in LAD and FBD.
SCL instructions use standard programming operators, such as for assignment (:=),
mathematical functions (+ for addition, - for subtraction, * for multiplication, and / for division).
SCL uses standard PASCAL program control operations, such as IF-THEN-ELSE, CASE,
REPEAT-UNTIL, GOTO and RETURN. You can use any PASCAL reference for syntactical
elements of the SCL programming language. Many of the other instructions for SCL, such as
timers and counters, match the LAD and FBD instructions.
Because SCL, like PASCAL, offers conditional processing, looping, and nesting control
structures, you can implement complex algorithms in SCL more easily than in LAD or FBD.
The following examples show different expressions for different uses:
"C" := #A+#B;

"Data_block_1".Tag := #A;

IF #A > #B THEN "C" := #A;

"C" := SQRT (SQR (#A) + SQR (#B));

Assigns two local variables to a tag
Assignment to a data block tag
Condition for the IF-THEN statement
Parameters for the SQRT instruction

As a high-level programming language, SCL uses standard statements for basic tasks:
● Assignment statement: :=
● Mathematical functions: +, -, *, and /
● Addressing of global variables (tags): "" (Tag name or data block name
enclosed in double quotes)
● Addressing of local variables: # (Variable name preceded by "#" symbol)
● Absolute addressing: %, for example %I0.0 or %MW10
Arithmetic operators can process various numeric data types. The data type of the result is
determined by the data type of the most-significant operands. For example, a multiplication
operation that uses an INT operand and a REAL operand yields a REAL value for the result.

6.2.4

SCL program editor
You can designate any type of block (OB, FB, or FC) to use the SCL programming language
at the time you create the block. STEP 7 provides an SCL program editor that includes the
following elements:
● Interface section for defining the parameters of the code block
● Code section for the program code
● Instruction tree that contains the SCL instructions supported by the CPU
You enter the SCL code for your instruction directly in the code section. The editor includes
buttons for common code constructs and comments. For more complex instructions, simply
drag the SCL instructions from the instruction tree and drop them into your program. You can
also use any text editor to create an SCL program and then import that file into STEP 7.

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In the Interface section of the SCL code block you can declare the following types of
parameters:
● Input, Output, InOut, and Ret_Val: These parameters define the input tags, output tags,
and return value for the code block. The tag name that you enter here is used locally
during the execution of the code block. You typically would not use the global tag name in
the tag table.
● Static (FBs only; the illustration above is for an FC): The code block uses static tags for
storage of static intermediate results in the instance data block. The block retains static
data until overwritten, which can be after several cycles. The names of the blocks, which
this block calls as multi-instance, are also stored in the static local data.
● Temp: These parameters are the temporary tags that are used during the execution of
the code block.
If you call the SCL code block from another code block, the parameters of the SCL code
block appear as inputs or outputs.

In this example, the tags for "Start" and "On" (from the project tag table) correspond to
"StartStopSwitch" and "RunYesNo" in the declaration table of the SCL program.

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6.3

Powerful instructions make programming easy

6.3.1

Providing the basic instructions you expect

Bit logic instructions
The basis of bit logic instruction is contacts and coils. Contacts read the status of a bit, while
the coils write the status of the operation to a bit.
Contacts test the binary status of
the bit, with the result being "power
flow" if on (1) or "no power flow" if
off (0).
The state of the coil reflects the
status of the preceding logic.
If you use a coil with the same address in more than one program location, the result of the
last calculation in the user program determines the status of the value that is written to the
physical output during the updating of the outputs.
Normally Open
Contact

Normally Closed
Contact

The Normally Open contact is closed (ON) when
the assigned bit value is equal to 1.
The Normally Closed contact is closed (ON) when
the assigned bit value is equal to 0.

The basic structure of a bit logic operation is either AND logic or OR logic. Contacts
connected in series create AND logic networks. Contacts connected in parallel create OR
logic networks.
You can connect contacts to other contacts and create your own combination logic. If the
input bit you specify uses memory identifier I (input) or Q (output), then the bit value is read
from the process-image register. The physical contact signals in your control process are
wired to input terminals on the PLC. The CPU scans the wired input signals and updates the
corresponding state values in the process-image input register.
You can specify an immediate read of a physical input using ":P" following the tag for an
input (such as "Motor_Start:P" or "I3.4:P"). For an immediate read, the bit data values are
read directly from the physical input instead of the process image. An immediate read does
not update the process image.
Output coil

Inverted output coil

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Note the following output results for power flow through output and inverted output coils:
● If there is power flow through an output coil, then the output bit is set to 1.
● If there is no power flow through an output coil, then the output coil bit is set to 0.
● If there is power flow through an inverted output coil, then the output bit is set to 0.
● If there is no power flow through an inverted output coil, then the output bit is set to 1.
The coil output instruction writes a value for an output bit. If the output bit you specify uses
memory identifier Q, then the CPU turns the output bit in the process-image register on or
off, setting the specified bit equal to power flow status. The output signals for your control
actuators are wired to the output terminals on the PLC. In RUN mode, the CPU system
scans your input signals, processes the input states according to your program logic, and
then reacts by setting new output state values in the process-image output register. After
each program execution cycle, the CPU transfers the new output state reaction stored in the
process-image register to the wired output terminals.
You can specify an immediate write of a physical output using ":P" following the tag for an
output (such as "Motor_On:P" or "Q3.4:P"). For an immediate write, the bit data values are
written to the process image output and directly to the physical output.
Coils are not restricted to the end of a network. You can insert a coil in the middle of a rung
of the LAD network, in between contacts or other instructions.
NOT contact inverter AND box with one inverted
(LAD)
logic input (FBD)

AND box with inverted logic input and
output (FBD)

The LAD NOT contact inverts the logical state of power flow input.
● If there is no power flow into the NOT contact, then there is power flow out.
● If there is power flow into the NOT contact, then there is no power flow out.
For FBD programming, you can drag the "Negate binary input" tool from the "Favorites"
toolbar or instruction tree and then drop it on an input or output to create a logic inverter on
that box connector.
AND box (FBD)

OR box (FBD)

XOR box (FBD)

● All inputs of an AND box must be TRUE for the output to be TRUE.
● Any input of an OR box must be TRUE for the output to be TRUE.
● An odd number of the inputs of an XOR box must be TRUE for the output to be TRUE.

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In FBD programming, the contact networks of LAD are represented by AND (&), OR (>=1),
and exclusive OR (x) box networks where you can specify bit values for the box inputs and
outputs. You may also connect to other logic boxes and create your own logic combinations.
After the box is placed in your network, you can drag the "Insert binary input" tool from the
"Favorites" toolbar or instruction tree and then drop it onto the input side of the box to add
more inputs. You can also right-click on the box input connector and select "Insert input".
Box inputs and output can be connected to another logic box, or you can enter a bit address
or bit symbol name for an unconnected input. When the box instruction is executed, the
current input states are applied to the binary box logic and, if true, the box output will be true.

6.3.2

Compare and Move instructions
The Compare instructions perform a comparison of two values with the same data type.

Table 6- 1
Instruction
LAD:

FBD:

Compare instructions
SCL
out
out
out
out
out
out

:=
:=
:=
:=
:=
:=

in1
in1
in1
in1
in1
in1

= in2;
<> in2;
>= in2;
<= in2;
> in2;
< in2;

Description
•

Equals (==):The comparison is true if IN1 is equal to
IN2

•

Not equal (<>):The comparison is true if IN1 is not
equal to IN2

•

Greater than or equal to (>=):The comparison is true if
IN1 is greater than or equal to IN2

•

Less than or equal to (<=):The comparison is true if
IN1 is less than or equal to IN2

•

Greater than (>):The comparison is true if IN1 is
greater than IN2

•

Less than (<):The comparison is true if IN1 is less
than IN2

For LAD and FBD: The contact is activated (LAD) or the box output is TRUE (FBD) if the comparison is TRUE,

The Move instructions copy data elements to a new memory address and can convert from
one data type to another. The source data is not changed by the move process.
● MOVE copies a data element stored at a specified address to a new address. To add
another output, click the icon next to the OUT1 parameter.
● MOVE_BLK (interruptible move) and UMOVE_BLK (uninterruptible move) copy a block of
data elements to a new address. The MOVE_BLK and UMOVE_BLK instructions have an
additional COUNT parameter. The COUNT specifies how many data elements are
copied. The number of bytes per element copied depends on the data type assigned to
the IN and OUT parameter tag names in the PLC tag table.

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Table 6- 2
LAD / FBD

6.3.3
Table 6- 3
LAD / FBD

MOVE, MOVE_BLK and UMOVE_BLK instructions
SCL

out1 := in;

Description
Copies a data element stored at a specified
address to a new address or multiple
addresses. To add another output in LAD or
FBD, click the icon by the output parameter.
For SCL, use multiple assignment statements.
You might also use one of the loop
constructions.

MOVE_BLK(in:=_variant_in,
count:=_uint_in,
out=>_variant_out);

Interruptible move that copies a block of data
elements to a new address.

UMOVE_BLK(in:=_variant_in,
count:=_uint_in
out=>_variant_out);

Uninterruptible move that copies a block of
data elements to a new address.

Conversion instructions
Conversion instructions
SCL
out := _TO_(in);

Description
Converts a data element from one data type to
another data type.

For LAD and FBD: Click below the box name and select the data types from the drop-down menu. After you select the
(convert from) data type, a list of possible conversions is shown in the (convert to) dropdown list.

For SCL: Construct the conversion instruction by identifying the data type for the input parameter (in) and output
parameter (out). For example, DWORD_TO_REAL converts a DWord value to a Real value.

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Table 6- 4
LAD / FBD

Round and Truncate instructions
SCL

out := ROUND (in);

Description
Converts a real number (Real or LReal) to an integer. The instruction
rounds the real number to the nearest integer value (IEEE - round to
nearest). If the number is exactly one-half the span between two
integers (for example, 10.5), then the instruction rounds the number to
the even integer. For example:
•

out := TRUNC(in);

Table 6- 5
LAD / FBD

ROUND (10.5) = 10

• ROUND (11.5) = 12
For LAD/FBD, you click the "???" in the instruction box to select the
data type for the output, for example, "DInt". For SCL, the default output
data type is DINT. To round to another output data type, enter the
instruction name with the explicit name of the data type, for example,
ROUND_REAL or ROUND_LREAL.
Converts a real number (Real or LReal) to an integer. The fractional
part of the real number is truncated to zero (IEEE - round to zero).

Ceiling (CEIL) and Floor instructions
SCL
out := CEIL(in);

Description

out := FLOOR(in);

Converts a real number (Real or LReal) to the closest integer smaller
than or equal to the selected real number (IEEE "round to -infinity").

Converts a real number (Real or LReal) to the closest integer greater
than or equal to the selected real number (IEEE "round to +infinity").

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Table 6- 6

SCALE_X and NORM_X instructions

LAD / FBD

SCL

Description

out := SCALE_X(
min,:=_undef_in_
value:=_real_in_,
max:=undef_in_);

Scales the normalized real parameter VALUE where ( 0.0
<= VALUE <= 1.0 ) in the data type and value range
specified by the MIN and MAX parameters:
OUT = VALUE (MAX - MIN) + MIN

out := NORM_X(
min:=_,undef_in_
value:=_undef_in_,
max:=_undef_in_);

OUT = (VALUE - MIN) / (MAX - MIN),
where ( 0.0 <= OUT <= 1.0 )

Equivalent SCL: out := value (max-min) + min;2 Equivalent SCL: out := (value-min)/(max-min);

6.3.4
Table 6- 7

Math made easy with the Calculate instruction
CALCULATE instruction

LAD / FBD

Table 6- 8

Normalizes the parameter VALUE inside the value range
specified by the MIN and MAX parameters:

SCL

Description

Use the
standard SCL
math
expressions to
create the
equation.

The CALCULATE instruction lets you create a math function that
operates on inputs (IN1, IN2, .. INn) and produces the result at OUT,
according to the equation that you define.
•

Select a data type first. All inputs and the output must be the same
data type.

•

To add another input, click the icon at the last input.

Data types for the parameters

Parameter

Data type1

IN1, IN2, ..INn

SInt, Int, DInt, USInt, UInt, UDInt, Real, LReal, Byte, Word, DWord

OUT

SInt, Int, DInt, USInt, UInt, UDInt, Real, LReal, Byte, Word, DWord

The IN and OUT parameters must be the same data type (with implicit conversions of the input parameters). For
example: A SINT value for an input would be converted to an INT or a REAL value if OUT is an INT or REAL

Click the calculator icon to open the dialog and define your math function. You enter your
equation as inputs (such as IN1 and IN2) and operations. When you click "OK" to save the
function, the dialog automatically creates the inputs for the CALCULATE instruction.
An example and a list of possible math operations you can include is shown at the bottom of
the editor.

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Note
You also must create an input for any constants in your function. The constant value would
then be entered in the associated input for the CALCULATE instruction.
By entering constants as inputs, you can copy the CALCULATE instruction to other locations
in your user program without having to change the function. You then can change the values
or tags of the inputs for the instruction without modifying the function.
When CALCULATE is executed and all the individual operations in the calculation complete
successfully, then the ENO = 1. Otherwise, ENO = 0.

6.3.5

Timers

The S7-1200 supports the following timers
● The TP timer generates a pulse with a preset width time.
● The TON timer sets the output (Q) to ON after a preset time delay.
● The TOF timer sets the output (Q) to ON and then resets the output to OFF after a preset
time delay.
● The TONR timer sets the output (Q) to ON after a preset time delay. The elapsed time is
accumulated over multiple timing periods until the reset (R) input is used to reset the
elapsed time.
For LAD and FBD, these instructions are available as either a box instruction or an output
coil. STEP 7 also provides the following timer coils for LAD and FBD:
● The PT (preset timer) coil loads a new preset time value in the specified timer.
● The RT (reset timer) coil resets the specified timer.
The number of timers that you can use in your user program is limited only by the amount of
memory in the CPU. Each timer uses 16 bytes of memory.
Each timer uses a structure stored in a data block to maintain timer data. For SCL, you must
first create the DB for the individual timer instruction before you can reference it. For LAD
and FBD, STEP 7 automatically creates the DB when you insert the instruction.

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When you create the DB, you can also use a multi-instance DB. Because the timer data is
contained in a single DB and does not require a separate DB for each timer, the processing
time for handling the timers is reduced. There is no interaction between the timer data
structures in the shared multi-instance DB.
Table 6- 9
LAD / FBD

Table 6- 10
LAD / FBD

TP (Pulse timer)
SCL

"timer_db".TP(
IN:=_bool_in_,
PT:=_undef_in_,
Q=>_bool_out_,
ET=>_undef_out_);

Timing diagram

TON (ON-delay timer)
SCL

"timer_db".TON(
IN:=_bool_in_,
PT:=_undef_in_,
Q=>_bool_out_,
ET=>_undef_out_);

Timing diagram

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Table 6- 11

TOF (OFF-delay timer)

LAD / FBD

Table 6- 12

SCL

"timer_db".TOF(
IN:=_bool_in_,
PT:=_undef_in_,
Q=>_bool_out_,
ET=>_undef_out_);

TONR (ON-delay Retentive timer)

LAD / FBD

Table 6- 13
LAD

Timing diagram

SCL

"timer_db".TONR(
IN:=_bool_in_,
R:=_bool_in_
PT:=_undef_in_,
Q=>_bool_out_,
ET=>_undef_out_);

Timing diagram

Preset timer -(PT)- and Reset timer -(RT)- coil instructions
Description
Use the Preset timer -(PT)- and Reset timer -(RT)- coil instructions with either box or coil timers. These
coil instructions can be placed in a mid-line position. The coil output power flow status is always the same
as the coil input status.
•

When the -(PT)- coil is activated, the PRESET time element of the specified IEC_Timer DB data is set
to the "PRESET_Tag" time duration.

•

When the -(RT)- coil is activated, the ELAPSED time element of the specified IEC_Timer DB data is
reset to 0.

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Table 6- 14

Data types for the parameters

Parameter

Data type

Description

Box: IN
Coil: Power flow

Bool

TP, TON, and TONR:
Box: 0=Disable timer, 1=Enable timer
Coil: No power flow=Disable timer, Power flow=Enable timer
TOF:
Box: 0=Enable timer, 1=Disable timer
Coil: No power flow=Enable timer, Power flow=Disable timer

Bool

TONR box only:
0=No reset
1= Reset elapsed time and Q bit to 0

Box: PT
Coil: "PRESET_Tag"

Time

Timer box or coil: Preset time input

Box: Q
Coil: DBdata.Q

Bool

Timer box: Q box output or Q bit in the timer DB data
Timer coil: you can only address the Q bit in the timer DB data

Box: ET
Coil: DBdata.ET

Time

Timer box: ET (elapsed time) box output or ET time value in the timer DB
data
Timer coil: you can only address the ET time value in the timer DB data.

Table 6- 15

Effect of value changes in the PT and IN parameters

Timer

Changes in the PT and IN box parameters and the corresponding coil parameters

•

Changing PT has no effect while the timer runs.

•

Changing IN has no effect while the timer runs.

•

Changing PT has no effect while the timer runs.

•

Changing IN to FALSE, while the timer runs, resets and stops the timer.

•

Changing PT has no effect while the timer runs.

•

Changing IN to TRUE, while the timer runs, resets and stops the timer.

TON
TOF
TONR

•

Changing PT has no effect while the timer runs, but has an effect when the timer resumes.

•

Changing IN to FALSE, while the timer runs, stops the timer but does not reset the timer. Changing IN
back to TRUE will cause the timer to start timing from the accumulated time value.

PT (preset time) and ET (elapsed time) values are stored in the specified IEC_TIMER DB
data as signed double integers that represent milliseconds of time. TIME data uses the T#
identifier and can be entered as a simple time unit (T#200ms or 200) and as compound time
units like T#2s_200ms.
Table 6- 16
Data type
TIME
1

Size and range of the TIME data type
Size
32 bits, stored as
DInt data

Valid number ranges1
T#-24d_20h_31m_23s_648ms to T#24d_20h_31m_23s_647ms
Stored as -2,147,483,648 ms to +2,147,483,647 ms

The negative range of the TIME data type shown above cannot be used with the timer instructions. Negative PT (preset
time) values are set to zero when the timer instruction is executed. ET (elapsed time) is always a positive value.

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Timer programming
The following consequences of timer operation should be considered when planning and
creating your user program:
● You can have multiple updates of a timer in the same scan. The timer is updated each
time the timer instruction (TP, TON, TOF, TONR) is executed and each time the
ELAPSED or Q member of the timer structure is used as a parameter of another
executed instruction. This is an advantage if you want the latest time data (essentially an
immediate read of the timer). However, if you desire to have consistent values throughout
a program scan, then place your timer instruction prior to all other instructions that need
these values, and use tags from the Q and ET outputs of the timer instruction instead of
the ELAPSED and Q members of the timer DB structure.
● You can have scans during which no update of a timer occurs. It is possible to start your
timer in a function, and then cease to call that function again for one or more scans. If no
other instructions are executed which reference the ELAPSED or Q members of the timer
structure, then the timer will not be updated. A new update will not occur until either the
timer instruction is executed again or some other instruction is executed using ELAPSED
or Q from the timer structure as a parameter.
● Although not typical, you can assign the same DB timer structure to multiple timer
instructions. In general, to avoid unexpected interaction, you should only use one timer
instruction (TP, TON, TOF, TONR) per DB timer structure.
Self-resetting timers are useful to trigger actions that need to occur periodically. Typically,
self-resetting timers are created by placing a normally-closed contact which references the
timer bit in front of the timer instruction. This timer network is typically located above one or
more dependent networks that use the timer bit to trigger actions. When the timer expires
(elapsed time reaches preset value), the timer bit is ON for one scan, allowing the dependent
network logic controlled by the timer bit to execute. Upon the next execution of the timer
network, the normally closed contact is OFF, thus resetting the timer and clearing the timer
bit. The next scan, the normally closed contact is ON, thus restarting the timer. When
creating self-resetting timers such as this, do not use the "Q" member of the timer DB
structure as the parameter for the normally-closed contact in front of the timer instruction.
Instead, use the tag connected to the "Q" output of the timer instruction for this purpose. The
reason to avoid accessing the Q member of the timer DB structure is because this causes an
update to the timer and if the timer is updated due to the normally closed contact, then the
contact will reset the timer instruction immediately. The Q output of the timer instruction will
not be ON for the one scan and the dependent networks will not execute.
The -(TP)-, -(TON)-, -(TOF)-, and -(TONR)- timer coils must be the last instruction in a
network. As shown in the timer example, a contact instruction in a subsequent network
evaluates the Q bit in a timer coil's IEC_Timer DB data. Likewise, you must address the
ELAPSED element in the IEC_timer DB data if you want to use the elapsed time value in
your program.

The pulse timer is started on a 0 to 1 transition of the Tag_Input bit value. The timer runs for
the time specified by Tag_Time time value.

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As long as the timer runs, the state of DB1.MyIEC_Timer.Q=1 and the Tag_Output value=1.
When the Tag_Time value has elapsed, then DB1.MyIEC_Timer.Q=0 and the Tag_Output
value=0.

6.3.6

Counters
You use the counter instructions to count internal program events and external process
events.
● The "count up" counter (CTU) counts up by 1 when the value of the input parameter CU
changes from 0 to 1.
● The "count down" counter (CTD) counts down by 1 when the value of input parameter CD
changes from 0 to 1.
● The "count up and down" counter (CTUD) counts up or down by 1 on the 0 to 1 transition
of the count up (CU) or count down (CD) inputs.
S7-1200 also provides high-speed counters (Page 118) (HSC) for counting events that occur
faster than the OB execution rate.
The CU, CD, and CTUD instructions use software counters whose maximum counting rate is
limited by the execution rate of the OB they are placed in.
Note
If the events to be counted occur within the execution rate of the OB, use CTU, CTD, or
CTUD counter instructions. If the events occur faster than the OB execution rate, then use
the HSC.
Each counter uses a structure stored in a data block to maintain counter data. For SCL, you
must first create the DB for the individual counter instruction before you can reference it. For
LAD and FBD, STEP 7 automatically creates the DB when you insert the instruction.
The number of counters that you can use in your user program is limited only by the amount
of memory in the CPU. Individual counters use 3 bytes (for SInt or USInt), 6 bytes (for Int or
UInt), or 12 bytes (for DInt or UDInt).

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Table 6- 17
LAD / FBD

CTU (count up) counter
SCL

"ctu_db".CTU(
CU:=_bool_in,
R:=_bool_in,
PV:=_undef_in,
Q=>_bool_out,
CV=>_undef_out);

Operation

The timing diagram shows the operation of a CTU counter with an unsigned integer count
value (where PV = 3).
● If the value of parameter CV (current count value) is greater than or equal to the value of
parameter PV (preset count value), then the counter output parameter Q = 1.
● If the value of the reset parameter R changes from 0 to 1, then CV is reset to 0.
Table 6- 18
LAD / FBD

CTD (count down) counter
SCL

"ctd_db".CTU(
CD:=_bool_in,
LOAD:=_bool_in,
PV:=_undef_in,
Q=>_bool_out,
CV=>_undef_out);

Operation

The timing diagram shows the operation of a CTD counter with an unsigned integer count
value (where PV = 3).
● If the value of parameter CV (current count value) is equal to or less than 0, the counter
output parameter Q = 1.
● If the value of parameter LOAD changes from 0 to 1, the value at parameter PV (preset
value) is loaded to the counter as the new CV.

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Table 6- 19
LAD / FBD

CTUD (count up and down) counter
SCL

"ctud_db".CTUD(
CU:=_bool_in,
CD:=_bool_in,
R:=_bool_in,
LOAD:=_bool_in,
PV:=_undef_in,
QU=>_bool_out,
QD=>_bool_out,
CV=>_undef_out);

Operation

The timing diagram shows the operation of a CTUD counter with an unsigned integer count
value (where PV = 4).
● If the value of parameter CV (current count value) is equal to or greater than the value of
parameter PV (preset value), then the counter output parameter QU = 1.
● If the value of parameter CV is less than or equal to zero, then the counter output
parameter QD = 1.
● If the value of parameter LOAD changes from 0 to 1, then the value at parameter PV is
loaded to the counter as the new CV.
● If the value of the reset parameter R changes from 0 to 1, CV is reset to 0.

6.3.7
Table 6- 20

Pulse-width modulation (PWM)
CTRL_PWM instruction

LAD / FBD

SCL
"ctrl_pwm_db"(
PWM:=_hw_pwm_in_,
enable:=_bool_in_,
busy=>_bool_out_,
status=>_word_out_);

Desciption
The CTRL_PWM instruction provides a fixed cycle
time output with a variable duty cycle. The PWM
output runs continuously after being started at the
specified frequency (cycle time). The pulse width is
varied as required to affect the desired control.

The CTRL_PWM instruction stores the parameter information in the DB. For SCL, you must
first create the DB for the instruction before you can reference it. For LAD and FBD, STEP 7
automatically creates the DB when you insert the instruction. The data block parameters are
controlled by the CTRL_PWM instruction.
The pulse width will be set to the initial value configured in device configuration when the
CPU first enters the RUN mode. You write values to the word-length output (Q) address that
was specified in device configuration ("Output addresses" / "Start address") as needed to
change the pulse width. Use an instruction (such as Move, Convert, Math, or PID) to write
the specified pulse width to the appropriate word-length output (Q). You must use the valid
range for the output value (percent, thousandths, ten-thousandths, or S7 analog format).
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①
②

Cycle time

Duty cycle can be expressed, for example, as a
percentage of the cycle time or as a relative quantity
(such as 0 to 1000 or 0 to 10000). The pulse width can
vary from 0 (no pulse, always off) to full scale (no
pulse, always on).

Pulse width time

The PWM output can be varied from 0 to full scale, providing a digital output that in many
ways is the same as an analog output. For example, the PWM output can be used to control
the speed of a motor from stop to full speed, or it can be used to control position of a valve
from closed to fully opened.

6.4

Easy to create data logs
Your control program can use the Data log instructions to store run-time data values in
persistent log files. The data log files are stored in flash memory (CPU or memory card). Log
file data is stored in standard CSV (Comma Separated Value) format. The data records are
organized as a circular log file of a pre-determined size.
The Data log instructions are used in your program to create, open, write a record, and close
the log files. You decide which program values will be logged by creating a data buffer that
defines a single log record. Your data buffer is used as temporary storage for a new log
record. New current values must be programmatically moved into the buffer during run-time.
When all of the current data values are updated, you can execute the DataLogWrite
instruction to transfer data from the buffer to a data log record.
You can open, edit, save, rename, and delete data log files from the File Browser page of
the Web Server. You must have read privileges to view the file browser and you must have
modify privileges to edit, delete, or rename data log files.
Use the DataLog instructions to programmatically store run-time process data in flash
memory of the CPU. The data records are organized as a circular log file of a predetermined size. New records are appended to the data log file. After the data log file has
stored the maximum number of records, the next record written overwrites the oldest record.
To prevent overwriting any data records, use the DataLogNewFile instruction. New data
records are stored in the new data log file, while the old data log file remains in the CPU.

Table 6- 21
LAD/FBD

DataLogWrite instruction
SCL
"DataLogWrite_DB"(
req:=_bool_in_,
done=>_bool_out_,
busy=>_bool_out_,
error=>_bool_out_,
status=>_word_out_,
ID:=_dword_inout_);

Description
DataLogWrite writes a data record into the specified data log.
The pre-existing target data log must be open.
You must programmatically load the record buffer with current
run-time data values and then execute the DataLogWrite
instruction to move new record data from the buffer to the data
log.
If there is a power failure during an incomplete DataLogWrite
operation, then the data record being transferred to the data log
could be lost.
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Table 6- 22

DataLogCreate and DataLogNewFile instructions

LAD/FBD

SCL

"DataLogCreate_DB"(
req:=_bool_in_,
records:=_udint_in_,
format:=_uint_in_,
timestamp:=_uint_in_,
done=>_bool_out_,
busy=>_bool_out_,
error=>_bool_out_,
status=>_word_out_,
name:=_string_inout_,
ID:=_dword_inout_,
header:=_variant_inout_,
data:=_variant_inout_);
"DataLogNewFile_DB"(
req:=_bool_in_,
records=:_udint_in_,
done=>_bool_out_,
busy=>_bool_out_,
error=>_bool_out_,
status=>_word_out_,
name=:_DataLog_out_,
ID:=_dword_inout_);

Description
DataLogCreate1 creates and initializes a
data log file stored in the \DataLogs
directory of the CPU. The data log file is
created with a pre-determined fixed size.

DataLogNewFile1 allows your program to
create a new data log file based upon an
existing data log file. A new data log will be
created and implicitly opened based with
the specified NAME. The header record will
be duplicated from the original data log
along with the original data log properties.
The original data log file will be implicitly
closed.

The DataLogCreate and DataLogNewFile operations extend over many program scan cycles. The actual time required
for the log file creation depends on the record structure and number of records. Before the new data log can be used for
other data log operations, your program logic must monitor the transition of the DONE bit to TRUE.

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Table 6- 23
LAD/FBD

DataLogOpen and DataLogClose instructions
SCL

"DataLogOpen_DB"(
req:=_bool_in_,
mode:=_uint_in_,
done=>_bool_out_,
busy=>_bool_out_,
error=>_bool_out_,
status=>_word_out_,
name:=_string_inout_,
ID:=_dword_inout_);
"DataLogClose_DB"(
req:=_bool_in_,
done=>_bool_out_,
busy=>_bool_out_,
error=>_bool_out_,
status=>_word_out_,
ID:=_dword_inout_);

Description
The DataLogOpen instruction opens a pre-existing data log
file. A data log must be opened before you can write new
records to the log. Data logs can be opened and closed
individually. Eight data logs can be open at the same time.

The DataLogClose instruction closes an open data log file.
DataLogWrite operations to a closed data log result in an error.
No write operations are allowed to this data log until another
DataLogOpen operation is performed.
A transition to STOP mode closes all open data log files.

6.5

Easy to monitor and test your user program

6.5.1

Watch tables and force tables
You use "watch tables" for monitoring and modifying the values of a user program being
executed by the online CPU. You can create and save different watch tables in your project
to support a variety of test environments. This allows you to reproduce tests during
commissioning or for service and maintenance purposes.
With a watch table, you can monitor and interact with the CPU as it executes the user
program. You can display or change values not only for the tags of the code blocks and data
blocks, but also for the memory areas of the CPU, including the inputs and outputs (I and Q),
peripheral inputs (I:P), bit memory (M), and data blocks (DB).
With the watch table, you can enable the physical outputs (Q:P) of a CPU in STOP mode.
For example, you can assign specific values to the outputs when testing the wiring for the
CPU.
STEP 7 also provides a force table for "forcing" a tag to a specific value. For more
information about forcing, see the section on forcing values in the CPU (Page 261) in the
"Online and Diagnostics" chapter.
Note
The force values are stored in the CPU and not in the watch table.
You cannot force an input (or "I" address). However, you can force a peripheral input. To
force a peripheral input, append a ":P" to the address (for example: "On:P").

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STEP 7 also provides the capability of tracing and recording program variables based on
trigger conditions.

6.5.2

Cross reference to show usage
The Inspector window displays cross-reference information about how a selected object is
used throughout the complete project, such as the user program, the CPU and any HMI
devices. The "Cross-reference" tab displays the instances where a selected object is being
used and the other objects using it. The Inspector window also includes blocks which are
only available online in the cross-references. To display the cross-references, select the
"Show cross-references" command. (In the Project view, find the cross references in the
"Tools" menu.)
Note
You do not have to close the editor to see the cross-reference information.
You can sort the entries in the cross-reference. The cross-reference list provides an
overview of the use of memory addresses and tags within the user program.
● When creating and changing a program, you retain an overview of the operands, tags
and block calls you have used.
● From the cross-references, you can jump directly to the point of use of operands and
tags.
● During a program test or when troubleshooting, you are notified about which memory
location is being processed by which command in which block, which tag is being used in
which screen, and which block is called by which other block.
Table 6- 24

Elements of the cross reference

Column

Description

Object

Name of the object that uses the lower-level objects or that is being used by the
lower-level objects

Quantity

Number of uses

Location

Each location of use, for example, network

Property

Special properties of referenced objects, for example, the tag names in multi-instance
declarations

Shows additional information about the object, such as whether an instance DB is
used as template or as a multiple instance

Access

Type of access, whether access to the operand is read access (R) and/or write
access (W)

Address

Address of the operand

Type

Information on the type and language used to create the object

Path

Path of object in project tree

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6.5.3

Call structure to examine the calling hierarchy
The call structure describes the call hierarchy of the block within your user program. It
provides an overview of the blocks used, calls to other blocks, the relationships between
blocks, the data requirements for each block, and the status of the blocks. You can open the
program editor and edit blocks from the call structure.
Displaying the call structure provides you with a list of the blocks used in the user program.
STEP 7 highlights the first level of the call structure and displays any blocks that are not
called by any other block in the program. The first level of the call structure displays the OBs
and any FCs, FBs, and DBs that are not called by an OB. If a code block calls another block,
the called block is shown as an indentation under the calling block. The call structure only
displays those blocks that are called by a code block.
You can selectively display only the blocks causing conflicts within the call structure. The
following conditions cause conflicts:
● Blocks that execute any calls with older or newer code time stamps
● Blocks that call a block with modified interface
● Blocks that use a tag with modified address and/or data type
● Blocks that are called neither directly nor indirectly by an OB
● Blocks that call a non-existent or missing block
You can group several block calls and data blocks as a group. You use a drop-down list to
see the links to the various call locations.
You can also perform a consistency check to show time stamp conflicts. Changing the time
stamp of a block during or after the program is generated can lead to time stamp conflicts,
which in turn cause inconsistencies among the blocks that are calling and being called.
● Most time stamp and interface conflicts can be corrected by recompiling the code blocks.
● If compilation fails to clear up inconsistencies, use the link in the "Details" column to go to
the source of the problem in the program editor. You can then manually eliminate any
inconsistencies.
● Any blocks marked in red must be recompiled.

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6.5.4

Diagnostic instructions to monitor the hardware

6.5.4.1

Reading the states of the LEDs on the CPU
The LED instruction allows your user program to determine the state of the LEDs on the
CPU. You can use this information for programming a tag for your HMI device.

Table 6- 25
LAD / FBD

6.5.4.2

LED instruction
SCL
ret_val := #LED(
laddr:=_hw_io_in_,
LED:=_uint_in_);

Description
RET_VAL returns the following LED states for the CPU
•

RUN/STOP: green or yellow

•

Error: red

•

MAINT (maintenance): yellow

•

Link: green

•

Tx/Rx (transmit/receive): yellow

Instructions for reading the diagnostic status of the devices
STEP 7 also includes instructions for reading the status information that is provided by the
hardware devices on your network.

Table 6- 26

Diagnostic instructions

LAD / FBD

SCL

ret_val := #GET_DIAG(
mode:=_uint_in_,
laddr:=_hw_any_in_,
channel:=_uint_in_,
cnt_diag=>_uint_out_,
diag:=_uint_inout_,
detail:=_variant_inout_);
ret_val := DeviceStates(
laddr:=hw_io_in_,
mode:=_uint_in_,
state:=_variant_inout_);
ret_val := ModuleStates(
laddr:=_hw_io_in_,
mode:=_uint_in,
state:=_variant_inout);

Description
The GET_DIAG instruction reads the
diagnostic information from a specified
hardware device.

The DeviceStates instruction reads the status
of PROFINET or PROFIBUS devices.

The ModuleStates instruction reads the
status of PROFINET or PROFIBUS modules.

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6.6 High-speed counter (HSC)

6.6

High-speed counter (HSC)
Use the high-speed counters (HSC) for counting events that occur faster than the OB
execution rate. The CTRL_HSC instruction controls the operation of the HSC.
Note
If the events to be counted occur within the execution rate of the OB, use CTU, CTD, or
CTUD counter instructions. If the events occur faster than the OB execution rate, then use
the HSC.
You configure the parameters for each HSC in the device configuration for the CPU:
counting mode, I/O connections, interrupt assignment, and operation as a high-speed
counter or as a device to measure pulse frequency.

Table 6- 27

CTRL_HSC instruction

LAD / FBD

SCL
"counter_name"(
hsc:=_hw_hsc_in_,
HSC:= ,
DIR:=_bool_in_,
CV:=_bool_in_,
RV:=_bool_in_,
Period:=_bool_in_,
New_DIR:=_int_in_,
New_CV:=_int_in_,
New_RV:=_dint_in_,
New_Period:=_int_in_,
Busy:=_bool_out_,
Status:=_word_out_);

Description
Each CTRL_HSC instruction uses a structure stored
in a data block to maintain counter data.
For SCL, you must first create the DB for the
individual counter instruction before you can
reference it. For LAD and FBD, STEP 7 automatically
creates the DB when you insert the instruction.

The CTRL_HSC instruction is typically placed in a hardware interrupt OB that is executed
when the counter hardware interrupt event is triggered. For example, if a CV=RV event
triggers the counter interrupt, then a hardware interrupt OB code block executes the
CTRL_HSC instruction and can change the reference value by loading a NEW_RV value.
Note
The current count value is not available in the CTRL_HSC parameters. The process image
address that stores the current count value is assigned during the hardware configuration of
the high-speed counter. You may use program logic to directly read the count value. The
value returned to your program will be a correct count for the instant in which the counter
was read. The counter will continue to count high-speed events. Therefore, the actual count
value could change before your program completes a process using an old count value.

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Some of the parameters for the HSC can be modified by your user program to provide
program control of the counting process:
● Set the counting direction to a NEW_DIR value
● Set the current count value to a NEW_CV value
● Set the reference value to a NEW_RV value
● Set the period value (for frequency measurement mode) to a NEW_PERIOD value
If the following Boolean flag values are set to 1 when the CTRL_HSC instruction is executed,
the corresponding NEW_xxx value is loaded to the counter. Multiple requests (more than
one flag is set at the same time) are processed in a single execution of the CTRL_HSC
instruction. Setting the following Boolean flag values to 0 results in no change.
● Setting DIR = 1 loads a NEW_DIR value.
● Setting CV = 1 loads a NEW_CV value.
● Setting RV = 1 loads a NEW_RV value
● Setting PERIOD = 1 loads a NEW_PERIOD value.

6.6.1

Operation of the high-speed counter
High-speed counters (HSC) can count events that occur faster than the cyclic OB execution
rate. If the events to be counted occur slower than the execution rate of the OB, you can use
CTU, CTD, or CTUD standard counter instructions. If the events occur faster than the OB
execution rate, then use the faster HSC device. The CTRL_HSC instruction allows your
program to programmatically change some of the HSC parameters.
For example: You can use the HSC as an input for an incremental shaft encoder. The shaft
encoder provides a specified number of counts per revolution and a reset pulse that occurs
once per revolution. The clock(s) and the reset pulse from the shaft encoder provide the
inputs to the HSC.
The HSC is loaded with the first of several presets, and the outputs are activated for the time
period where the current count is less than the current preset. The HSC provides an interrupt
when the current count is equal to preset, when reset occurs, and also when there is a
direction change.
As each current-count-value-equals-preset-value interrupt event occurs, a new preset is
loaded and the next state for the outputs is set. When the reset interrupt event occurs, the
first preset and the first output states are set, and the cycle is repeated.
Since the interrupts occur at a much lower rate than the counting rate of the HSC, precise
control of high-speed operations can be implemented with relatively minor impact to the scan
cycle of the CPU. The method of interrupt attachment allows each load of a new preset to be
performed in a separate interrupt routine for easy state control. Alternatively, all interrupt
events can be processed in a single interrupt routine.

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HSC input channel selection
Use the following table and ensure that the CPU and SB input channels that you connect
can support the maximum pulse rates in your process signals.
Note
CPU and SB input channels (V4 or later firmware) have configurable input filter times
Earlier firmware versions had fixed HSC input channels and fixed filter times that could not
be changed.
V4 or later versions allow you to assign input channels and filter times. The default input filter
setting of 6.4 ms may be too slow for your process signals. The filter times for the HSC
inputs must be optimized for your HSC application. See "Configuring digital input filter times"
for details.

Table 6- 28

CPU input: maximum frequency

CPU

CPU Input channel

1 or 2 phase mode

A/B Quadrature phase
mode

1211C

Ia.0 to Ia.5

100 kHz

80 kHz

1212C

Ia.0 to Ia.5

100 kHz

80 kHz

Ia.6, Ia.7

30 kHz

20 kHz

Ia.0 to Ia.5

100kHz

80kHz

Ia.6 to Ib.5

30 kHz

20 kHz

Ia.0 to Ia.5

100 kHz

80 kHz

1214C and 1215C
1217C

Ia.6 to Ib.1

30 kHz

20 kHz

Ib.2 to Ib.5

1 MHz

(.2+, .2- to .5+, .5-)

Table 6- 29

SB signal board input: maximum frequency (optional board)

SB signal board

SB input channel

1 or 2 phase mode

A/B Quadrature phase
mode

SB 1221, 200 kHz

Ie.0 to Ie.3

200kHz

160 kHz

SB 1223, 200 kHz

Ie.0, Ie.1

200kHz

160 kHz

SB 1223

Ie.0, Ie.1

30 kHz

20 kHz

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Selecting the functionality for the HSC
All HSCs function the same way for the same counter mode of operation. Counter mode,
direction control, and initial direction are assigned in the CPU device configuration for HSC
function properties.
There are four basic types of HSC:
● Single-phase counter with internal direction control
● Single-phase counter with external direction control
● Two-phase counter with 2 clock inputs
● A/B phase quadrature counter
You can use each HSC type with or without a reset input. When you activate the reset input
(with some restrictions, see the following table), the current value is cleared and held clear
until you deactivate the reset input.
● Frequency function: Some HSC modes allow the HSC to be configured (Type of
counting) to report the frequency instead of a current count of pulses. Three different
frequency measuring periods are available: 0.01, 0.1, or 1.0 seconds.
The frequency measuring period determines how often the HSC calculates and reports a
new frequency value. The reported frequency is an average value determined by the total
number of counts in the last measuring period. If the frequency is rapidly changing, the
reported value will be an intermediate between the highest and lowest frequency
occurring during the measuring period. The frequency is always reported in Hertz (pulses
per second) regardless of the frequency measuring period setting.
● Counter modes and inputs: The following table shows the inputs used for the clock,
direction control, and reset functions associated with the HSC.
The same input cannot be used for two different functions, but any input not being used
by the present mode of its HSC can be used for another purpose. For example, if HSC1
is in a mode that uses two built-in inputs but does not use the third external reset input
(default assignment at I0.3), then I0.3 can be used for edge interrupts or for HSC 2.
Table 6- 30

Counting modes for HSC

Type

Input 1

Input 2

Input 3

Function

Single-phase counter with
internal direction control

Clock

Count or frequency

Reset

Count

Single-phase counter with
external direction control

Clock

Direction

Count or frequency

Reset

Count

Two-phase counter with 2
clock inputs

Clock up

Clock down

Count or frequency

Reset

Count

A/B-phase quadrature
counter

Phase A

Count or frequency

Reset1

Count

Phase B

For an encoder: Phase Z, Home

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Input addresses for the HSC
When you configure the CPU, you have the option to enable and configure the "Hardware
inputs" for each HSC.
All HSC inputs must be connected to terminals on the CPU module or optional signal board
that plugs into the front of the CPU module.
Note
As shown in the following tables, the default assignments for the optional signals for the
different HSCs overlap. For example, the optional external reset for HSC 1 uses the same
input as one of the inputs for HSC 2. For
For V4 CPUs or later, you can reassign the HSC inputs during the CPU configuration. You
do not have to use the default input assignments.
Always ensure that you have configured your HSCs so that any one input is not being used
by two HSCs.
The following tables show the HSC input default assignments for the on-board I/O of CPUs
and an optional SB. (If the SB model selected has only 2 inputs, only 4.0 and 4.1 inputs are
available.)
HSC input table definitions
● Single-phase: C is Clock input, [d] is direction input (optional), and [R] is external reset
input (optional)
(Reset is available only for "Counting" mode.)
● Two-phase: CU is Clock Up input, CD is Clock Down input, and [R] is external reset
input.(optional)
(Reset is available only for "Counting" mode.)
● AB-phase quadrature: A is the Clock A input, B is the Clock B input, and [R] is external
reset input (optional). (Reset is available only for "Counting" mode.)
Table 6- 31

CPU 1211C: HSC default address assignments

HSC
counter mode

CPU on-board input
(default 0.x)
0

HSC 1

HSC 3

1-phase

[d]

[R]

[d]

[R]

2-phase

[R]

AB-phase
HSC 2

Optional SB input (default
4.x) 1

1-phase

[R]

[d]

[R]

[d]

2-phase

[R]

AB-phase

[R]

1-phase

[d]

2-phase
AB-phase
HSC4

1-phase

[d]

2-phase

CD
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HSC
counter mode

CPU on-board input
(default 0.x)
0

Optional SB input (default
4.x) 1

1-phase

[d]

[R]

2-phase

[R]

AB-phase
HSC 5

AB-phase
HSC 6

1-phase

[R]

[d]

2-phase

[R]

AB-phase

[R]

An SB with only 2 digital inputs provides only the 4.0 and 4.1 inputs.

Table 6- 32

CPU 1212C: HSC default address assignments

HSC counter mode

CPU on-board input
(default 0.x)
0

HSC 1

HSC 3

HSC 5

[d]

[R]

[d]

[R]

1-phase

[R]

[d]

[R]

[d]

2-phase

[R]

AB-phase

[R]

1-phase

[d]

[R]

2-phase

[R]

[d]

[R]

[d]

[R]

1-phase

[d]

[R]

2-phase

[R]

1-phase

[R]

[d]

2-phase

[R]

AB-phase

[R]

AB-phase
HSC 6

2-phase

AB-phase
HSC 4

Optional
SB input
(default 4.x) 1

1-phase
AB-phase

HSC 2

1-phase

[R]

[d]

2-phase

[R]

AB-phase

[R]

An SB with only 2 digital inputs provides only the 4.0 and 4.1 inputs.

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Table 6- 33

CPU 1214C, CPU 1215C, and CPU1217C:
HSC default address assignments
(on-board inputs only, see next table for optional SB addresses)

HSC counter mode

HSC 1

Digital input byte 0
(default: 0.x)
0

[d]

[R]

CU CD

[R]

1-phase
2-phase
AB-phase

HSC 2

HSC 3

[R]

2-phase

[R]

AB-phase

[R]

2-phase
AB-phase
HSC 4

HSC 5

1-phase

Digital input byte 1
(default: 1.x)
4

[d]

[R]

CU CD

[R]

[d]

[R]

CU CD

[R]

C
A

1-phase

[R]

2-phase

[R]

AB-phase

[R]

C
A

CU CD

[R]

Optional SB in CPUs in above table: HSC default address assignments
Optional SB inputs (default: 4.x) 1
0

1-phase

[d]

[R]

2-phase

[R]

1-phase

[R]

[d]

2-phase

[R]

AB-phase

1-phase

[d]

[R]

2-phase

[R]

AB-phase

[R]

[d]

CU CD

1-phase

AB-phase

HSC 6

[d]

[R]

1-phase

HSC

HSC 5

AB-phase

HSC 2

[d]

2-phase

HSC 1

CU CD

AB-phase

Table 6- 34

[R]

2-phase
HSC 6

1-phase

[R]

[d]

2-phase

[R]

AB-phase

[R]

An SB with only 2 digital inputs provides only the 4.0 and 4.1 inputs.

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6.6 High-speed counter (HSC)

Note
The digital I/O points used by high-speed counter devices are assigned during CPU device
configuration. When digital I/O point addresses are assigned to HSC devices, the values of
the assigned I/O point addresses cannot be modified by the force function in a watch table.

6.6.2

Configuration of the HSC
You may configure up to 6 high-speed counters. Edit
the CPU device configuration and assign the HSC
properties of each individual HSC.
Enable an HSC by selecting the "Enable" option for
that HSC
Use the CTRL_HSC instruction in your user program to
control the operation of the HSC.
.

WARNING
Risks with changes to filter time setting for digital input channels
If the filter time for a digital input channel is changed from a previous setting, a new "0"
level input value might need to be presented for up to 20.0 ms accumulated duration before
the filter becomes fully responsive to new inputs. During this time, short "0" pulse events of
duration less than 20.0 ms may not be detected or counted.
This changing of filter times can result in unexpected machine or process operation, which
can cause death or serious injury to personnel, and/or damage to equipment.
To ensure that a new filter time goes immediately into effect, power cycle the CPU.
After enabling the HSC, configure the other parameters, such as counter function, initial
values, reset options and interrupt events.

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6.6 High-speed counter (HSC)

For additional information about configuring the HSC, refer to the section on configuring the
CPU (Page 76).

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For a direct connection between the
programming device and a CPU:
• The project must include the CPU.
• The programming device is not part of the
project, but must be running STEP 7.
For a direct connection between an HMI
panel and a CPU, the project must include
both the CPU and the HMI.

For a direct connection between two CPUs:
• The project must include both CPUs.
• You must configure a network connection
between the two CPUs.
The S7-1200 CPU is a PROFINET IO controller and communicates with STEP 7 on a
programming device, with HMI devices, and with other CPUs or non-Siemens devices. An
Ethernet switch is not required for a direct connection between a programming device or HMI
and a CPU. An Ethernet switch is required for a network with more than two CPUs or HMI
devices.
By adding a PROFIBUS CM, your CPU can also function as either a master or a slave on a
PROFIBUS network.
Other communication interfaces (CM, CP or CB) support a variety of protocols, such as
Point-to-Point (PTP), Modbus, USS, and GPRS (modem).

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7.1 Creating a network connection

7.1

Creating a network connection
Use the "Network view" of Device configuration to create the network connections between
the devices in your project. After creating the network connection, use the "Properties" tab of
the inspector window to configure the parameters of the network.
Table 7- 1

Creating a network connection

Action

Result

Select "Network view" to display the
devices to be connected.

Select the port on one device and
drag the connection to the port on
the second device.

Release the mouse button to create
the network connection.

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7.2 Communication options

7.2

Communication options
The S7-1200 offers several types of communication between CPUs and programming
devices, HMIs, and other CPUs.
WARNING
If an attacker can physically access your networks, the attacker can possibly read and write
data.
The TIA Portal, the CPU, and HMIs (except HMIs using GET/PUT) use secure
communication that protects against replay and "man-in-the-middle" attacks. Once
communication is enabled, the exchange of signed messages takes place in clear text
which allows an attacker to read data, but protects against unauthorized writing of data.
The TIA Portal, not the communication process, encrypts the data of know-how protected
blocks.
All other forms of communication (I/O exchange through PROFIBUS, PROFINET, AS-i, or
other I/O bus, GET/PUT, T-Block, and communication modules (CM)) have no security
features. You must protect these forms of communication by limiting physical access. If an
attacker can physically access your networks utilizing these forms of communication, the
attacker can possibly read and write data.
For security information and recommendations, please see our "Operational Guidelines for
Industrial Security" on the Siemens Service and Support site.

PROFINET
PROFINET is used for exchanging data through the user program with other
communications partners through Ethernet:
● PROFINET supports 16 IO devices with a maximum of 256 submodules. PROFIBUS
allows 3 independent PROFIBUS DP Masters, supporting 32 slaves per DP master, with
a maximum of 512 modules per DP master.
● S7 communication
● User Datagram Protocol (UDP) protocol
● ISO on TCP (RFC 1006)
● Transport Control Protocol (TCP)

PROFINET RT IO controller
As an IO controller using PROFINET RT, the CPU communicates with up to 16 PN devices
on the local PN network or through a PN/PN coupler (link). Refer to PROFIBUS and
PROFINET International, PI (www.us.profinet.com) for more information.

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7.2 Communication options

PROFIBUS
PROFIBUS is used for exchanging data through the user program with other
communications partners through the PROFIBUS network:
● With CM 1242-5, the CPU operates as a PROFIBUS DP slave.
● With CM 1243-5, the CPU operates as a PROFIBUS DP master class1.
● PROFIBUS DP Slaves, PROFIBUS DP Masters, and AS-i (the 3 left-side communication
modules) and PROFINET are separate communications networks that do not limit each
other.

AS-i
The S7-1200 CM 1243-2 AS-i Master allows the attachment of an AS-i network to an S71200 CPU.

CPU-to-CPU S7 communication
You can create a communication connection to a partner station and use the GET and PUT
instructions to communicate with S7 CPUs.

Teleservice communication
In TeleService via GPRS, an engineering station on which STEP 7 is installed communicates
via the GSM network and the Internet with a SIMATIC S7-1200 station with a CP 1242-7.
The connection runs via a telecontrol server that serves as an intermediary and is connected
to the Internet.

IO-Link
The S7-1200 SM 1278 4xIO-Link Master enables IO-Link devices to connect to an S7 1200
CPU.

See also
Siemens service and support site
(http://www.industry.siemens.com/topics/global/en/industrialsecurity/Documents/operational_guidelines_industrial_security_en.pdf)

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7.3 Number of asynchronous communication connections

7.3

Number of asynchronous communication connections
The CPU supports the following maximum number of simultaneous, asynchronous
communication connections for PROFINET and PROFIBUS:
● 8 connections for Open User Communications (active or passive): TSEND_C, TRCV_C,
TCON, TDISCON, TSEND, and TRCV.
● 3 CPU-to-CPU S7 connections for server GET/PUT data
● 8 CPU-to-CPU S7 connections for client GET/PUT data
Note
S7-1200, S7-300, and S7-400 CPUs use the GET and PUT instructions for CPU-to-CPU
S7 communication. An S7-200 CPU uses ETHx_XFER instructions for CPU-to-CPU
S7 communication.
● HMI connections: You can configure the number of HMI connections required for your
application through the TIA Portal.
● PG connections: The CPU provides connections to support 1 programming device (PG).
● Web server (HTTP) connections: The CPU provides connections for the Web server.
Note
The Open User Communications, S7 connection, HMI, programming device, and Web server
(HTTP) communication connections may utilize multiple connection resources based upon
the features currently being used.

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7.4 PROFINET and PROFIBUS instructions

7.4

PROFINET and PROFIBUS instructions

PROFINET instructions
The TSEND_C and TRCV_C instructions make PROFINET communications simpler by
combining the functionality of the TCON and TDISCON instructions with the TSEND or
TRCV instruction.
● TSEND_C establishes a TCP or ISO on TCP communication connection to a partner
station, sends data, and can terminate the connection. After the connection is set up and
established, it is automatically maintained and monitored by the CPU. TSEND_C
combines the functions of the TCON, TDISCON and TSEND instructions into one
instruction.
● TRCV_C establishes a TCP or ISO-on-TCP communication connection to a partner CPU,
receives data, and can terminate the connection. After the connection is set up and
established, it is automatically maintained and monitored by the CPU. The TRCV_C
instruction combines the functions of the TCON, TDISCON, and TRCV instructions into
one instruction.
The TCON, TDISCON, TSEND and TRCV instructions are also supported.
Use the TUSEND and the TURCV instructions to transmit or receive data via UDP. TUSEND
and TURCV (as well as TSEND, TRCV, TCON, TDISCON) function asynchronously, which
means that the processing of the job extends over several instruction calls.
Use the IP_CONF instruction to change the IP configuration parameters from your user
program. IP_CONF works asynchronously. The execution extends over multiple calls.

PROFIBUS instructions
The DPNRM_DG (read diagnostics) instruction reads the current diagnostic data of a DP
slave in the format specified by EN 50 170 Volume 2, PROFIBUS.

Distributed I/O instructions for PROFINET, PROFIBUS and AS-i
You can use the following instructions with PROFINET, PROFIBUS, and GPRS.
● Use the RDREC (read record) and WRREC (write record) instructions to transfer a
specified data record between a component, such as a module in a central rack or a
distributed component (PROFIBUS DP or PROFINET IO).
● Use the RALRM (read alarm) instruction to read an interrupt and its information from a
DP slave or PROFINET IO device component. The information in the output parameters
contains the start information of the called OB as well as information of the interrupt
source.
● Use the DPRD_DAT (read consistent data) and DPWR_DAT (write consistent data)
instructions to transfer consistent data areas greater than 64 bytes from or to a DP
standard slave.
● For PROFIBUS only, use the DPNRM_DG instruction to read the current diagnostic data
of a DP slave in the format specified by EN 50 170 Volume 2, PROFIBUS.

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7.5 PROFINET

7.5

PROFINET

7.5.1

Open user communication
The integrated PROFINET port of the CPU supports multiple communications standards
over an Ethernet network:
● Transport Control Protocol (TCP)
● ISO on TCP (RFC 1006)
● User Datagram Protocol (UDP)

Table 7- 2

Protocols and communication instructions for each

Protocol

Usage examples

Entering data in the
receive area

Communication
instructions

Addressing type

TCP

CPU-to-CPU
communication

Ad hoc mode

Only TRCV_C and
TRCV

Transport of frames

Data reception with
specified length

TSEND_C, TRCV_C,
TCON, TDISCON,
TSEND, and TRCV

Assigns port numbers to
the Local (active) and
Partner (passive)
devices

CPU-to-CPU
communication

Ad hoc mode

Only TRCV_C and
TRCV

Message
fragmentation and reassembly

Protocol-controlled

TSEND_C, TRCV_C,
TCON, TDISCON,
TSEND, and TRCV

CPU-to-CPU
communication

User Datagram Protocol

TUSEND and TURCV

Assigns port numbers to
the Local (active) and
Partner (passive)
devices, but is not a
dedicated connection

Data transmission and
reception with specified
length

GET and PUT

Assigns TSAPs to the
Local (active) and
Partner (passive)
devices

Data transmission and
reception with specified
length

Built-in

ISO on TCP

UDP

User program
communications
S7 communication

CPU-to-CPU
communication
Read/write data
from/to a CPU

PROFINET RT

CPU-to-PROFINET
IO device
communication

Assigns TSAPs to the
Local (active) and
Partner (passive)
devices

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7.5.1.1

Ad hoc mode
Typically, TCP and ISO-on-TCP receive data packets of a specified length, ranging from 1 to
8192 bytes. However, the TRCV_C and TRCV communication instructions also provide an
"ad hoc" communications mode that can receive data packets of a variable length from 1 to
1472 bytes.
Note
If you store the data in an "optimized" DB (symbolic only), you can receive data only in
arrays of Byte, Char, USInt, and SInt data types.
To configure the TRCV_C or TRCV instruction for ad hoc mode, set the ADHOC instruction
input parameter.
If you do not call the TRCV_C or TRCV instruction in ad hoc mode frequently, you could
receive more than one packet in one call. For example: If you were to receive five 100-byte
packets with one call, TCP would deliver these five packets as one 500-byte packet, while
ISO-on-TCP would restructure the packets into five 100-byte packets.

7.5.1.2

Connection IDs for the Open user communication instructions
When you insert the TSEND_C, TRCV_C or TCON PROFINET instructions into your user
program, STEP 7 creates an instance DB to configure the communications channel (or
connection) between the devices. Use the "Properties" of the instruction to configure the
parameters for the connection. Among the parameters is the connection ID for that
connection.
● The connection ID must be unique for the CPU. Each connection that you create must
have a different DB and connection ID.
● Both the local CPU and the partner CPU can use the same connection ID number for the
same connection, but the connection ID numbers are not required to match. The
connection ID number is relevant only for the PROFINET instructions within the user
program of the individual CPU.
● You can use any number for the connection ID of the CPU. However, configuring the
connection IDs sequentially from "1" provides an easy method for tracking the number of
connections in use for a specific CPU.
Note
Each TSEND_C, TRCV_C or TCON instruction in your user program creates a new
connection. It is important to use the correct connection ID for each connection.

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The following example shows the communication between two CPUs that utilize 2 separate
connections for sending and receiving the data.
● The TSEND_C instruction in CPU_1 links to the TRCV_C in CPU_2 over the first
connection ("connection ID 1" on both CPU_1 and CPU_2).
● The TRCV_C instruction in CPU_1 links to the TSEND_C in CPU_2 over the second
connection ("connection ID 2" on both CPU_1 and CPU_2).

① TSEND_C on CPU_1 creates a

connection and assigns a connection
ID to that connection (connection ID 1
for CPU_1).

② TRCV_C on CPU_2 creates the

connection for CPU_2 and assigns the
connection ID (connection ID 1 for
CPU_2).

③ TRCV_C on CPU_1 creates a second
connection for CPU_1 and assigns a
different connection ID for that
connection (connection ID 2 for
CPU_1).

④ TSEND_C on CPU_2 creates a

second connection and assigns a
different connection ID for that
connection (connection ID 2 for
CPU_2).

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7.5 PROFINET
The following example shows the communication between two CPUs that utilize 1
connection for both sending and receiving the data.
● Each CPU uses a TCON instruction to configure the connection between the two CPUs.
● The TSEND instruction in CPU_1 links to the TRCV instruction in CPU_2 by using the
connection ID ("connection ID 1") that was configured by the TCON instruction in CPU_1.
The TRCV instruction in CPU_2 links to the TSEND instruction in CPU_1 by using the
connection ID ("connection ID 1") that was configured by the TCON instruction in CPU_2.
● The TSEND instruction in CPU_2 links to the TRCV instruction in CPU_1 by using the
connection ID ("connection ID 1") that was configured by the TCON instruction in CPU_2.
The TRCV instruction in CPU_1 links to the TSEND instruction in CPU_2 by using the
connection ID ("connection ID 1") that was configured by the TCON instruction in CPU_1.

① TCON on CPU_1 creates a

connection and assigns a connection
ID for that connection on CPU_1
(ID=1).

② TCON on CPU_2 creates a

connection and assigns a connection
ID for that connection on CPU_2
(ID=1).

③ TSEND and TRCV on CPU_1 use the
connection ID created by the TCON
on CPU_1 (ID=1).

TSEND and TRCV on CPU_2 use the
connection ID created by the TCON
on CPU_2 (ID=1).

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7.5 PROFINET
As shown in the following example, you can also use individual TSEND and TRCV
instruction to communication over a connection created by a TSEND_C or TRCV_C
instruction. The TSEND and TRCV instructions do not themselves create a new connection,
so must use the DB and connection ID that was created by a TSEND_C, TRCV_C or TCON
instruction.

① TSEND_C on CPU_1 creates a

connection and assigns a connection
ID to that connection (ID=1).

② TRCV_C on CPU_2 creates a

connection and assigns the
connection ID to that connection on
CPU_2 (ID=1).

③ TSEND and TRCV on CPU_1 use the
connection ID created by the
TSEND_C on CPU_1 (ID=1).

TSEND and TRCV on CPU_2 use the
connection ID created by the TRCV_C
on CPU_2 (ID=1).

7.5.1.3

Parameters for the PROFINET connection
The TSEND_C, TRCV_C and TCON instructions require that connection-related parameters
be specified in order to connect to the partner device. These parameters are assigned by the
TCON_Param structure for the TCP, ISO-on-TCP, and UDP protocols. Typically, you use the
"Configuration" tab of the "Properties" of the instruction to specify these parameters. If the
"Configuration" tab is not accessible, then you must specify the TCON_Param structure
programmatically.

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TCON_Param
Table 7- 3

Structure of the connection description (TCON_Param)

Byte

Parameter and data type

0…1

block_length

UInt

Description
Length: 64 bytes (fixed)

2…3

CONN_OUC
(Word)

Reference to this connection: Range of values: 1 (default) to 4095.
Specify the value of this parameter for the TSEND_C, TRCV_C or
TCON instruction under ID.

connection_type

USInt

Connection type:
•

active_est

Bool

17: TCP (default)

•

18: ISO-on-TCP

•

19: UDP

ID for the type of connection:
•

•

TCP and ISO-on-TCP:
–

FALSE: Passive connection

–

TRUE: Active connection (default)

UDP: FALSE

local_device_id

USInt

ID for the local PROFINET or Industrial Ethernet interface:
1 (default)

local_tsap_id_len

USInt

Length of parameter local_tsap_id used, in bytes; possible values:
•

TCP: 0 (active, default) or 2 (passive)

•

ISO-on-TCP: 2 to 16

•

UDP: 2

rem_subnet_id_len

USInt

This parameter is not used.

rem_staddr_len

USInt

Length of address of partner end point, in bytes:

rem_tsap_id_len

next_staddr_len

USInt

•

0: unspecified (parameter rem_staddr is irrelevant)

•

4 (default): Valid IP address in parameter rem_staddr (only for
TCP and ISO-on-TCP)

Length of parameter rem_tsap_id used, in bytes; possible values:
•

TCP: 0 (passive) or 2 (active, default)

•

ISO-on-TCP: 2 to 16

•

UDP: 0

This parameter is not used.

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Byte

Parameter and data type

12 … 27

local_tsap_id

Description
Array [1..16] of
Byte

Local address component of connection:
•

•

TCP and ISO-on-TCP: local port no. (possible values: 1 to
49151; recommended values: 2000...5000):
–

local_tsap_id[1] = high byte of port number in hexadecimal
notation;

–

local_tsap_id[2] = low byte of port number in hexadecimal
notation;

–

local_tsap_id[3-16] = irrelevant

ISO-on-TCP: local TSAP-ID:
–

local_tsap_id[1] = B#16#E0;

–

local_tsap_id[2] = rack and slot of local end points (bits 0 to
4: slot number, bits 5 to 7: rack number);

–

local_tsap_id[3-16] = TSAP extension, optional

• UDP: This parameter is not used.
Note: Make sure that every value of local_tsap_id is unique within
the CPU.
28 … 33

rem_subnet_id

Array [1..6] of
USInt

This parameter is not used.

34 … 39

rem_staddr

Array [1..6] of
USInt

TCP and ISO-on-TCP only: IP address of the partner end point.
(Not relevant for passive connections.) For example, IP address
192.168.002.003 is stored in the following elements of the array:
rem_staddr[1] = 192
rem_staddr[2] = 168
rem_staddr[3] = 002
rem_staddr[4] = 003
rem_staddr[5-6]= irrelevant

40 … 55

rem_tsap_id

Array [1..16] of
Byte

Partner address component of connection
•

•

TCP: partner port number. Range: 1 to 49151; Recommended
values: 2000 to 5000):
–

rem_tsap_id[1] = high byte of the port number in
hexadecimal notation

–

rem_tsap_id[2] = low byte of the port number in
hexadecimal notation;

–

rem_tsap_id[3-16] = irrelevant

ISO-on-TCP: partner TSAP-ID:
–

rem_tsap_id[1] = B#16#E0

–

rem_tsap_id[2] = rack and slot of partner end point (bits 0
to 4: Slot number, bits 5 to 7: rack number)

–

rem_tsap_id[3-16] = TSAP extension, optional

UDP: This parameter is not used.

56 … 61

next_staddr

Array [1..6] of
Byte

This parameter is not used.

62 … 63

spare

Word

Reserved: W#16#0000

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7.5 PROFINET

7.5.2

Configuring the Local/Partner connection path
After inserting a TSEND_C, TRCV_C or TCON instruction into the user program, the
inspector window displays the properties of the connection whenever you have selected any
part of the instruction. Specify the communication parameters in the "Configuration" tab of
the "Properties" for the communication instruction.

Table 7- 4

Configuring the connection path (using the properties of the instruction)

TCP, ISO-on-TCP, and UDP

Connection properties

For the TCP, ISO-on-TCP, and UDP Ethernet
protocols, use the "Properties" of the instruction
(TSEND_C, TRCV_C, or TCON) to configure the
"Local/Partner" connections.
The illustration shows the "Connection
properties" of the "Configuration tab" for an ISOon-TCP connection.

Note
When you configure the connection properties for one CPU, STEP 7 allows you either to
select a specific connection DB in the partner CPU (if one exists), or to create the connection
DB for the partner CPU. The partner CPU must already have been created for the project
and cannot be an "unspecified" CPU.
You must still insert a TSEND_C, TRCV_C or TCON instruction into the user program of the
partner CPU. When you insert the instruction, select the connection DB that was created by
the configuration.

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Table 7- 5

Configuring the connection path for S7 communication (Device configuration)

S7 communication (GET and PUT)

Connection properties

For S7 communication, use the "Devices &
networks" editor of the network to configure the
Local/Partner connections. You can click the
"Highlighted: Connection" button to access the
"Properties".
The "General" tab provides several properties:
•

"General" (shown)

•

"Local ID"

•

"Special connection properties"

•

"Address details" (shown)

Refer to "Protocols" (Page 133) in the "PROFINET" section or to "Creating an S7
connection" (Page 154) in the "S7 communication" section for more information and a list of
available communication instructions.
Table 7- 6

Parameters for the multiple CPU connection

Parameter

Definition

Address

Assigned IP addresses

General

Address
details

End point

Name assigned to the partner (receiving) CPU

Interface

Name assigned to the interfaces

Subnet

Name assigned to the subnets

Interface type

S7 communication only: Type of interface

Connection type

Type of Ethernet protocol

Connection ID

ID number

Connection data

Local and Partner CPU data storage location

Establish active
connection

Radio button to select Local or Partner CPU as the active connection

End point

S7 communication only: Name assigned to the partner (receiving) CPU

Rack/slot

S7 communication only: Rack and slot location

Connection resource

S7 communication only: Component of the TSAP used when configuring an

Port (decimal):

TCP and UPD: Partner CPU port in decimal format

S7 connection with an S7-300 or S7-400 CPU

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7.6 PROFIBUS

Parameter

Definition
TSAP 1 and Subnet ID:

ISO on TCP (RFC 1006) and S7 communication: Local and partner CPU
TSAPs in ASCII and hexadecimal formats

When configuring a connection with an S7-1200 CPU for ISO-on-TCP, use only ASCII characters in the TSAP extension
for the passive communication partners.

Transport Service Access Points (TSAPs)
Using TSAPs, ISO on TCP protocol and S7 communication allows multiple connections to a
single IP address (up to 64K connections). TSAPs uniquely identify these communication
end point connections to an IP address.
In the "Address Details" section of the Connection Parameters dialog, you define the TSAPs
to be used. The TSAP of a connection in the CPU is entered in the "Local TSAP" field. The
TSAP assigned for the connection in your partner CPU is entered under the "Partner TSAP"
field.

Port Numbers
With TCP and UDP protocols, the connection parameter configuration of the Local (active)
connection CPU must specify the remote IP address and port number of the Partner
(passive) connection CPU.
In the "Address Details" section of the Connection Parameters dialog, you define the ports to
be used. The port of a connection in the CPU is entered in the "Local Port" field. The port
assigned for the connection in your partner CPU is entered under the "Partner Port" field.

7.6

PROFIBUS
A PROFIBUS system uses a bus master to poll slave devices distributed in a multi-drop
fashion on an RS485 serial bus. A PROFIBUS slave is any peripheral device (I/O
transducer, valve, motor drive, or other measuring device) which processes information and
sends its output to the master. The slave forms a passive station on the network since it
does not have bus access rights, and can only acknowledge received messages, or send
response messages to the master upon request. All PROFIBUS slaves have the same
priority, and all network communication originates from the master.
A PROFIBUS master forms an "active station" on the network. PROFIBUS DP defines two
classes of masters. A class 1 master (normally a central programmable controller (PLC) or a
PC running special software) handles the normal communication or exchange of data with
the slaves assigned to it. A class 2 master (usually a configuration device, such as a laptop
or programming console used for commissioning, maintenance, or diagnostics purposes) is
a special device primarily used for commissioning slaves and for diagnostic purposes.

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The S7-1200 is connected to a PROFIBUS network as a DP slave with the CM 1242-5
communication module. The CM 1242-5 (DP slave) module can be the communications
partner of DP V0/V1 masters. If you want to configure the module in a third-party system,
there is a GSD file available for the CM 1242-5 (DP slave) on the CD that ships with the
module and on Siemens Automation Customer Support
(http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objid=6G
K72425DX300XE0&caller=view) pages on the Internet.
In the figure below, the S7-1200 is a DP slave to an S7-300 controller:

The S7-1200 is connected to a PROFIBUS network as a DP master with the CM 1243-5
communication module. The CM 1243-5 (DP master) module can be the communications
partner of DP V0/V1 slaves. In the figure below, the S7-1200 is a master controlling an
ET200S DP slave:

If a CM 1242-5 and a CM 1243-5 are installed together, an S7-1200 can perform as both a
slave of a higher-level DP master system and a master of a lower-level DP slave system,
simultaneously:

For V4.0, you can configure a maximum of three PROFIBUS CMs per station, in which there
can be any combination of DP master or DP slave CMs. DP masters in a V3.0 or greater
CPU firmware implementation can each control a maximum of 32 slaves.
The configuration data of the PROFIBUS CMs is stored on the local CPU. This allows simple
replacement of these communications modules when necessary.

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7.6 PROFIBUS

7.6.1

Communications services of the PROFIBUS CMs
The PROFIBUS CMs use the PROFIBUS DP-V1 protocol.

Types of communication with DP-V1
The following types of communication are available with DP-V1:
● Cyclic communication (CM 1242-5 and CM 1243-5)
Both PROFIBUS modules support cyclic communication for the transfer of process data
between DP slave and DP master.
Cyclic communication is handled by the operating system of the CPU. No software blocks
are required for this. The I/O data is read or written directly from/to the process image of
the CPU.
● Acyclic communication (CM 1243-5 only)
The DP master module also supports acyclic communication using software blocks:
– The "RALRM" instruction is available for interrupt handling.
– The "RDREC" and "WRREC" instructions are available for transferring configuration
and diagnostics data.
Functions not supported by the CM 1243-5: SYNC/FREEZE and Get_Master_Diag

Other communications services of the CM 1243-5
The CM 1243-5 DP master module supports the following additional communications
services:
● S7 communication
– PUT/GET services
The DP master functions as a client and server for queries from other S7 controllers or
PCs via PROFIBUS.
– PG/OP communication
The PG functions allow the downloading of configuration data and user programs from
a PG and the transfer of diagnostics data to a PG.
Possible communications partners for OP communication are HMI panels, SIMATIC
panel PCs with WinCC flexible or SCADA systems that support S7 communication.

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7.6 PROFIBUS

7.6.2

Reference to the PROFIBUS CM user manuals

Further information
You can find detailed information on the PROFIBUS CMs in the manuals for the devices.
You can find these on the Internet in the pages of Siemens Industrial Automation Customer
Support under the following entry IDs:
● CM 1242-5 (http://support.automation.siemens.com/WW/view/en/49852105)
● CM 1243-5 (http://support.automation.siemens.com/WW/view/en/49851842)

7.6.3

Adding the CM 1243-5 (DP master) module and a DP slave
In the "Devices and networks" portal, use the hardware catalog to add PROFIBUS modules
to the CPU. These modules are connected to the left side of the CPU. To insert a module
into the hardware configuration, select the module in the hardware catalog and either
double-click or drag the module to the highlighted slot.

Table 7- 7
Module

Adding a PROFIBUS CM 1243-5 (DP master) module to the device configuration
Select the module

Insert the module

Result

CM 1243-5
(DP
master)

Use the hardware catalog to add DP slaves as well. For example, to add an ET200 S DP
slave, in the Hardware Catalog, expand the following containers:
● Distributed I/O
● ET200 S
● Interface modules
● PROFIBUS

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7.6 PROFIBUS
Next, select "6ES7 151-1BA02-0AB0" (IM151-1 HF) from the list of part numbers, and add
the ET200 S DP slave as shown in the figure below.
Table 7- 8

Adding an ET200 S DP slave to the device configuration
Insert the DP slave

7.6.4

Result

Assigning PROFIBUS addresses to the CM 1243-5 module and DP slave

Configuring the PROFIBUS interface
After you configure logical network connections between two PROFIBUS devices, you can
configure parameters for the PROFIBUS interfaces. To do so, click the purple PROFIBUS
box on the CM 1243-5 module, and the "Properties" tab in the inspector window displays the
PROFIBUS interface. The DP slave PROFIBUS interface is configured in the same manner.
Table 7- 9

Configuring the CM 1243-5 (DP master) module and ET200 S DP slave PROFIBUS
interfaces

CM 1243-5 (DP master) module

ET200 S DP slave

① PROFIBUS port

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7.6 PROFIBUS

Assigning the PROFIBUS address
In a PROFIBUS network, each device is assigned a PROFIBUS address. This address can
range from 0 through 127, with the following exceptions:
● Address 0: Reserved for network configuration and/or programming tools attached to the
bus
● Address 1: Reserved by Siemens for the first master
● Address 126: Reserved for devices from the factory that do not have a switch setting and
must be re-addressed through the network
● Address 127: Reserved for broadcast messages to all devices on the network and may
not be assigned to operational devices
Thus, the addresses that may be used for PROFIBUS operational devices are 2 through
125.
In the Properties window, select the "PROFIBUS address" configuration entry. STEP 7
displays the PROFIBUS address configuration dialog, which is used to assign the
PROFIBUS address of the device.

Table 7- 10

Parameters for the PROFIBUS address

Parameter
Subnet

Parameters

Description
Name of the Subnet to which the device is connected. Click the "Add new subnet" button to create a
new subnet. "Not connected" is the default. Two connection types are possible:
•

The "Not connected" default provides a local connection.

•

A subnet is required when your network has two or more devices.

Address

Assigned PROFIBUS address for the device

Highest address

The highest PROFIBUS address is based on the active stations on the
PROFIBUS (for example, DP master). Passive DP slaves independently
have PROFIBUS addresses from 1 to 125 even if the highest PROFIBUS
address is set to 15, for example. The highest PROFIBUS address is
relevant for token forwarding (forwarding of the send rights), and the token
is only forwarded to active stations. Specifying the highest PROFIBUS
address optimizes the bus.

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7.7 AS-i

Parameter

Description
Transmission rate

Transmission rate of the configured PROFIBUS network: The PROFIBUS
transmission rates range from 9.6 Kbits/sec to 12 Mbits/sec. The
transmission rate setting depends on the properties of the PROFIBUS
nodes being used. The transmission rate should not be greater than the
rate supported by the slowest node.
The transmission rate is normally set for the master on the PROFIBUS
network, with all DP slaves automatically using that same transmission rate
(auto-baud).

7.7

AS-i
The S7-1200 AS-i master CM 1243-2 allows the attachment of an AS-i network to an S71200 CPU.
The actuator/sensor interface, or AS-i, is a single master network connection system for the
lowest level in automation systems. The CM 1243-2 serves as the AS-i master for the
network. Using a single AS-i cable, sensors and actuators (AS-i slave devices) can be
connected to the CPU through the CM 1243-2. The CM 1243-2 handles all AS-i network
coordination and relays data and status information from the actuators and sensors to the
CPU through the I/O addresses assigned to the CM 1243-2. You can access binary or
analog values depending on the slave type. The AS-i slaves are the input and output
channels of the AS-i system and are only active when called by the CM 1243-2.
In the figure below, the S7-1200 is an AS-i master controlling AS-i operator panel and I/O
module digital/analog slave devices.

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7.7.1

Adding the AS-i master CM 1243-2 and AS-i slave
Use the hardware catalog to add AS-i master CM1243-2 modules to the CPU. These
modules are connected to the left side of the CPU, and a maximum of three AS-i master
CM1243-2 modules can be used. To insert a module into the hardware configuration, select
the module in the hardware catalog and either double-click or drag the module to the
highlighted slot.

Table 7- 11
Module

Adding an AS-i master CM1243-2 module to the device configuration
Select the module

Insert the module

Result

CM 1243-2
AS-i
Master

Use the hardware catalog to add AS-i slaves as well. For example, to add an "I/O module,
compact, digital, input" slave, in the Hardware Catalog, expand the following containers:
● Field devices
● AS-Interface slaves
Next, select "3RG9 001-0AA00" (AS-i SM-U, 4DI) from the list of part numbers, and add the
"I/O module, compact, digital, input" slave as shown in the figure below.
Table 7- 12

Adding an AS-i slave to the device configuration
Insert the AS-i slave

Result

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7.7.2

Assigning an AS-i address to an AS-i slave

Configuring the AS-i slave interface
To configure parameters for the AS-i interface, click the yellow AS-i box on the AS-i slave,
and the "Properties" tab in the inspector window displays the AS-i interface.

①

AS-i port

Assigning the AS-i slave address
In an AS-i network, each device is assigned an AS-i slave address. This address can range
from 0 through 31; however, address 0 is reserved only for new slave devices. The slave
addresses are 1(A or B) to 31(A or B) for a total of up to 62 slave devices.
"Standard" AS-i devices use the entire addresss, having a number address without the A or
B designation. "A/B node" AS-i devices use the A or B portion of each address, enabling
each of the 31 addresses to be used twice. The address space range is 1A to 31A plus 1B to
31B.
Any address in the range of 1 - 31 can be assigned to an AS-i slave device; in other words, it
does not matter whether the slaves begin with address 21 or whether the first slave is
actually given the address 1.

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In the example below, three AS-i devices have been addressed as "1" (a standard type
device), "2A" (an A/B node type device), and "3" (a standard type device):

①
②
③

AS-i slave address 1; Device: AS-i SM-U, 4DI; order number: 3RG9 001-0AA00
AS-i slave address 2A; Device: AS-i 8WD44, 3DO, A/B; order number: 8WD4 428-0BD
AS-i slave address 3; Device: AS-i SM-U, 2DI/2DO; order number: 3RG9 001-0AC00

Enter the AS-i slave address here:

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Table 7- 13
Parameter

Parameters for the AS-i interface
Description

Network

Name of the network to which the device is connected

Address(es)

Assigned AS-i address for the slave device in range of 1(A or B) to 31(A or B) for a total of up to 62
slave devices

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7.8 S7 communication

7.8

S7 communication

7.8.1

GET and PUT instructions
You can use the GET and PUT instructions to communicate with S7 CPUs through
PROFINET and PROFIBUS connections. This is only possible if the "Permit access with
PUT/GET communication" function is activated for the partner CPU in the "Protection"
property of the local CPU properties:
● Accessing data in a remote CPU: An S7-1200 CPU can only use absolute addresses in
the ADDR_x input field to address variables of remote CPUs (S7-200/300/400/1200).
● Accessing data in a standard DB: An S7-1200 CPU can only use absolute addresses in
the ADDR_x input field to address DB variables in a standard DB of a remote S7 CPU.
● Accessing data in an optimized DB: An S7-1200 CPU cannot access DB variables in an
optimized DB of a remote S7-1200 CPU.
● Accessing data in a local CPU: An S7-1200 CPU can use either absolute or symbolic
addresses as inputs to the RD_x or SD_x input fields of the GET or PUT instruction,
respectively.
STEP 7 automatically creates the DB when you insert the instruction.
Note
To ensure data consistency, always evaluate when the operation has been completed
(NDR = 1 for GET, or DONE = 1 for PUT) before accessing the data or initiating another
read or write operation.
Note
V4.0 CPU program GET/PUT operation is not automatically enabled
A V3.0 CPU program GET/PUT operation is automatically enabled in a V4.0 CPU.
However, a V4.0 CPU program GET/PUT operation in a V4.0 CPU is not automatically
enabled. You must go the CPU "Device configuration", inspector window "Properties"tab,
"Protection" property to enable GET/PUT access (Page 82).

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7.8.2

Creating an S7 connection

Connection mechanisms
To access remote connection partners with PUT/GET instructions, the user must also have
permission.
By default, the "Permit access with PUT/GET communication" option is not enabled. In this
case, read and write access to CPU data is only possible for communication connections
that require configuration or programming both for the local CPU and for the communication
partner. Access through BSEND/BRCV instructions is possible, for example.
Connections for which the local CPU is only a server (meaning that no
configuration/programming of the communication with the communication partner exists at
the local CPU), are therefore not possible during operation of the CPU, for example:
● PUT/GET, FETCH/WRITE or FTP access through communication modules
● PUT/GET access from other S7 CPUs
● HMI access through PUT/GET communication
If you want to allow access to CPU data from the client side, that is, you do not want to
restrict the communication services of the CPU, refer to "Access protection for the S7-1200
CPU" for more information.

Connection types
The connection type that you select creates a communication connection to a partner
station. The connection is set up, established, and automatically monitored.
In the Devices and Networks portal, use the "Network view" to create the network
connections between the devices in your project. First, click the "Connections" tab, and then
select the connection type with the dropdown, just to the right (for example, an S7
connection). Click the green (PROFINET) box on the first device, and drag a line to the
PROFINET box on the second device. Release the mouse button and your PROFINET
connection is joined.
Refer to "Creating a network connection" for more information.

Click the "Highlighted: Connection" button to access the "Properties" configuration dialog of
the communication instruction.

See also
Creating a network connection (Page 128)
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7.8.3

GET/PUT connection parameter assignment
The GET/PUT instructions connection parameter assignment is a user aid for configuring S7
CPU-CPU communication connections.
After inserting a GET or PUT block, the GET/PUT instructions connection parameter
assignment is started:

The inspector window displays the properties of the connection whenever you have selected
any part of the instruction. Specify the communication parameters in the "Configuration" tab
of the "Properties" for the communication instruction.
After inserting a GET or PUT block, the "Configuration" tab automatically appears and the
"Connection parameters" page is immediately shown. This page allows the user to configure
the necessary S7 connection and to configure the parameter "Connection ID" that is
referenced by the block parameter "ID". A "Block parameters" page allows the user to
configure additional block parameters.
Note
V4.0 CPU program GET/PUT operation is not automatically enabled
A V3.0 CPU program GET/PUT operation is automatically enabled in a V4.0 CPU.
However, a V4.0 CPU program GET/PUT operation in a V4.0 CPU is not automatically
enabled. You must go the CPU "Device configuration", inspector window "Properties"tab,
"Protection" property to enable GET/PUT access (Page 82).

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7.9 GPRS

7.9

GPRS

7.9.1

Connection to a GSM network

IP-based WAN communication via GPRS
Using the CP 1242-7 communications processor, the S7-1200 can be connected to GSM
networks. The CP 1242-7 allows WAN communication from remote stations with a control
center and inter-station communication.
Inter-station communication is possible only via a GSM network. For communication
between a remote station and a control room, the control center must have a PC with
Internet access.
The CP 1242-7 supports the following services for communication via the GSM network:
● GPRS (General Packet Radio Service)
The packet-oriented service for data transmission "GPRS" is handled via the GSM
network.
● SMS (Short Message Service)
The CP 1242-7 can receive and send SMS messages. The communications partner can
be a mobile phone or an S7-1200.
The CP 1242-7 is suitable for use in industry worldwide and supports the following frequency
bands:
● 850 MHz
● 900 MHz
● 1 800 MHz
● 1 900 MHz

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Requirements
The equipment used in the stations or the control center depends on the particular
application.
● For communication with or via a central control room, the control center requires a PC
with Internet access.
● Apart from the station equipment, a remote S7-1200 station with a CP 1242-7 must meet
the following requirements to be able to communicate via the GSM network:
– A contract with a suitable GSM network provider
If GPRS is used, the contract must allow the use of the GPRS service.
If there is to be direct communication between stations only via the GSM network, the
GSM network provider must assign a fixed IP address to the CPs. In this case,
communication between stations is not via the control center.
– The SIM card belonging to the contract
The SIM card is inserted in the CP 1242-7.
– Local availability of a GSM network in the range of the station
Below, you will find several configuration examples for stations with a CP 1242-7.

Sending messages by SMS

Figure 7-1

Sending messages by SMS from an S7-1200 station

A SIMATIC S7-1200 with a CP 1242-7 can send messages by SMS to a configured mobile
phone or a configured S7-1200 station.

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Telecontrol by a control center

Figure 7-2

Communication between S7-1200 stations and a control center

In telecontrol applications, SIMATIC S7-1200 stations with a CP 1242-7 communicate with a
control center via the GSM network and the Internet. The TELECONTROL SERVER BASIC
application is installed on the telecontrol server in the master station. This results in the
following use cases:
● Telecontrol communication between station and control center
In this use case, data from the field is sent by the stations to the telecontrol server in the
master station via the GSM network and Internet. The telecontrol server is used to control
and monitor remote stations.
● Communication between a station and a control center PC with OPC client
As in the first case, the stations communicate with the telecontrol server. Using the OPC
server of TELECONTROL SERVER BASIC, the telecontrol server exchanges data with a
master station PC. The control center PC could, for example, have WinCC and an
integrated OPC client installed on it.
● Inter-station communication via a control center
To allow inter-station communication, the telecontrol server forwards the messages of the
sending station to the receiving station.

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Direct communication between stations

Figure 7-3

Direct communication between two S7-1200 stations

In this configuration, two SIMATIC S7-1200 stations communicate directly with each other
using the CP 1242-7 via the GSM network. Each CP 1242-7 has a fixed IP address. The
relevant service of the GSM network provider must allow this.

TeleService via GPRS

Figure 7-4

TeleService via GPRS

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7.9 GPRS
In TeleService via GPRS, an engineering station on which STEP 7 is installed communicates
via the GSM network and the Internet with a SIMATIC S7-1200 station with a CP 1242-7.
The connection runs via a telecontrol server that serves as an intermediary and is connected
to the Internet.
The CP 1242-7 can be used for the following applications:

Telecontrol applications
● Sending messages by SMS
Via the CP 1242-7, the CPU of a remote S7-1200 station can receive SMS messages
from the GSM network or send messages by SMS to a configured mobile phone or an
S7-1200.
● Communication with a control center
Remote S7-1200 stations communicate via the GSM network and the Internet with a
telecontrol server in the master station. For data transfer using GPRS, the
"TELECONTROL SERVER BASIC" application is installed on the telecontrol server in the
master station. The telecontrol server communicates with a higher-level central control
system using the integrated OPC server function.
● Inter-station communication between S7-1200 stations via a GSM network
Inter-station communication between remote stations with a CP 1242-7 can be handled in
two different ways:
– Indirect communication via a master station
In this configuration, a permanent secure connection between S7-1200 stations that
communicate with each other and the telecontrol server is established in the master
station. Communication between the stations is via the telecontrol server. The
CP 1242-7 operates in "Telecontrol" mode.
– Direct communication between the stations
For direct communication between stations without the detour via the master station,
SIM cards with a fixed IP address are used that allow the stations to address each
other directly. The possible communications services and security functions (for
example VPN) depend on what is offered by the network provider. The CP 1242-7
operates in "GPRS direct" mode.

TeleService via GPRS
A TeleService connection can be established between an engineering station with STEP 7
and a remote S7-1200 station with a CP 1242-7 via the GSM network and the Internet. The
connection runs from the engineering station via a telecontrol server or a TeleService
gateway that acts as an intermediary forwarding frames and establishing the authorization.
These PCs use the functions of the "TELECONTROL SERVER BASIC" application.
You can use the TeleService connection for the following purposes:
● Downloading configuration or program data from the STEP 7 project to the station
● Querying diagnostics data on the station

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Other services and functions of the CP 1242-7
● Time-of-day synchronization of the CP via the Internet
You can set the time on the CP as follows:
– In "Telecontrol" mode, the time of day is transferred by the telecontrol server. The CP
uses this to set its time.
– In "GPRS direct" mode, the CP can request the time using SNTP.
To synchronize the CPU time, you can read out the current time from the CP using a
block.
● Interim buffering of messages to be sent if there are connection problems
● Logging the volume of data
The volumes of data transferred are logged and can be evaluated for specific purposes.

Configuration and module replacement
To configure the module, the following configuration tool is required:
STEP 7 version V11.0 SP1 or higher
For STEP 7 V11.0 SP1, you also require support package "CP 1242-7" (HSP0003001).
For process data transfer using GPRS, use the telecontrol communications instructions in
the user program of the station.
The configuration data of the CP 1242-7 is stored on the local CPU. This allows simple
replacement of the CP when necessary.
You can insert up to three modules of the CP 1242-7 type per S7-1200. This, for example,
allows redundant communications paths to be established.

Electrical connections
● Power supply of the CP 1242-7
The CP has a separate connection for the external 24 VDC power supply.
● Wireless interface for the GSM network
An extra antenna is required for GSM communication. This is connected via the SMA
socket of the CP.

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The ANT794-4MR GSM/GPRS antenna
The following antennas are available for use in GSM/GPRS networks and can be installed
both indoors and outdoors:
● Quadband antenna ANT794-4MR

Figure 7-5

ANT794-4MR GSM/GPRS antenna

Short name

Order no.

Explanation

ANT794-4MR

6NH9 860-1AA00

Quadband antenna (900, 1800/1900 MHz, UMTS);
weatherproof for indoor and outdoor areas; 5 m
connecting cable connected permanently to the
antenna; SMA connector, including installation
bracket, screws, wall plugs

● Flat antenna ANT794-3M

Figure 7-6

Flat antenna ANT794-3M

Short name

Order no.

Explanation

ANT794-3M

6NH9 870-1AA00

Flat antenna (900, 1800/1900 MHz); weatherproof
for indoor and outdoor areas; 1.2 m connecting cable
connected permanently to the antenna; SMA
connector, including adhesive pad, screws mounting
possible

The antennas must be ordered separately.

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7.10 PtP, USS, and Modbus communication protocols

7.10

PtP, USS, and Modbus communication protocols

7.10.1

Point-to-point communication
The CPU supports the following Point-to-Point communication (PtP) for character-based
serial protocols:
● PtP (Page 164)
● USS (Page 165)
● Modbus (Page 167)
PtP provides maximum freedom and flexibility, but requires extensive implementation in the
user program.
PtP enables a wide variety of possibilities:
• The ability to send information directly to an external
device such as a printer
• The ability to receive information from other devices
such as barcode readers, RFID readers, third-party
camera or vision systems, and many other types of
devices
• The ability to exchange information, sending and
receiving data, with other devices such as GPS
devices, third-party camera or vision systems, radio
modems, and many more
This type of PtP communication is serial
communication that uses standard UARTs to support a
variety of baud rates and parity options. The RS232
and RS422/485 communication modules (CM 1241)
and the RS485 communication board (CB 1241)
provide the electrical interfaces for performing the PtP
communications.

7.10.2

Using the serial communication interfaces
Two communication modules (CMs) and one communication board (CB) provide the
interface for PtP communications:
● CM 1241 RS232
● CM 1241 RS422/485
● CB 1241 RS485
You can connect up to three CMs (of any type) plus a CB for a total of four communication
interfaces. Install the CM to the left of the CPU or another CM. Install the CB on the front of
the CPU. Refer to the "Installation" chapter in the S7-1200 System Manual for detailed
instructions on module installation and removal.

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The serial communication interfaces have the following characteristics:
● Have an isolated port
● Support Point-to-Point protocols
● Are configured and programmed through the point-to-point communication processor
instructions
● Display transmit and receive activity by means of LEDs
● Display a diagnostic LED (CMs only)
● Are powered by the CPU: No external power connection is needed.
Refer to the technical specifications for communication interfaces.

LED indicators
The communication modules have three LED indicators:
● Diagnostic LED (DIAG): This LED flashes red until it is addressed by the CPU. After the
CPU powers up, it checks for CMs and addresses them. The diagnostic LED begins to
flash green. This means that the CPU has addressed the CM, but has not yet provided
the configuration to it. The CPU downloads the configuration to the configured CMs when
the program is downloaded to the CPU. After a download to the CPU, the diagnostic LED
on the communication module should be a steady green.
● Transmit LED (Tx): The transmit LED illuminates when data is being transmitted out the
communication port.
● Receive LED (Rx): This LED illuminates when data is being received by the
communication port.
The communication board provides transmit (TxD) and receive (RxD) LEDs. It has no
diagnostic LED.

7.10.3

PtP instructions
The PORT_CFG, SEND_CFG, and RCV_CFG instructions allow you to change the
configuration from your user program.
● PORT_CFG changes the port parameters such as baud rate.
● SEND_CFG changes the configuration of serial transmission parameters.
● RCV_CFG changes the configuration of serial receiver parameters in a communication
port. This instruction configures the conditions that signal the start and end of a received
message. Messages that satisfy these conditions will be received by the RCV_PTP
instruction.

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7.10 PtP, USS, and Modbus communication protocols
The dynamic configuration changes are not permanently stored in the CPU. After a power
cycle, the initial static configuration from the device configuration will be used.
The SEND_PTP, RCV_PTP, and RCV_RST instructions control the PtP communication:
● SEND_PTP transfers the specified buffer to the CM or CB. The CPU continues to execute
the user program while the module sends the data at the specified baud rate.
● RCV_PTP checks for messages that have been received in the CM or CB. If a message
is available, it will be transferred to the CPU.
● The RCV_RST resets the receive buffer.
Each CM or CB can buffer up to a maximum of 1K bytes. This buffer can be allocated across
multiple received messages.
The SGN_SET and SGN_GET are valid only for the RS232 CM. Use these instructions to
read or set the RS232 communication signals.

7.10.4

USS instructions
S7-1200 supports the USS protocol and provides instructions that are specifically designed
for communicating with drives over the RS485 port of a CM or a CB. You can control the
physical drive and the read/write drive parameters with the USS instructions. Each RS485
CM or CB supports a maximum of 16 drives.
● The USS_PORT instruction handles actual communication between the CPU and all the
drives attached to one CM or CB. Insert a different USS_PORT instruction for each CM or
CB in your application. Ensure that the user program executes the USS_PORT
instruction fast enough to prevent a communication timeout by the drive. Use the
USS_PORT instruction in a program cycle or any interrupt OB.
● The USS_DRV instruction accesses a specified drive on the USS network. The input and
output parameters of the USS_DRV instruction are the status and controls for the drive. If
there are 16 drives on the network, your program must have at least 16 USS_DRV
instructions, with one instruction for each drive.
Ensure that the CPU executes the USS_DRV instruction at the rate that is required to
control the functions of the drive. Use the USS_DRV instruction only in a program cycle
OB.
● The USS_RPM and USS_WPM instructions read and write the operating parameters of
the remote drive. These parameters control the internal operation of the drive. See the
drive manual for the definition of these parameters.
Your program can contain as many of these instructions as necessary. However, only
one read or write request can be active for any one drive at any given time. Use the
USS_RPM and USS_WPM instructions only in a program cycle OB.
An instance DB contains temporary storage and buffers for all of the drives on the USS
network connected to each CM or CB. The USS instructions for a drive use the instance DB
to share the information.

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7.10 PtP, USS, and Modbus communication protocols

Calculating the time required for communicating with the drive
Communications with the drive are asynchronous to the CPU scan. The CPU typically
completes several scans before one drive communications transaction is completed.
The USS_PORT interval is the time required for one drive transaction. The table below
shows the minimum USS_PORT interval for each communication baud rate. Calling the
USS_PORT function more frequently than the USS_PORT interval will not increase the
number of transactions. The drive timeout interval is the amount of time that might be taken
for a transaction, if communications errors caused 3 tries to complete the transaction. By
default, the USS protocol library automatically does up to 2 retries on each transaction.
Table 7- 14

Calculating the time requirements

Baud rate

Calculated minimum USS_PORT call
Interval ( milliseconds )

Drive message interval timeout per
drive ( milliseconds )

1200

790

2370

2400

405

1215

4800

212.5

638

9600

116.3

349

19200

68.2

205

38400

44.1

133

57600

36.1

109

115200

28.1

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7.10 PtP, USS, and Modbus communication protocols

7.10.5

Modbus instructions
The CPU supports Modbus communication over different networks:
● Modbus RTU (Remote Terminal Unit) is a standard network communication protocol that
uses the RS232 or RS485 electrical connection for serial data transfer between Modbus
network devices. You can add PtP (Point to Point) network ports to a CPU with a RS232
or RS485 CM or a RS485 CB.
Modbus RTU uses a master/slave network where all communications are initiated by a
single Master device and slaves can only respond to a master’s request. The master
sends a request to one slave address and only that slave address responds to the
command.
● Modbus TCP (Transmission Control Protocol) is a standard network communication
protocol that uses the PROFINET connector on the CPU for TCP/IP communication. No
additional communication hardware module is required.
Modbus TCP uses client-server connections as a Modbus communication path. Multiple
client-server connections may exist, in addition to the connection between STEP 7 and
the CPU. Mixed client and server connections are supported up to the maximum number
of connections allowed by the CPU. Each MB_SERVER connection must use a unique
instance DB and IP port number. Only 1 connection per IP port is supported. Each
MB_SERVER (with its unique instance DB and IP port) must be executed individually for
each connection.
WARNING
If an attacker can physically access your networks, the attacker can possibly read and
write data.
The TIA Portal, the CPU, and HMIs (except HMIs using GET/PUT) use secure
communication that protects against replay and "man-in-the-middle" attacks. Once
communication is enabled, the exchange of signed messages takes place in clear text
which allows an attacker to read data, but protects against unauthorized writing of data.
The TIA Portal, not the communication process, encrypts the data of know-how
protected blocks.
All other forms of communication (I/O exchange through PROFIBUS, PROFINET, AS-i,
or other I/O bus, GET/PUT, T-Block, and communication modules (CM)) have no
security features. You must protect these forms of communication by limiting physical
access. If an attacker can physically access your networks utilizing these forms of
communication, the attacker can possibly read and write data.
For security information and recommendations, please see our "Operational Guidelines
for Industrial Security" on the Service and Support site:
www.industry.siemens.com/topics/global/en/industrialsecurity/Documents/operational_guidelines_industrial_security_en.pdf
(http://www.industry.siemens.com/topics/global/en/industrialsecurity/Documents/operational_guidelines_industrial_security_en.pdf)
Note
Modbus TCP will only operate correctly with CPU firmware release V1.02 or later. An
attempt to execute the Modbus instructions on an earlier firmware version will result in an
error.

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7.10 PtP, USS, and Modbus communication protocols
Table 7- 15

Modbus instructions

Type of communication

Instruction

Modbus RTU (RS232 or RS485)

MB_COMM_LOAD: One execution of MB_COMM_LOAD is used to set up PtP port
parameters like baud rate, parity, and flow control. After the CPU port is configured
for the Modbus RTU protocol, it can only be used by either the MB_MASTER or
MB_SLAVE instructions.
MB_MASTER: The Modbus master instruction enables the CPU to act as a Modbus
RTU master device and communicate with one or more Modbus slave devices.
MB_SLAVE: The Modbus slave instruction enables the CPU to act as a Modbus RTU
slave device and communicate with a Modbus master device.

Modbus TCP (PROFINET)

MB_CLIENT: Make client-server TCP connection, send command message, receive
response, and control the disconnection from the server.
MB_SERVER: Connect to a Modbus TCP client upon request, receive Modbus
message, and send response.

The Modbus instructions do not use communication interrupt events to control the
communication process. Your program must poll the MB_MASTER / MB_SLAVE or
MB_Client / MB_Server instructions for transmit and receive complete conditions.
A Modbus TCP client (master) must control the client-server connection with the
DISCONNECT parameter. The basic Modbus client actions are shown below.
1. Initiate a connection to a particular server (slave) IP address and IP port number
2. Initiate client transmission of Modbus messages and receive the server responses
3. When required, initiate the disconnection of client and server to enable connection with a
different server.

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STEP 7 provides the following PID instructions for the S7-1200 CPU:

● The PID_Compact instruction is used to control technical processes with continuous
input- and output variables.
● The PID_3Step instruction is used to control motor-actuated devices, such as valves that
require discrete signals for open- and close actuation.
Note
Changes that you make to the PID configuration and download in RUN do not take effect
until the CPU transitions from STOP to RUN mode. Changes that you make in the "PID
parameters" dialog using the "Start value control" take effect immediately.
Both PID instructions (PID_3Step and PID_Compact) can calculate the P-, I-, and Dcomponents during startup (if configured for "pre-tuning"). You can also configure the
instruction for "fine tuning" to allow you to optimize the parameters. You do not need to
manually determine the parameters.
Note
Execute the PID instruction at constant intervals of the sampling time (preferably in a cyclic
OB).
Because the PID loop needs a certain time to respond to changes of the control value, do
not calculate the output value in every cycle. Do not execute the PID instruction in the main
program cycle OB (such as OB 1).
The sampling time of the PID algorithm represents the time between two calculations of the
output value (control value). The output value is calculated during self-tuning and rounded to
a multiple of the cycle time. All other functions of PID instruction are executed at every call.

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PID algorithm
The PID (Proportional/Integral/Derivative) controller measures the time interval between two
calls and then evaluates the results for monitoring the sampling time. A mean value of the
sampling time is generated at each mode changeover and during initial startup. This value is
used as reference for the monitoring function and is used for calculation. Monitoring includes
the current measuring time between two calls and the mean value of the defined controller
sampling time.
The output value for the PID controller consists of three components:
● P (proportional): When calculated with the "P" component, the output value is proportional
to the difference between the setpoint and the process value (input value).
● I (integral): When calculated with the "I" component, the output value increases in
proportion to the duration of the difference between the setpoint and the process value
(input value) to finally correct the difference.
● D (derivative): When calculated with the "D" component, the output value increases as a
function of the increasing rate of change of the difference between the setpoint and the
process value (input value). The output value is corrected to the setpoint as quickly as
possible.
The PID controller uses the following formula to calculate the output value for the
PID_Compact instruction.

Output value

Process value

Setpoint value

Laplace operator

Proportional gain
(P component)

Derivative delay coefficient
(D component)

Integral action time
(I component)

Proportional action weighting
(P component)

Derivative action time
(D component)

Derivative action weighting
(D component)

The PID controller uses the following formula to calculate the output value for the PID_3Step
instruction.

Output value

Process value

Setpoint value

Laplace operator

Proportional gain
(P component)

Derivative delay coefficient
(D component)

Integral action time
(I component)

Proportional action weighting
(P component)

Derivative action time
(D component)

Derivative action weighting
(D component)

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8.1 Inserting the PID instruction and technology object

8.1

Inserting the PID instruction and technology object
STEP 7 provides two instructions for PID control:
● The PID_Compact instruction and its associated technology object provide a universal
PID controller with tuning. The technology object contains all of the settings for the control
loop.
● The PID_3Step instruction and its associated technology object provide a PID controller
with specific settings for motor-activated valves. The technology object contains all of the
settings for the control loop. The PID_3Step controller provides two additional Boolean
outputs.
After creating the technology object, you must configure the parameters (Page 188). You
also adjust the autotuning parameters ("pre-tuning" during startup or manual "fine tuning") to
commission the operation of the PID controller (Page 190).

Table 8- 1

Inserting the PID instruction and the technology object

When you insert a PID instruction into your user program,
STEP 7 automatically creates a technology object and an
instance DB for the instruction. The instance DB contains
all of the parameters that are used by the PID instruction.
Each PID instruction must have its own unique instance
DB to operate properly.
After inserting the PID instruction and creating the
technology object and instance DB, you configure the
parameters for the technology object (Page 188).

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8.1 Inserting the PID instruction and technology object
Table 8- 2

(Optional) Creating a technology object from the project navigator

You can also create technology objects for your
project before inserting the PID instruction. By
creating the technology object before inserting a
PID instruction into your user program, you can
then select the technology object when you insert
the PID instruction.

To create a technology object, double-click the
"Add new object" icon in the project navigator.

Click the "Control" icon and select the technology
object for the type of PID controller (PID_Compact
or PID_3Step). You can create an optional name
for the technology object.
Click "OK" to create the technology object.

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8.2 PID_Compact instruction

8.2

PID_Compact instruction
The PID_Compact instruction provides a universal PID controller with integrated self-tuning
for automatic and manual mode.

Table 8- 3

PID_Compact instruction

LAD / FBD

SCL

"PID_Compact_1"(
Setpoint:=_real_in_,
Input:=_real_in_,
Input_PER:=_word_in_,
Disturbance:=_real_in_,
ManualEnable:=_bool_in_,
ManualValue:=_real_in_,
ErrorAck:=_bool_in_,
Reset:=_bool_in_,
ModeActivate:=_bool_in_,
Mode:=_int_in_,
ScaledInput=>_real_out_,
Output=>_real_out_,
Output_PER=>_word_out_,
Output_PWM=>_bool_out_,
SetpointLimit_H=>_bool_out_,
SetpointLimit_L=>_bool_out_,

Description
PID_Compact provides a PID controller with
self-tuning for automatic and manual mode.
PID_Compact is a PID T1 controller with
anti-windup and weighting of the P- and Dcomponent.

InputWarning_H=>_bool_out_,
InputWarning_L=>_bool_out_,
State=>_int_out_,
Error=>_bool_out_,
ErrorBits=>_dword_out_);
1

STEP 7 automatically creates the technology object and instance DB when you insert the instruction. The instance DB
contains the parameters of the technology object.

In the SCL example, "PID_Compact_1" is the name of the instance DB.

Table 8- 4

Data types for the parameters

Parameter and type

Data type

Description

Setpoint

Real

Setpoint of the PID controller in automatic mode. (Default value: 0.0)

Input

Real

A tag of the user program is used as the source of the process value.
(Default value: 0.0)
If you are using the Input parameter, you must set
Config.InputPerOn = FALSE.

Input_PER

Word

An Analog input is used as the source of the process value. (Default
value: W#16#0)
If you are using the Input_PER parameter, you must set
Config.InputPerOn = TRUE.

Disturbance

Real

Disturbance variable or pre-control value

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8.2 PID_Compact instruction

Parameter and type
ManualEnable

Data type

Description

Bool

Enables or disables the manual operation mode. (Default value:
FALSE):
•

A FALSE to TRUE edge activates "manual mode", while State = 4,
Mode remains unchanged.
As long as ManualEnable = TRUE, you cannot change the
operating mode using a rising edge at ModeActivate or use the
commissioning dialog.

A TRUE to FALSE edge activates the operating mode that is
assigned by Mode.
Note: We recommend that you change the operating mode using
ModeActivate only.

•

ManualValue

Real

Output value for manual operation. (Default value: 0.0)
You can use values from Config.OutputLowerLimit to
Config.OutputUpperLimit.

ErrorAck

Bool

Resets the ErrorBits and warning outputs. FALSE to TRUE edge

Reset

Bool

Restarts the controller. (Default value: FALSE):
•

FALSE to TRUE edge:
–

Switches to "inactive" mode

–

Resets the ErrorBits and warning outputs

–

Clears Integral action

–

Maintains PID parameters

•

As long as Reset = TRUE, PID_Compact remains in "Inactive"
mode (State = 0).

•

TRUE to FALSE edge:
–

PID_Compact switches to the operating mode that is saved in
the Mode parameter.

ModeActivate

Bool

The PID_Compact switches to the operating mode that is saved in the
Mode parameter. FALSE to TRUE edge:

Mode

Int

The desired PID mode; Activated on the leading edge of the Mode
Activate input.

ScaledInput

OUT

Real

Scaled process value. (Default value: 0.0)

Output1

OUT

Real

Output value in REAL format. (Default value: 0.0)

Output_PER1

OUT

Word

Analog output value. (Default value: W#16#0)

Output_PWM1

OUT

Bool

Output value for pulse width modulation. (Default value: FALSE)
On and Off times form the output value.

SetpointLimit_H

OUT

Bool

Setpoint high limit. (Default value: FALSE)
If SetpointLimit_H = TRUE, the absolute setpoint upper limit is reached
(Setpoint ≥ Config.SetpointUpperLimit).
The setpoint is limited to Config.SetpointUpperLimit.

SetpointLimit_L

OUT

Bool

Setpoint low limit. (Default value: FALSE)
If SetpointLimit_L = TRUE, the absolute setpoint lower limit is reached
(Setpoint ≤ Config.SetpointLowerLimit).
The setpoint is limited to Config.SetpointLowerLimit.

InputWarning_H

OUT

Bool

If InputWarning_H = TRUE, the process value has reached or
exceeded the warning high limit. (Default value: FALSE)

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8.2 PID_Compact instruction

Parameter and type

Data type

Description

InputWarning_L

OUT

Bool

If InputWarning_L = TRUE, the process value has reached or fallen
below the warning low limit. (Default value: FALSE)

State

OUT

Int

Current operating mode of the PID controller. (Default value: 0)
You can change the operating mode using the Mode input parameter
and a rising edge at ModeActivate:

Error

OUT

Bool

•

State = 0: Inactive

•

State = 1: Pre-tuning

•

State = 2: Manual fine tuning

•

State = 3: Automatic mode

•

State = 4: Manual mode

•

State = 5: Substitute output value with error monitoring

If Error = TRUE, at least one error message is pending in this cycle.
(Default value: FALSE)
Note: The Error parameter in V1.x PID was the ErrorBits field that
contained the error codes. It is now a Boolean flag indicating that an
error has occurred.

ErrorBits

OUT

DWord

The PID_Compact instruction ErrorBits parameters table (Page 177)
defines the error messages that are pending. (Default value:
DW#16#0000 (no error)). ErrorBits is retentive and is reset upon a
rising edge at Reset or ErrorAck.
Note: In V1.x, the ErrorBits parameter was defined as the Error
parameter and did not exist.

You can use the outputs of the Output, Output_PER, and Output_PWM parameters in parallel.

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8.2 PID_Compact instruction

Operation of the PID_Compact controller

Figure 8-1

Operation of the PID_Compact controller

Figure 8-2

Operation of the PID_Compact controller as a PIDT1 controller with anti-windup

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8.3 PID_Compact instruction ErrorBit parameters

8.3

PID_Compact instruction ErrorBit parameters
If several errors are pending, the values of the error codes are displayed by means of binary
addition. The display of error code 0003, for example, indicates that the errors 0001 and
0002 are also pending.
Table 8- 5

PID_Compact instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

0000

No error

0001

1, 2

The Input parameter is outside the process value limits.
Input > Config.InputUpperLimit
Input < Config.InputLowerLimit

0002

2, 3

Invalid value at the Input_PER parameter. Check whether an error is
pending at the analog input.

0004 4

Error during fine tuning. Oscillation of the process value could not be
maintained.

0008 4

Error at start of pre-tuning. The process value is too close to the setpoint.
Start fine tuning.

0010 4

The setpoint was changed during tuning.
Note: You can set the permitted fluctuation on the setpoint at the
CancelTuningLevel tag.

0020

Pre-tuning is not permitted during fine tuning.
Note: If ActivateRecoverMode = TRUE before the error occurred,
PID_Compact remains in fine tuning mode.

0080 4

Error during pre-tuning. Incorrect configuration of output value limits.
Check whether the limits of the output value are configured correctly and
match the control logic.

0100 4

Error during fine tuning resulted in invalid parameters.

0200

Invalid value at the Input parameter: Value has an invalid number format.

2, 3

0400 2, 3

Calculation of the output value failed. Check the PID parameters.

0800

Sampling time error: PID_Compact is not called within the sampling time of
the cyclic interrupt OB.

1, 2

1000 2, 3

Invalid value at the Setpoint parameter: Value has an invalid number format.

10000

Invalid value at the ManualValue parameter: Value has an invalid number
format.
Note: If ActivateRecoverMode = TRUE before the error occurred,
PID_Compact uses SubstituteOutput as the output value. As soon as you
assign a valid value in the ManualValue parameter, PID_Compact uses it as
the output value.

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8.3 PID_Compact instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

20000

Invalid value at the SubstituteValue tag: Value has an invalid number
format.
PID_Compact uses the output value low limit as the output value.
Note: If automatic mode was active before the error occurred,
ActivateRecoverMode = TRUE, and the error is no longer pending,
PID_Compact switches back to automatic mode.

40000

Invalid value at the Disturbance parameter: Value has an invalid number
format.
Note: If automatic mode was active and ActivateRecoverMode = FALSE
before the error occurred, Disturbance is set to zero. PID_Compact remains
in automatic mode.
Note: If pre-tuning or fine tuning mode was active and ActivateRecoverMode
= TRUE before the error occurred, PID_Compact switches to the operating
mode that is saved in the Mode parameter. If Disturbance in the current
phase has no effect on the output value, tuning is not canceled.

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,
PID_Compact remains in automatic mode.

Note: If pre-tuning or fine tuning mode was active before the error occurred and
ActivateRecoverMode = TRUE, PID_Compact switches to the operating mode that is saved in the
Mode parameter.

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,
PID_Compact outputs the configured substitute output value. As soon as the error is no longer
pending, PID_Compact switches back to automatic mode.

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_Compact cancels the tuning
and switches to the operating mode that is saved in the Mode parameter.

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8.4 PID_3Step instruction

8.4

PID_3Step instruction
The PID_3Step instruction configures a PID controller with self-tuning capabilities that has
been optimized for motor-controlled valves and actuators.

Table 8- 6

PID_3Step instruction

LAD / FBD

SCL

"PID_3Step_1"(
SetpoInt:=_real_in_,
Input:=_real_in_,
ManualValue:=_real_in_,
Feedback:=_real_in_,
InputPer:=_word_in_,
FeedbackPer:=_word_in_,
Disturbance:=_real_in_,
ManualEnable:=_bool_in_,
ManualUP:=_bool_in_,
ManualDN:=_bool_in_,
ActuatorH:=_bool_in_,
ActuatorL:=_bool_in_,
ErrorAck:=_bool_in_,
Reset:=_bool_in_,
ModeActivate:=_bool_in_,
Mode:=_int_in_,
ScaledInput=>_real_out_,
ScaledFeedback=>_real_out_,
ErrorBits=>_dword_out_,
OutputPer=>_word_out_,
State=>_int_out_,
OutputUP=>_bool_out_,
OutputDN=>_bool_out_,
SetpoIntLimitH=>_bool_out_,
SetpoIntLimitL=>_bool_out_,
InputWarningH=>_bool_out_,
InputWarningL=>_bool_out_,
Error=>_bool_out_,
ErrorBits=>_dword_out_);

Description
PID_3Step configures a PID controller with
self-tuning capabilities that has been
optimized for motor-controlled valves and
actuators. It provides two Boolean outputs.
PID_3Step is a PID T1controller with antiwindup and weighting of the P- and Dcomponents.

STEP 7 automatically creates the technology object and instance DB when you insert the instruction. The instance DB
contains the parameters of the technology object.

In the SCL example, "PID_3Step_1" is the name of the instance DB.

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8.4 PID_3Step instruction
Table 8- 7

Data types for the parameters

Parameter and type

Data type

Description

Setpoint

Real

Setpoint of the PID controller in automatic mode. (Default value: 0.0)

Input

Real

A tag of the user program is used as the source of the process value.
(Default value: 0.0)
If you are using the Input parameter, you must set
Config.InputPerOn = FALSE.

Input_PER

Word

An Analog input is used as the source of the process value. (Default
value: W#16#0)
If you are using the Input_PER parameter, you must set
Config.InputPerOn = TRUE.

Actuator_H

Bool

Digital position feedback of the valve for the high end stop
If Actuator_H = TRUE, the valve is at the high end stop and is no longer
moved in this direction. (Default value: FALSE)

Actuator_L

Bool

Digital position feedback of the valve for the low end stop
If Actuator_L = TRUE, the valve is at the low end stop and is no longer
moved in this direction. (Default value: FALSE)

Feedback

Real

Position feedback of the valve. (Default value: 0.0)
If you are using the Feedback parameter, you must set
Config.FeedbackPerOn = FALSE.

Feedback_PER

Int

Analog feedback of the valve position. (Default value: W#16#0)
If you are using the Feedback_PER parameter, you must set
Config.FeedbackPerOn = TRUE. Feedback_PER is scaled, based upon
the following tags:
•

Config.FeedbackScaling.LowerPointIn

•

Config.FeedbackScaling.UpperPointIn

•

Config.FeedbackScaling.LowerPointOut

•

Config.FeedbackScaling.UpperPointOut

Disturbance

Real

Disturbance variable or pre-control value

ManualEnable

Bool

Enables or disables the manual operation mode. (Default value:
FALSE):
•

A TRUE to FALSE edge activates the operating mode that is
assigned by Mode.
Note: We recommend that you change the operating mode using
ModeActivate only.

•

ManualValue

Real

Process value for manual operation. (Default value: 0.0)
In manual mode, you specify the absolute position of the valve.
ManualValue is evaluated only if you are using OutputPer, or if position
feedback is available.

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Parameter and type
ManualUP

Data type

Description

Bool

•

Manual_UP = TRUE:
–

The valve is opened even if you use Output_PER or a position
feedback. The valve is no longer moved if the high end stop has
been reached.

–

See also Config.VirtualActuatorLimit

Manual_DN = FALSE:
–

If you use Output_PER or a position feedback, the valve is
moved to ManualValue. Otherwise, the valve is no longer
moved.

ErrorAck

Bool

Resets the ErrorBits and warning outputs. FALSE to TRUE edge

Reset

Bool

Restarts the controller. (Default value: FALSE):
•

FALSE to TRUE edge:
–

Switches to "inactive" mode

–

Resets the ErrorBits and warning outputs

–

Clears Integral action

–

Maintains PID parameters

•

As long as Reset = TRUE, PID_3Step remains in "Inactive" mode
(State = 0).

•

TRUE to FALSE edge:
–

PID_3Step switches to the operating mode that is saved in the
Mode parameter.

ModeActivate

Bool

The PID_3Step switches to the mode that is saved in the Mode
parameter. FALSE to TRUE edge:

Mode

Int

The desired PID mode; Activated on the leading edge of the Mode
Activate input.

ScaledInput

OUT

Real

Scaled process value

ScaledFeedback

OUT

Real

Scaled valve position feedback
Note: For an actuator without position feedback, the position of the
actuator indicated by ScaledFeedback is very imprecise.
ScaledFeedback can only be used for rough estimation of the current
position in this case.

Output_UP

OUT

Bool

Digital output value for opening the valve. (Default value: FALSE)
If Config.OutputPerOn = FALSE, the parameter Output_UP is used.

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Parameter and type

Data type

Description

Output_DN

OUT

Bool

Digital output value for closing the valve. (Default value: FALSE)

Output_PER

OUT

Word

If Config.OutputPerOn = FALSE, the parameter Output_DN is used.
Analog output value.
If Config.OutputPerOn = TRUE, the parameter Output_PER is used.
SetpointLimitH

OUT

Bool

Setpoint high limit. (Default value: FALSE)
If SetpointLimitH = TRUE, the absolute upper limit of the setpoint is
reached (Setpoint ≥ Config.SetpointUpperLimit).
Note: The setpoint is limited to (Setpoint ≥ Config.SetpointUpperLimit).

SetpointLimitL

OUT

Bool

Setpoint low limit. (Default value: FALSE)
If SetpointLimitL = TRUE, the absolute lower limit of the setpoint is
reached (Setpoint ≥ Config.SetpointLowerLimit).
Note: The setpoint is limited to (Setpoint ≥ Config.SetpointLowerLimit).

InputWarningH

OUT

Bool

If InputWarningH = TRUE, the input value has reached or exceeded the
warning high limit. (Default value: FALSE)

InputWarningL

OUT

Bool

If InputWarningL = TRUE, the input value has reached or exceeded the
warning low limit. (Default value: FALSE)

State

OUT

Int

Current operating mode of the PID controller. (Default value: 0)
You can change the operating mode using the Mode input parameter
and a rising edge at ModeActivate:

Error

OUT

Bool

•

State = 0: Inactive

•

State = 1: Pre-tuning

•

State = 2: Manual fine tuning

•

State = 3: Automatic mode

•

State = 4: Manual mode

•

State = 5: Substitute output value approach

•

State = 6: Transition time measurement

•

State = 7: Error monitoring

•

State = 8: Substitute output value approach with error monitoring\

•

State = 10: Manual mode without end stop signals

If Error = TRUE, at least one error message is pending. (Default value:
FALSE)
Note: The Error parameter in V1.x PID was the ErrorBits field that
contained the error codes. It is now a Boolean flag indicating that an
error has occurred.

ErrorBits

OUT

DWord

The PID_3Step instruction ErrorBits parameters table (Page 186)
defines the error messages that are pending. (Default value:
DW#16#0000 (no error)). ErrorBits is retentive and is reset upon a
rising edge at Reset or ErrorAck.
Note: In V1.x, the ErrorBits parameter was defined as the Error
parameter and did not exist.

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Figure 8-3

Operation of the PID_3Step controller as a PID T1 controller with anti-windup

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8.4 PID_3Step instruction

Figure 8-4

Operation of the PID_3Step controller without position feedback

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Figure 8-5

Operation of the PID_3Step controller with position feedback enabled

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8.5 PID_3Step instruction ErrorBit parameters

8.5

PID_3Step instruction ErrorBit parameters
If several errors are pending, the values of the error codes are displayed by means of binary
addition. The display of error code 0003, for example, indicates that the errors 0001 and
0002 are also pending.
Table 8- 8

PID_3STEP instruction ErrorBit parameters

ErrorBit (DW#16#...)

Description

0000

No error

0001

1, 2

The Input parameter is outside the process value limits.
Input > Config.InputUpperLimit
Input < Config.InputLowerLimit

0002

2, 3

Invalid value at the Input_PER parameter. Check whether an error is
pending at the analog input.

0004 4

Error during fine tuning. Oscillation of the process value could not be
maintained.

0010 4

The setpoint was changed during tuning.
Note: You can set the permitted fluctuation on the setpoint at the
CancelTuningLevel tag.

0020

Pre-tuning is not permitted during fine tuning.
Note: If ActivateRecoverMode = TRUE before the error occurred, PID_3Step
remains in fine tuning mode.

0080 4

Error during pre-tuning. Incorrect configuration of output value limits.
Check whether the limits of the output value are configured correctly and
match the control logic.

0100 4

Error during fine tuning resulted in invalid parameters.

0200 2, 3

Invalid value at the Input parameter: Value has an invalid number format.

0400 2, 3

Calculating the output value failed. Check the PID parameters.

0800

Sampling time error: PID_3Step is not called within the sampling time of the
cyclic interrupt OB.

1, 2

1000 2, 3
2000

1, 2, 5

Invalid value at the Setpoint parameter: Value has an invalid number format.
Invalid value at the Feedback_PER parameter.
Check whether an error is pending at the analog input.

4000 1, 2, 5

Invalid value at the Feedback parameter: Value has an invalid number
format.

8000 1, 2

Error during digital position feedback. Actuator_H = TRUE and Actuator_L =
TRUE.
The actuator cannot be moved to the substitute output value and remains in
its current position. Manual mode is not possible in this state.
In order to move the actuator from this state, you must deactivate the
"Actuator end stop" (Config.ActuatorEndStopOn = FALSE) or switch to
manual mode without end stop signals (Mode = 10).

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ErrorBit (DW#16#...)

Description

10000

Invalid value at the ManualValue parameter: Value has an invalid number
format.
The actuator cannot be moved to the manual value and remains in its
current position.
Assign a valid value in ManualValue or move the actuator in manual mode
with Manual_UP and Manual_DN.

20000

Invalid value at the SavePosition tag: Value has an invalid number format.
The actuator cannot be moved to the substitute output value and remains in
its current position.

40000

Invalid value at the Disturbance parameter: Value has an invalid number
format.
Note: If automatic mode was active and ActivateRecoverMode = FALSE
before the error occurred, Disturbance is set to zero. PID_3Step remains in
automatic mode.
Note: If pre-tuning or fine tuning mode was active and ActivateRecoverMode
= TRUE before the error occurred, PID_3Step switches to the operating
mode that is saved in the Mode parameter. If Disturbance in the current
phase has no effect on the output value, tuning is not canceled.
The error has no effect during transition time measurement.

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,
PID_3Step remains in automatic mode.

Note: If pre-tuning, fine tuning, or transition time measurement mode were active and
ActivateRecoverMode = TRUE before the error occurred, PID_3Step switches to the operating
mode that is saved in the Mode parameter.

Note: If automatic mode was active before the error occurred and ActivateRecoverMode = TRUE,
PID_3Step switches to "Approach substitute output value with error monitoring" or "Error
monitoring" mode. As soon as the error is no longer pending, PID_3Step switches back to
automatic mode.

Note: If ActivateRecoverMode = TRUE before the error occurred, PID_3Step cancels the tuning
and switches to the operating mode that is saved in the Mode parameter.

The actuator cannot be moved to the substitute output value and remains in its current position. In
manual mode, you can change the position of the actuator only with Manual_UP and Manual_DN,
and not with ManualValue.

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8.6 Configuring the PID controller

8.6

Configuring the PID controller
The parameters of the technology object determine the operation of the PID
controller. Use the icon to open the configuration editor.

Table 8- 9

Sample configuration settings for the PID_Compact instruction

Settings
Basic

Process
value

Description
Controller type

Selects the engineering units.

Invert the control logic

Allows selection of a reverse-acting PID loop.
•

If not selected, the PID loop is in direct-acting mode and the output of PID loop
increases if input value < setpoint.

•

If selected, the output of the PID loop increases if the input value > setpoint.

Enable last mode after
CPU restart

Restarts the PID loop after it is reset or if an input limit has been exceeded and
returned to the valid range.

Input

Selects either the Input parameter or the Input_PER parameter (for analog) for the
process value. Input_PER can come directly from an analog input module.

Output

Selects either the Output parameter or the Output_PER parameter (for analog) for
the output value. Output_PER can go directly to an analog output module.

Scales both the range and the limits for the process value. If the process value goes below the low limit or
above the high limit, the PID loop goes to inactive mode and sets the output value to 0.
To use Input_PER, you must scale the analog process value (input value).

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Table 8- 10

Sample configuration settings for the PID_3Step instruction

Settings
Basic

Description
Controller type

Selects the engineering units.

Invert the control logic

Allows selection of a reverse-acting PID loop.

Activate mode after
CPU restart

•

If not selected, the PID loop is in direct-acting mode, and the output of PID loop
increases if the input value < setpoint).

•

If selected, the output of the PID loop increases if the input value > setpoint.

Restarts the PID loop after it is reset or if an input limit has been exceeded and
returned to the valid range.
Set Mode to: Defines the mode that the user wants the PID to go to after restart.

Input

Selects either the Input parameter or the Input_PER parameter (for analog) for the
process value. Input_PER can come directly from an analog input module.

Output

Selects either to use the digital outputs (Output_UP and Output_DN) or to use the
analog output (Output_PER) for the output value.

Feedback

Selects the type of device status returned to the PID loop:
•

No feedback (default)

•

Feedback

•

Feedback_PER

Process
value

Scales both the range and the limits for the process value. If the process value goes below the low limit or
above the high limit, the PID loop goes to inactive mode and sets the output value to 0.

Actuator

Motor transition
time

Sets the time from open to close for the valve. (Locate this value on the data sheet or
the faceplate of the valve.)

Minimum ON time

Sets the minimum movement time for the valve. (Locate this value on the data sheet or
the faceplate of the valve.)

Minimum OFF
time

Sets the minimum pause time for the valve. (Locate this value on the data sheet or the
faceplate of the valve.)

To use Input_PER, you must scale the analog process value (input value).

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Settings

Advanced

Description
Reaction to error

Defines the behavior of the valve when an error is detected or when the PID loop is
reset. If you select to use a substitute position, enter the "Safety position". For analog
feedback or analog output, select a value between the upper or lower limit for the
output. For digital outputs, you can choose only 0% (off) or 100% (on).

Scale Position
Feedback1

•

"High end stop" and "Lower end stop" define the maximum positive position (fullopen) and the maximum negative position (full-closed). "High end stop" must be
greater than "Lower end stop".

•

"High limit process value" and "Low limit process value" define the upper and lower
positions of the valve during tuning and automatic mode.

•

"FeedbackPER" ("Low" and "High") defines the analog feedback of the valve
position. "FeedbackPER High" must be greater than "FeedbackPER Low".

Monitoring process Sets the warning high and low limits for the process value.
value
PID parameters

If the user wishes, he can enter his own PID tuning parameters in this window. The
“Enable Manual Entry” check box must be checked to allow this.

"Scale Position Feedback" is editable only if you enabled "Feedback" in the "Basic" settings.

8.7

Commissioning the PID controller
Use the commissioning editor to configure the PID controller for autotuning at startup
and for autotuning during operation. To open the commissioning editor, click the icon
on either the instruction or the project navigator.

Table 8- 11

Sample commissioning screen (PID_3Step)
•

Measurement: To display the setpoint, the
process value (input value) and the output value in a
real-time trend, enter the sample time and click the
"Start" button.

•

Tuning mode: To tune the PID loop, select either
"Pre-tuning" or "Fine tuning" (manual) and click the
"Start" button. The PID controller runs through
multiple phases to calculate system response and
update times. The appropriate tuning parameters are
calculated from these values.

After the completion of the tuning process, you can
store the new parameters by clicking the "Upload PID
parameters" button in the "PID Parameters" section of
the commissioning editor.
If an error occurs during tuning, the output value of the
PID goes to 0. The PID mode then is set to "inactive"
mode. The status indicates the error.

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PID start value control
You can edit the actual values of the PID configuration parameters so that the behavior of
the PID controller can be optimized in online mode.
Open the "Technology objects" for your PID controller and its "Configuration" object. To
access the start value control, click the "eyeglasses icon" in the upper left corner of the
dialog:

You can now change the value of any of your PID controller configuration parameters as
shown in the figure below.
You can compare the actual value to the project (offline) start value and the PLC (online)
start value of each parameter. This is necessary to compare online/offline differences of the
Technology object data block (TO-DB) and to be informed about the values that will be used
as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon
gives a visual indication to help easily identify online/offline differences:

The figure above shows the PID parameter screen with compare icons showing which
values are different between online and offline projects. A green icon indicates that the
values are the same; a blue/orange icon indicates that the values are different.

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Additionally, click the parameter button with the downward arrow to open a small window
that shows the project (offline) start value and the PLC (online) start value of each
parameter:

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Web server for easy Internet connectivity

The Web server provides Web page access to data about your CPU and to the process data
within the CPU. With these Web pages, you access the CPU with the Web browser of your
PC or mobile device. The standard web pages allow authorized users to perform a variety of
functions:
● You can change the operating mode (STOP and RUN) of the CPU.
● You can monitor and modify the status of the PLC tags.
● You can view and download any data logs being collected by the CPU.
● You can view the diagnostic buffer of the CPU.
● You can update the firmware of the CPU.
The Web server also allows you to create user-defined Web pages that can access CPU
data. You can develop these pages with the HTML authoring software of your choice. You
insert pre-defined "AWP" (Automation Web Programming) commands in your HTML code to
access the data in the CPU.
You set up users and privilege levels for the Web server in the device configuration for the
CPU in STEP 7.

Web browser requirement
The Web server supports the following PC Web browsers:
● Internet Explorer 8.0 or greater
● Mozilla Firefox 3.0 or greater
● Opera 11.0 or greater
● Google Chrome 21.0 or greater
● Apple Safari 6.0 or greater
The Web server supports the following mobile device Web browsers:
● Internet Explorer 8.0 or greater, for HMI panels
● Mobile Safari, iOS 5.0 or greater
● Mobile Android Browser, 2.3.4 or greater
● Mobile Google Chrome, Android 4.0 or greater
For browser-related restrictions that can interfere with the display of standard or user-defined
Web pages, see the topics about constraints (Page 196).

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9.1 Easy to use the standard Web pages

9.1

Easy to use the standard Web pages
Using the standard Web pages is easy! You only have to enable the Web server when
configuring the CPU.
The Start page displays a representation of
the CPU to which you are connected and lists
general information about the CPU.
If you log in as a user with the required
privileges, you can change the operating
mode of the CPU (STOP and RUN) or flash
the LEDs.

The Variable Status page allows you to
monitor or modify any of the I/O or memory
data in your CPU. You must log in with
privileges to read data to monitor values, and
with privileges to write data to modify values.
You can enter a direct address (such as I0.0),
a PLC tag name, or a tag from a specific
program block. The data values automatically
refresh until you disable the automatic refresh
option.
The Diagnostic Buffer page displays the
diagnostic buffer, and is accessible to users
with privileges to query diagnostics. You can
select the range of diagnostic entries to be
displayed.
The diagnostic entries list the events that
occurred and the CPU time and date of when
the event occurred. Select the individual event
to display detailed information about that
event.

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The File Browser page allows you to view,
download, or edit files in the load memory of
the CPU such as data logs (Page 112) and
recipes. Unless the CPU has Level 4
protection, all users can view the files from the
File Browser page. Users with privileges to
modify files can delete, edit and rename files.

The Module Information page in addition to
displaying information about the modules in
your station allows you to update the version
of firmware in your CPU or other modules that
support firmware update. Users with privileges
to query diagnostics can view module
information. Users with privileges to perform a
firmware update can update firmware.

Other standard web pages display information about the CPU (such as the serial number,
the version and the order number) and about the communication parameters (such as
network addresses, physical properties of the communication interfaces, and communication
statistics).
WARNING
Unauthorized access to the CPU through the Web server
Unauthorized access to the CPU or changing PLC variables to invalid values could disrupt
process operation and could result in death, severe personal injury and/or property
damage.
Because enabling the Web server allows authorized users to perform operating mode
changes, writes to PLC data, and firmware updates, Siemens recommends that you
observe the following security practices:
• Enable access to the Web server only with the HTTPS protocol.
• Password-protect Web server user IDs with a strong password. Strong passwords are at
least ten characters in length, mix letters, numbers, and special characters, are not
words that can be found in a dictionary, and are not names or identifiers that can be
derived from personal information. Keep the password secret and change it frequently.
• Do not extend the default minimum privileges of the "Everybody" user.
• Perform error-checking and range-checking on your variables in your program logic
because Web page users can change PLC variables to invalid values.
• Use a secure Virtual Private Network (VPN) to connect to the S7-1200 PLC Web server
from a location outside your protected network.

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9.2 Constraints that can affect the use of the Web server

9.2

Constraints that can affect the use of the Web server
The following IT considerations can affect your use of the Web server:
● Typically, you must use the IP address of the CPU to access the standard Web pages or
user-defined Web pages, or the IP address of a wireless router with a port number. If
your Web browser does not allow connecting directly to an IP address, see your IT
administrator. If your local policies support DNS, you can connect to the IP address
through a DNS entry to that address.
● Firewalls, proxy settings, and other site-specific restrictions can also restrict access to the
CPU. See your IT administrator to resolve these issues.
● The standard Web pages use JavaScript and cookies. If your Web browser settings
disable JavaScript or cookies, enable them. If you cannot enable them, some features
are restricted. Use of JavaScript and cookies in user-defined Web pages is optional. If
used, you must enable them in your browser.
● The Web server supports Secure Sockets Layer (SSL). You can access the standard
Web pages and user-defined Web pages with an URL of either http://ww.xx.yy.zz or
https://ww.xx.yy.zz, where "ww.xx.yy.zz" represents the IP address of the CPU.
● Siemens provides a security certificate for secure access to the Web server. From the
Introduction standard Web page, you can download and import the certificate into the
Internet options of your Web browser. If you choose to not import the certificate, you will
get a security verification prompt every time you access the Web server with https://.

Number of connections
The Web server supports a maximum of 30 active HTTP connections. Various actions
consume the 30 connections, depending on the Web browser that you use and the number
of different objects per page (.css files, images, additional .html files). Some connections
persist while the Web server is displaying a page; other connections do not persist after the
initial connection.
If, for example, you are using Mozilla Firefox 8, which supports a maximum of six persistent
connections, you could use five browser or browser tab instances before the Web server
starts dropping connections. In the case where a page is not using all six connections, you
could have additional browser or browser tab instances.
Also be aware that the number of active connections can affect page performance.
Note
Log off prior to closing Web server
If you have logged in to the Web server, be sure to log off prior to closing your Web browser.
The Web server supports a maximum of seven concurrent logins.

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9.2 Constraints that can affect the use of the Web server

9.2.1

Feature restrictions when the Internet options disable JavaScript
The standard Web pages use HTML, JavaScript, and cookies. If your site restricts the use of
JavaScript and cookies, then enable them for the pages to function properly. If you cannot
enable JavaScript for your Web browser, the features that use JavaScript controls cannot
run.

General
The pages do not update dynamically. You must manually refresh the page with the Refresh
icon to view fresh data.

Diagnostic Buffer page
The Diagnostic Buffer page uses JavaScript as follows:
● Displaying the event details: With JavaScript, you select a row in the diagnostic buffer to
see the details in the bottom section. Without JavaScript, you must click the event field
hyperlink of a diagnostic buffer entry to see the event data in the bottom section.
● Changing the range of diagnostic buffer entries to view: With JavaScript, you use the
drop-down list at the top to select the range of diagnostic buffer entries to view, and the
page automatically updates. Without JavaScript, you use the drop-down list at the top to
select the range of diagnostic buffer entries to view, but you must then click the "Go" link
to update the diagnostic buffer page with the range you selected from the drop-down list.
Note that the "Go" and the event field hyperlinks are only visible when JavaScript is not
enabled. They are not necessary and therefore are not present when JavaScript is enabled.

Module Information page
Without JavaScript enabled, the following restrictions apply:
● You cannot filter the data.
● You cannot sort fields.

Variable Status page
Without JavaScript enabled, the following restrictions apply:
● After you enter each variable, you must manually set the focus to the "New variable" row
to enter a new variable.
● Selecting a display format does not automatically change the data value display to the
selected format. You must click the "Monitor value" button to refresh the display with the
new format.

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9.3 Easy to create user-defined web pages

9.2.2

Feature restrictions when the Internet options do not allow cookies
If you disable cookies in your Web browser, the following restrictions apply:
● You cannot log in.
● You cannot change the language setting.
● You cannot switch from UTC time to PLC time. Without cookies, all times are in UTC
time.

9.3

Easy to create user-defined web pages

9.3.1

Easy to create custom "user-defined" web pages
The S7-1200 Web server also provides the means for you to create your own applicationspecific HTML pages that incorporate data from the PLC. Use the HTML editor of your
choice to create these pages, and then download them to the CPU from where they are
accessible from the standard Web pages.

①

HTML files with embedded AWP commands

This process involves several tasks:
● Create the HTML pages with an HTML editor, such as Microsoft Frontpage
● Include AWP commands in HTML comments in the HTML code: The AWP commands
are a fixed set of commands for accessing CPU information.
● Configure STEP 7 to read and process the HTML pages.
● Generate the program blocks from the HTML pages.
● Program STEP 7 to control the use of the HTML pages.
● Compile and download the program blocks to the CPU.
● Access the user-defined Web pages from your PC or mobile device.

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9.3 Easy to create user-defined web pages
You can use the software package of your choice to create your own HTML pages for use
with the Web server. Be sure that your HTML code is compliant to the HTML standards of
the W3C (World Wide Web Consortium). STEP 7 does not perform any verification of your
HTML syntax.
You can use a software package that lets you design in WYSIWYG or design layout mode,
but you need to be able to edit your HTML code in pure HTML form. Most Web authoring
tools provide this type of editing; otherwise, you can always use a simple text editor to edit
the HTML code. Include the following line in your HTML page to set the charset for the page
to UTF-8:

Also be sure to save the file from the editor in UTF-8 character encoding.
You use STEP 7 to compile everything in your HTML pages into STEP 7 data blocks. These
data blocks consist of one control data block that directs the display of the Web pages and
one or more fragment data blocks that contain the compiled Web pages. Be aware that
extensive sets of HTML pages, particularly those with lots of images, require a significant
amount of load memory space for the fragment DBs. If the internal load memory of your CPU
is not sufficient for your user-defined Web pages, use a memory card to provide external
load memory.
To program your HTML code to use data from the S7-1200, you include AWP commands as
HTML comments. When finished, save your HTML pages to your PC and note the folder
path where you save them.
Note
The file size limit for HTML files containing AWP command is 64 kilobytes. You must keep
your file size below this limit.

Refreshing user-defined Web pages
User-defined Web pages do not automatically refresh. It is your choice whether to program
the HTML to refresh the page or not. For pages that display PLC data, refreshing periodically
keeps the data current. For HTML pages that serve as forms for data entry, refreshing can
interfere with the user entering data. If you want your entire page to automatically refresh,
you can add this line to your HTML header, where "10" is the number of seconds between
refreshes:

You can also use JavaScript or other HTML techniques to control page or data refreshing.
For this, refer to documentation on HTML and JavaScript.

9.3.2

Constraints specific to user-defined Web pages
The constraints for standard Web pages also apply to user-defined Web pages. In addition,
user-defined Web pages have some specific considerations.

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Load memory space
Your user-defined Web pages become data blocks when you click "Generate blocks", which
require load memory space. If you have a memory card installed, you have up to the
capacity of your memory card as external load memory space for the user-defined Web
pages.
If you do not have a memory card installed, these blocks take up internal load memory
space, which is limited according to your CPU model.
You can check the amount of load memory space that is used and the amount that is
available from the Online and Diagnostic tools in STEP 7. You can also look at the properties
for the individual blocks that STEP 7 generates from your user-defined Web pages and see
the load memory consumption.
Note
If you need to reduce the space required for your user-defined Web pages, reduce your use
of images if applicable.

9.3.3

Configuration of a user-defined Web page
To configure the user-defined Web pages, edit the "Web server" properties of the CPU.

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After you enable the Web server functionality, enter the following information:
● Name and the current location of the HTML default start page to generate the DBs for the
user-defined Web pages.
● Name for your application (optional). The application name is used to further
subcategorize or group web pages. When an application name exists, the URL will
appear in the following format:
http://ww.xx.yy.zz/awp//.html
● Filename extensions to be examined for the presence of AWP commands. By default,
STEP 7 analyzes files with .htm, .html, or .js extensions. If you have additional file
extensions, append them.
● Identification numbers for the control DB number and the initial fragment DB.
After configuring the Web server, click the "Create blocks" button to generate the DBs from
the HTML pages. After you generate the DBs, your Web pages are a part of your user
program. The control data block for the operation of your Web pages, and the "fragment"
DBs contain all of the HTML pages.

9.3.4

Using the WWW instruction
The WWW instruction allows your user-defined Web pages to be accessible from the
standard Web pages. Your user program only has to execute the WWW instruction once to
enable access to the user-defined Web pages. You might, however, choose to make the
user-defined Web pages available only under certain circumstances. Your user program
could then call the WWW instruction according to your application requirements.

Table 9- 1

WWW instruction

LAD / FBD

SCL

ret_val := #WWW(
ctrl_db:=_uint_in_);

Description
Identifies the control DB to be used for the userdefined Web pages.
The control data block is the input parameter to
the WWW instruction and specifies the content of
the pages as represented in the fragment data
blocks, as well as state and control information.

Your user program typically uses the control DB directly as created by the "Create blocks"
process, with no additional manipulation. However, the user program can set global
commands in the control DB to deactivate the web server, or to subsequently reactivate it.
Also, for user-defined pages that you create as manual fragment DBs, the user program
must control the behavior of these pages through a request table in the control DB.

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The CPU provides motion control functionality for the operation of stepper motors and servo
motors with pulse interface. The motion control functionality takes over the control and
monitoring of the drives.
● The "Axis" technology object configures the mechanical drive data, drive interface,
dynamic parameters, and other drive properties.
● You configure the pulse and direction outputs of the CPU for controlling the drive.
● Your user program uses the motion control instructions to control the axis and to initiate
motion tasks.
● Use the PROFINET interface to establish the online connection between the CPU and the
programming device. In addition to the online functions of the CPU, additional
commissioning and diagnostic functions are available for motion control.
Note
Changes that you make to the motion control configuration and download in RUN mode
do not take effect until the CPU transitions from STOP to RUN mode.

①
②
③
④

PROFINET
Pulse and direction outputs
Power section for stepper motor
Power section for servo motor

The DC/DC/DC variants of the CPU S7-1200 have onboard
outputs for direct control of drives. The relay variants of the
CPU require the signal board with DC outputs for drive
control.

A signal board (SB) expands the onboard I/O to include a few additional I/O points. An SB
with two digital outputs can be used as pulse and direction outputs to control one motor. An
SB with four digital outputs can be used as pulse and direction outputs to control two motors.
Built-in relay outputs cannot be used as pulse outputs to control motors. Whether you use
onboard I/O or SB I/O or a combination of both, you can have a maximum number of four
pulse generators.

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The four pulse generators have default I/O assignments; however, they can be configured to
any digital output on the CPU or SB. Pulse generators on the CPU cannot be assigned to
SMs or to distributed I/O.
Note
Pulse-train outputs cannot be used by other instructions in the user program
When you configure the outputs of the CPU or signal board as pulse generators (for use with
the PWM or motion control instructions), the corresponding output addresses no longer
control the outputs. If your user program writes a value to an output used as a pulse
generator, the CPU does not write that value to the physical output.

Table 10- 1

Maximum number of controllable drives

Type of CPU

CPU 1211C

CPU 1212C

CPU 1214C

CPU 1215C

CPU 1217C

Onboard I/O;
No SB installed

With an SB
(2 x DC outputs)

With an SB
(4 x DC outputs)

With
direction

Without
direction

With
direction

Without
direction

With
direction

Without
direction

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

DC/DC/DC

AC/DC/RLY

DC/DC/RLY

DC/DC/DC

Note
The maximum number of pulse generators is four.
Whether you use onboard I/O, SB I/O, or a combination of both, you can have a maximum
number of four pulse generators.

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Table 10- 2

CPU output: maximum frequency

CPU

CPU output channel

Pulse and direction
output

A/B, quadrature, up/down,
and pulse/direction

1211C

Qa.0 to Qa.3

100 kHz

1212C

Qa.0 to Qa.3

100 kHz

Qa.4, Qa.5

20 kHz

Qa.0 to Qa.3

100kHz

Qa.4 to Qb.1

20 kHz

DQa.0 to DQa.3

1 MHz

100 kHz

1214C and 1215C
1217C

(.0+, .0- to .3+, .3-)
DQa.4 to DQb.1

Table 10- 3

Table 10- 4

SB signal board output: maximum frequency (optional board)

SB signal board

SB output channel

Pulse and direction
output

A/B, quadrature, up/down,
and pulse/direction

SB 1222, 200 kHz

DQe.0 to DQe.3

200kHz

200 kHz

SB 1223, 200 kHz

DQe.0, DQe.1

200kHz

200 kHz

SB 1223

DQe.0, DQe.1

20 kHz

Limit frequencies of pulse outputs

Pulse output

Frequency

Onboard

4 PTO: 2 Hz ≤ f ≤ 1 MHz, 4 PTO: 2 Hz ≤ f ≤ 100 KHz, or any combination of
these values for 4 PTOs.1 2

Standard SB

2 Hz ≤ f ≤ 20 KHz

High-speed SBs

2 Hz ≤ f ≤ 200 KHz

See the table below for four possible CPU 1217C output speed combinations.

See the table below for four possible CPU 1211C, CPU 1212C, CPU 1214C, or CPU 1215C output speed combinations.

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CPU 1217C example output speed configurations
Note
The CPU 1217C can generate pulse outputs up to 1 MHz, using the onboard differential
outputs.
The examples below show four possible output speed combinations:
● Example 1: 4 - 1 MHz PTOs, no direction output
● Example 2: 1 - 1 MHz, 2 - 100 KHz, and 1 - 20 KHz PTOs, all with direction output
● Example 3: 4 - 200 KHz PTOs, no direction output
● Example 4: 2 - 100 KHz PTOs and 2 - 200 KHz PTOs, all with direction output
P = Pulse

CPU on-board outputs

High-speed SB outputs

Standard
SB
outputs

200 KHz Outputs (Q)

20 KHz
Outputs
(Q)

D = Direction
1 MHz Outputs (Q)

Ex. 1:
4-1
MHz
(no
direction
output)

PTO1

Ex. 2: 1 1 MHz; 2
- 100
and 1 20 KHz
(all with
direction
output)

PTO1

Ex. 3:
4 - 200
KHz (no
direction
output)

PTO1

Ex. 4:
2 - 100
KHz;
2 - 200
KHz (all
with
direction
output)

PTO1

0.0+ 0.1+

0.2+

0.3+

0.0-

0.2-

0.3-

0.1-

0.4

0.5

0.6

0.7

1.0

1.1

4.0

4.1

4.2

4.3

P
P

PTO3
PTO4

PTO2

PTO3

PTO4

PTO3

4.1

PTO3

PTO2

4.0

PTO2

100 KHz Outputs (Q)

P
P

D
P

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CPU 1211C, CPU 1212C, CPU 1214C, and CPU 1215C example output speed configurations
The examples below show four possible output speed combinations:
● Example 1: 4 - 100 KHz PTOs, no direction output
● Example 2: 2 - 100 KHz PTOs and 2 - 20 KHz PTOs, all with direction output
● Example 3: 4 - 200 KHz PTOs, no direction output
● Example 4: 2 - 100 KHz PTOs and 2 - 200 KHz PTOs, all with direction output
P = Pulse

CPU on-board outputs

High-speed SB outputs

Low-speed
SB outputs

200KHz Outputs (Q)

20Kz
Outputs
(Q)

D = Direction
100KHz Outputs (Q)

0.0

0.1

0.2

0.3

20KHz Outputs (Q)

0.4

0.5

0.6

0.7

1.0

1.1

4.0

4.1

4.2

4.3

4.0

4.1

CPU 1211C

Ex. 1:
4 - 100
KHz (no
direction
output)

PTO1

Ex. 2:
2 - 100
KHz;
2 - 20
KHz (all
with
direction
output)

PTO1

Ex. 3:
4 - 200
KHz (no
direction
output)

PTO1

Ex. 4:
2 - 100
KHz;
2 - 200
KHz (all
with
direction
output)

PTO1

CPU 1212C

CPU
1212C

CPU 1214C

CPU
1214C

CPU 1214C

CPU 1215C

CPU
1215C

CPU 1215C

PTO2

PTO3

PTO4

P
P

PTO2

PTO3

PTO4

D
P

PTO2

PTO3

PTO4

P
P

PTO2
PTO3
PTO4

D
P

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10.1 Phasing

10.1

Phasing
You have four options for the "Phasing" interface to the stepper/servo drive. These options
are as follows:
● PTO (pulse A and direction B): If you select a PTO (pulse A and direction B) option, then
one output (P0) controls the pulsing and one output (P1) controls the direction. P1 is high
(active) if pulsing is in the positive direction. P1 is low (inactive) if pulsing is in the
negative direction:

● PTO (count up A and count down B): If you select a PTO (count up A and count down B)
option, then one output (P0) pulses for positive directions and a different output (P1)
pulses for negative directions:

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10.1 Phasing
● PTO (A/B phase-shifted): If you select a PTO (A/B phase-shifted) option, then both
outputs pulse at the speed specified, but 90 degrees out-of-phase. It is a 1X
configuration, meaning one pulse is the amount of time between positive transitions of
P0. In this case, the direction is determined by which output transitions high first. P0
leads P1 for the positive direction. P1 leads P0 for the negative direction.
The number of pulses generated is based upon the number of 0 to 1 transitions of Phase
A. The phase relationship determines the direction of movement:
PTO (A/B phase-shifted)
Phase A leads phase B (positive movement)

Phase A lags phase B (negative movement)

Number of pulses

● PTO (A/B phase-shifted - fourfold): If you select a PTO (A/B phase-shifted - fourfold)
option, then both outputs pulse at the speed specified, but 90 degrees out-of-phase. The
fourfold is a 4X configuration, meaning one pulse is the transition of each output (both
positive and negative). In this case, the direction is determined by which output
transitions high first. P0 leads P1 for the positive direction. P1 leads P0 for the negative
direction.
Fourfold is based upon positive and negative transitions of both Phase A and Phase B.
You configure the number of transitions. The phase relationship (A leading B or B leading
A) determines the direction of movement.
PTO (A/B phase-shifted - fourfold)
Phase A leads phase B (positive movement)

Phase A lags phase B (negative movement)

Number of pulses

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10.2 Configuring a pulse generator
● PTO (pulse and direction (direction de-selected)): If you de-select the direction output in a
PTO (pulse and direction (direction de-selected)), then output (P0) controls the pulsing.
Output P1 is not used and is available for other program uses. Only positive motion
commands are accepted by the CPU in this mode. Motion control restricts you from
making illegal negative configurations when you select this mode. You can save an
output if your motion application is in one direction only. Single phase (one output) is
shown in the figure below (assuming positive polarity):

10.2

Configuring a pulse generator
1. Add a Technology object:
– In the Project tree, expand the node "Technology Objects" and select "Add new
object".
– Select the "Axis" icon (rename if required) and click "OK" to open the configuration
editor for the axis object.
– Display the "Select PTO for Axis Control" properties under the "Basic parameters" and
select the desired pulse.
Note
If the PTO has not been previously configured in the CPU Properties, the PTO is
configured to use one of the onboard outputs.
If you use an output signal board, then select the "Device configuration" button to go
to the CPU Properties. Under "Parameter assignment", in the "Pulse options",
configure the output source to a signal board output.
– Configure the remaining Basic and Extended parameters.
2. Program your application: Insert the MC_Power instruction in a code block.
– For the Axis input, select the axis technology object that you created and configured.
– Setting the Enable input to TRUE allows the other motion instructions to function.
– Setting the Enable input FALSE cancels the other motion instructions.
Note
Include only one MC_Power instruction per axis.
3. Insert the other motion instructions to produce the required motion.

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10.3 Configuring the axis

Note
Configuring a pulse generator to signal board outputs: Select the "Pulse generators
(PTO/PWM)" properties for a CPU (in Device configuration) and enable a pulse generator.
Two pulse generators are available for each S7-1200 CPU V1.0, V2.0, V2.1, and V2.2.
S7-1200 CPU V3.0 and V4.0 CPUs have four pulse generators available. In this same
configuration area under "Pulse options", select Pulse generator used as: "PTO".

Note
The CPU calculates motion tasks in "slices" or segments of 10 ms. As one slice is being
executed, the next slice is waiting in the queue to be executed. If you interrupt the motion
task on an axis (by executing another new motion task for that axis), the new motion task
may not be executed for a maximum of 20 ms (the remainder of the current slice plus the
queued slice).

10.3

Configuring the axis
STEP 7 provides the configuration tools, the commissioning tools, and the diagnostic tools
for the "Axis" technology object.

①
②
③

Drive
Technology object

④
⑤

Commissioning
Diagnostics

Configuration

Note
For CPU firmware releases V2.2 and earlier, the PTO requires the internal functionality of a
high-speed counter (HSC). This means the corresponding HSC cannot be used elsewhere.
The assignment between PTO and HSC is fixed. If PTO1 is activated, it will be connected to
HSC1. If PTO2 is activated, it will be connected to HSC2. You cannot monitor the current
value (for example, in ID1000) when pulses are occurring.
S7-1200 V3.0 and later CPUs do not have this restriction; all HSCs remain available for
program use when pulse outputs are configured in these CPUs.

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10.3 Configuring the axis
Table 10- 5

STEP 7 tools for motion control

Tool

Description

Configuration

Configures the following properties of the "Axis" technology object:
•

Selection of the PTO to be used and configuration of the drive interface

•

Properties of the mechanics and the transmission ratio of the drive (or machine or system)

• Properties for position limits, dynamics, and homing
Save the configuration in the data block of the technology object.
Commissioning

Tests the function of your axis without having to create a user program. When the tool is started,
the control panel will be displayed. The following commands are available on the control panel:
•

Enable and disable axis

•

Move axis in jog mode

•

Position axis in absolute and relative terms

•

Home axis

• Acknowledge errors
The velocity and the acceleration / deceleration can be specified for the motion commands. The
control panel also shows the current axis status.
Diagnostics

Monitors of the current status and error information for the axis and drive.

After you create the technology object for the axis,
you configure the axis by defining the basic
parameters, such as the PTO and the configuration
of the drive interface. You also configure the other
properties of the axis, such as position limits,
dynamics, and homing.

Note
You may have to adapt the values of the input parameters of motion control instructions to
the new dimension unit in the user program.

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10.3 Configuring the axis

Configure the properties for the drive signals, drive
mechanics, and position monitoring (hardware and
software limit switches).

You configure the motion dynamics and the
behavior of the emergency stop command.

You also configure the homing behavior (passive and active).

Use the "Commissioning" control panel to test the functionality independently from your user
program.
Click the "Startup" icon to commission the axis.
The control panel shows the current status of the axis. Not only can you enable and disable
the axis, but you can also test the positioning of the axis (both in absolute and relative terms)
and can specify the velocity, acceleration and deceleration. You can also test the homing
and jogging tasks. The control panel also allows you to acknowledge errors.

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10.4 Configuring the TO_CommandTable_PTO

10.4

Configuring the TO_CommandTable_PTO
You can configure a CommandTable instruction using the Technology objects.

Adding a Technology object
1. In the Project tree, expand the node "Technology Objects" and select "Add new object".
2. Select the "CommandTable" icon (rename if required), and click "OK" to open the
configuration editor for the CommandTable object.

Planning the steps for your application
You can create the desired movement sequence in the "Command Table" configuration
window, and check the result against the graphic view in the trend diagram.
You can select the command types that are to be used for processing the command table.
Up to 32 steps can be entered. The commands are processed in sequence, easily producing
a complex motion profile.

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10.4 Configuring the TO_CommandTable_PTO
Table 10- 6

MC_CommandTable command types

Command type

Description

Empty

The empty serves as a placeholder for any commands to be added. The empty entry is
ignored when the command table is processed

Halt

Pause axis.
Note: The command only takes place after a "Velocity setpoint" command.

Positioning Relative

Positions the axis based upon distance. The command moves the axis by the given
distance and velocity.

Positioning Absolute

Positions the axis based upon location. The command moves the axis to the given
location, using the velocity specified.

Velocity setpoint

Moves the axis at the given velocity.

Wait

Waits until the given period is over. "Wait" does not stop an active traversing motion.

Separator

Adds a "Separator" line above the selected line. The separator line allows more than one
profile to be defined in a single command table.

In the figure below, "Command complete" is used as the transition to the next step. This type
of transition allows your device to decelerate to the start/stop speed and then accelerate
once again at the start of the next step.

① Axis decelerates to the start/stop speed between steps.

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10.4 Configuring the TO_CommandTable_PTO
In the figure below, "Blending motion" is used as the transition to the next step. This type of
transition allows your device to maintain its velocity into the start of the next step, resulting in
a smooth transition for the device from one step to the next. Using blending can shorten the
total time required for a profile to execute completely. Without blending, the example takes
seven seconds to run. With blending, the execution time is reduced by one second to a total
of six seconds.

① Axis continues to move and accelerates or decelerates to the next step velocity, saving time and
mechanical wear.

The operation of your CommandTable is controlled by an MC_CommandTable instruction,
as shown below:

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10.5 Motion control instructions

10.5

Motion control instructions

10.5.1

MC instruction overview
The motion control instructions use an associated technology data block and the dedicated
PTO (pulse train outputs) of the CPU to control the motion on an axis.
● MC_Power (Page 217) enables and disables a motion control axis.
● MC_Reset (Page 221) resets all motion control errors. All motion control errors that can
be acknowledged are acknowledged.
● MC_Home (Page 222) establishes the relationship between the axis control program and
the axis mechanical positioning system.
● MC_Halt (Page 224) cancels all motion processes and causes the axis motion to stop.
The stop position is not defined.
● MC_MoveAbsolute (Page 226) starts motion to an absolute position. The job ends when
the target position is reached.
● MC_MoveRelative (Page 228) starts a positioning motion relative to the start position.
● MC_MoveVelocity (Page 230) causes the axis to travel with the specified speed.
● MC_MoveJog (Page 233) executes jog mode for testing and startup purposes.
● MC_CommandTable (Page 235) runs axis commands as a movement sequence.
● MC_ChangeDynamic (Page 237) changes Dynamics settings for the axis.
● MC_WriteParam (Page 239) writes a select number of parameters to change the
functionality of the axis from the user program.
● MC_ReadParam (Page 241) reads a select number of parameters that indicate the
current position, velocity, and so forth of the axis defined in the Axis input.

CPU firmware levels
If you have an S7-1200 CPU with V4.0 firmware, select the V4.0 version of each motion
instruction.
If you have an S7-1200 CPU with V3.0 or earlier firmware, select the applicable V3.0, V2.0,
or V1.0 version of each motion instruction.

10.5.2

MC_Power (Release/block axis) instruction
Note
If the axis is switched off due to an error, it will be enabled again automatically after the error
has been eliminated and acknowledged. This requires that the Enable input parameter has
retained the value TRUE during this process.

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10.5 Motion control instructions

Table 10- 7

MC_Power instruction

LAD / FBD

SCL

"MC_Power_DB"(
Axis:=_multi_fb_in_,
Enable:=_bool_in_,
StopMode:=_int_in_,
Status=>_bool_out_,
Busy=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

Description
The MC_Power motion control instruction enables
or disables an axis. Before you can enable or
disable the axis, ensure the following conditions:
•

• There is no pending enable-inhibiting error.
The execution of MC_Power cannot be aborted by
a motion control task. Disabling the axis (input
parameter Enable = FALSE) aborts all motion
control tasks for the associated technology object.

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_Power_DB" is the name of the instance DB.

Table 10- 8

The technology object has been configured
correctly.

Parameters for the MC_Power instruction

Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Enable

Bool

•

FALSE (default): All active tasks are aborted according to the
parameterized "StopMode" and the axis is stopped.

•

TRUE: Motion Control attempts to enable the axis.

•

0: Emergency stop: If a request to disable the axis is pending, the
axis brakes at the configured emergency deceleration. The axis is
disabled after reaching standstill.

•

1: Immediate stop: If a request to disable the axis is pending, this
axis is disabled without deceleration. Pulse output is stopped
immediately.

•

2: Emergency stop with jerk control: If a request to disable the axis is
pending, the axis brakes at the configured emergency stop
deceleration. If the jerk control is activated, the configured jerk is
taken into account. The axis is disabled after reaching standstill.

StopMode

Int

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10.5 Motion control instructions

Parameter and type

Data type

Description

Status

Bool

Status of axis enable:

OUT

•

Busy

OUT

Bool

FALSE: The axis is disabled:
–

The axis does not execute motion control tasks and does not
accept any new tasks (exception: MC_Reset task).

–

The axis is not homed.

–

Upon disabling, the status does not change to FALSE until the
axis reaches a standstill.

TRUE: The axis is enabled:
–

The axis is ready to execute motion control tasks.

–

Upon axis enabling, the status does not change to TRUE until
the signal "Drive ready" is pending. If the "Drive ready" drive
interface was not configured in the axis configuration, the status
changes to TRUE immediately.

FALSE: MC_Power is not active.
TRUE: MC_Power is active.

Error

OUT

Bool

FALSE: No error
TRUE: An error has occurred in motion control instruction "MC_Power"
or in the associated technology object. The cause of the error can be
found in parameters "ErrorID" and "ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error""

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID"

①
②

An axis is enabled and then disabled again. After the drive has signaled "Drive ready" back to the CPU, the
successful enable can be read out via "Status_1".
Following an axis enable, an error has occurred that caused the axis to be disabled. The error is eliminated and
acknowledged with "MC_Reset". The axis is then enabled again.

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To enable an axis with configured drive interface, follow these steps:
1. Check the requirements indicated above.
2. Initialize input parameter "StopMode" with the desired value. Set input parameter
"Enable" to TRUE.
The enable output for "Drive enabled" changes to TRUE to enable the power to the drive.
The CPU waits for the "Drive ready" signal of the drive.
When the "Drive ready" signal is available at the configured ready input of the CPU, the
axis becomes enabled. Output parameter "Status" and technology object tag .StatusBits.Enable indicates the value TRUE.
To enable an axis without configured drive interface, follow these steps:
1. Check the requirements indicated above.
2. Initialize input parameter "StopMode" with the desired value. Set input parameter
"Enable" to TRUE. The axis is enabled. Output parameter "Status" and technology object
tag .StatusBits.Enable indicate the value TRUE.
To disable an axis, follow these steps:
1. Bring the axis to a standstill.
You can identify when the axis is at a standstill in technology object tag .StatusBits.StandStill.
2. Set input parameter "Enable" to FALSE after standstill is reached.
3. If output parameters "Busy" and "Status" and technology object tag .StatusBits.Enable indicate the value FALSE, disabling of the axis is complete.

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10.5.3
Table 10- 9

MC_Reset (Confirm error) instruction
MC_Reset instruction

LAD / FBD

SCL

"MC_Reset_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Restart:=_bool_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

Description
Use the MC_Reset instruction to acknowledge
"Operating error with axis stop" and
"Configuration error". The errors that require
acknowledgement can be found in the "List of
ErrorIDs and ErrorInfos" under "Remedy".
Before using the MC_Reset instruction, you
must have eliminated the cause of a pending
configuration error requiring acknowledgement
(for example, by changing an invalid
acceleration value in "Axis" technology object
to a valid value).
As of V3.0 and later, the Restart command
allows the axis configuration to be downloaded
to the work memory in the RUN operating
mode.

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_Reset_DB" is the name of the instance DB.

The MC_Reset task cannot be aborted by any other motion control task. The new MC_Reset
task does not abort any other active motion control tasks.
Table 10- 10 Parameters of the MC_Reset instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Execute

Bool

Start of the task with a positive edge

Restart

Bool

TRUE = Download the axis configuration from the load memory to the
work memory. The command can only be executed when the axis is
disabled.

Done

OUT

Bool

TRUE = Error has been acknowledged.

Busy

OUT

Bool

TRUE = The task is being executed.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task. The
cause of the error can be found in parameters "ErrorID" and
"ErrorInfo".

ErrorID

OUTP

Word

Error ID for parameter "Error""

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID"

FALSE = Acknowledges pending errors

To acknowledge an error with MC_Reset, follow these steps:
1. Check the requirements indicated above.
2. Start the acknowledgement of the error with a rising edge at the Execute input parameter.
3. The error has been acknowledged when Done equals TRUE and the technology object
tag .StatusBits.Error equals FALSE.

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10.5.4

MC_Home (Home axis) instruction

Table 10- 11 MC_Home instruction
LAD / FBD

SCL

"MC_Home_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Position:=_real_in_,
Mode:=_int_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_Home_DB" is the name of the instance DB.

Description
Use the MC_Home instruction to match
the axis coordinates to the real, physical
drive position. Homing is required for
absolute positioning of the axis:
In order to use the MC_Home instruction,
the axis must first be enabled.

The following types of homing are available:
● Direct homing absolute (Mode = 0): The current axis position is set to the value of
parameter "Position".
● Direct homing relative (Mode = 1): The current axis position is offset by the value of
parameter "Position".
● Passive homing (Mode = 2): During passive homing, the MC_Home instruction does not
carry out any homing motion. The traversing motion required for this step must be
implemented by the user via other motion control instructions. When the reference point
switch is detected, the axis is homed.
● Active homing (Mode = 3): The homing procedure is executed automatically.
Table 10- 12 Parameters for the MC_Home instruction
Parameter and type

Data type

Description

Axis

TO_Axis_PTO

Axis technology object

Execute

Bool

Start of the task with a positive edge

Position

Real

•

Mode = 0, 2, and 3 (Absolute position of axis after
completion of the homing operation)

• Mode = 1 (Correction value for the current axis position)
Limit values: -1.0e12 ≤ Position ≤ 1.0e12

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Parameter and type
Mode

Data type

Description

Int

Homing mode
•

0: Direct homing absolute
New axis position is the position value of parameter
"Position".

•

1: Direct homing relative
New axis position is the current axis position + position
value of parameter "Position".

•

2: Passive homing
Homing according to the axis configuration. Following
homing, the value of parameter "Position" is set as the
new axis position.

•

3: Active homing
Reference point approach in accordance with the axis
configuration. Following homing, the value of parameter
"Position" is set as the new axis position.

Done

OUT

Bool

TRUE = Task completed

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another
task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task.
The cause of the error can be found in parameters "ErrorID"
and "ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error""

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID"

Note
Axis homing is lost under the following conditions
• Disabling of axis by the MC_Power instruction
• Switchover between automatic control and manual control
• Upon start of active homing (After successful completion of the homing operation, axis
homing is available again.)
• After power-cycling the CPU
• After CPU restart (RUN-to-STOP or STOP-to-RUN)
To home the axis, follow these steps:
1. Check the requirements indicated above.
2. Initialize the necessary input parameters with values, and start the homing operation with
a rising edge at input parameter "Execute".
3. If output parameter "Done" and technology object tag .StatusBits.HomingDone indicate the value TRUE, homing is complete.

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Table 10- 13 Override response
Mode

Description

0 or 1

The MC_Home task cannot be aborted by any other motion control task. The new MC_Home task does not
abort any active motion control tasks. Position-related motion tasks are resumed after homing according to
the new homing position (value at the Position input parameter).

The MC_Home task can be aborted by the following motion control tasks:
MC_Home task Mode = 2, 3: The new MC_Home task aborts the following active motion control task.
MC_Home task Mode = 2: Position-related motion tasks are resumed after homing according to the new
homing position (value at the Position input parameter).

The MC_Home task can be aborted by the following
motion control tasks:

10.5.5

The new MC_Home task aborts the following active
motion control tasks:

•

MC_Home Mode = 3

•

MC_Halt

•

MC_Halt

•

MC_MoveAbsolute

•

MC_MoveAbsolute

•

MC_MoveRelative

•

MC_MoveRelative

•

MC_MoveVelocity

•

MC_MoveVelocity

•

MC_MoveJog

•

MC_MoveJog

•

MC_Home Mode = 2, 3

MC_Halt (Pause axis) instruction

Table 10- 14 MC_Halt instruction
LAD / FBD

SCL
"MC_Halt_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_Halt_DB" is the name of the instance DB.

Description
Use the MC_Halt instruction to stop all
motion and to bring the axis to a standstill. The stand-still position is not defined.
In order to use the MC_Halt instruction,
the axis must first be enabled.

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Table 10- 15 Parameters for the MC_Halt instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Execute

Bool

Start of the task with a positive edge

Done

OUT

Bool

TRUE = Zero velocity reached

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another
task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task.
The cause of the error can be found in parameters "ErrorID"
and "ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error"

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID"

The following values were configured in the "Dynamics > General" configuration window: Acceleration = 10.0 and
Deceleration = 5.0

①
②

The axis is braked by an MC_Halt task until it comes to a standstill. The axis standstill is signaled via "Done_2".
While an MC_Halt task is braking the axis, this task is aborted by another motion task. The abort is signaled via
"Abort_2".

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Override response

10.5.6

The MC_Halt task can be aborted by the
following motion control tasks:

The new MC_Halt task aborts the following
active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_MoveAbsolute

• MC_MoveRelative

• MC_MoveVelocity

• MC_MoveJog

MC_MoveAbsolute (Position axis absolutely) instruction

Table 10- 16 MC_MoveAbsolute instruction
LAD / FBD

SCL

"MC_MoveAbsolute_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Position:=_real_in_,
Velocity:=_real_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_MoveAbsolute_DB" is the name of the instance DB.

Description
Use the MC_MoveAbsolute
instruction to start a positioning
motion of the axis to an absolute
position.
In order to use the
MC_MoveAbsolute instruction, the
axis must first be enabled and also
must be homed.

Table 10- 17 Parameters for the MC_MoveAbsolute instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Execute

Bool

Start of the task with a positive edge (Default value: False)

Position

Real

Absolute target position (Default value: 0.0)
Limit values: -1.0e12 ≤ Position ≤ 1.0e12

Velocity

Real

Velocity of axis (Default value: 10.0)
This velocity is not always reached because of the configured
acceleration and deceleration and the target position to be
approached.
Limit values: Start/stop velocity ≤ Velocity ≤ maximum velocity

Done

OUT

Bool

TRUE = Absolute target position reached

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Parameter and type

Data type

Description

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task. The
cause of the error can be found in parameters "ErrorID" and
"ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error" (Default value: 0000)

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID" (Default value: 0000)

The following values were configured in the "Dynamics > General" configuration window: Acceleration = 10.0 and
Deceleration = 10.0

①

②

An axis is moved to absolute position 1000.0 with a MC_MoveAbsolute task. When the axis reaches the target
position, this is signaled via "Done_1". When "Done_1" = TRUE, another MC_MoveAbsolute task, with target
position 1500.0, is started. Because of the response times (e.g., cycle time of user program, etc.), the axis comes
to a standstill briefly (see zoomed-in detail). When the axis reaches the new target position, this is signaled via
"Done_2".
An active MC_MoveAbsolute task is aborted by another MC_MoveAbsolute task. The abort is signaled via
"Abort_1". The axis is then moved at the new velocity to the new target position 1500.0. When the new target
position is reached, this is signaled via "Done_2".

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Override response
The MC_MoveAbsolute task can be
aborted by the following motion control
tasks:

The new MC_MoveAbsolute task aborts
the following active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_MoveAbsolute

• MC_MoveRelative

• MC_MoveVelocity

• MC_MoveJog

10.5.7

• MC_Home Mode = 3

MC_MoveRelative (Position axis relatively) instruction

Table 10- 18 MC_MoveRelative instruction
LAD / FBD

SCL

"MC_MoveRelative_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Distance:=_real_in_,
Velocity:=_real_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_MoveRelative_DB " is the name of the instance DB.

Description
Use the MC_MoveRelative
instruction to start a positioning
motion relative to the start position.
In order to use the
MC_MoveRelative instruction, the
axis must first be enabled.

Table 10- 19 Parameters for the MC_MoveRelative instruction
Parameter and type

Data type

Description

TO_Axis_1

Axis technology object

Axis

Execute

Bool

Start of the task with a positive edge (Default value: False)

Distance

Real

Travel distance for the positioning operation (Default value: 0.0)
Limit values: -1.0e12 ≤ Distance ≤ 1.0e12

Velocity

Real

Velocity of axis (Default value: 10.0)
This velocity is not always reached on account of the configured
acceleration and deceleration and the distance to be traveled.
Limit values: Start/stop velocity ≤ Velocity ≤ maximum velocity

Done

OUT

Bool

TRUE = Target position reached
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Parameter and type

Data type

Description

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task. The
cause of the error can be found in parameters "ErrorID" and
"ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error" (Default value: 0000)

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID" (Default value: 0000)

The following values were configured in the "Dynamics > General" configuration window: Acceleration = 10.0 and
Deceleration = 10.0

①

②

The axis is moved by an MC_MoveRelative task by the distance ("Distance") 1000.0. When the axis reaches the
target position, this is signaled via "Done_1". When "Done_1" = TRUE, another MC_MoveRelative task, with travel
distance 500.0, is started. Because of the response times (for example, cycle time of user program), the axis
comes to a standstill briefly (see zoomed-in detail). When the axis reaches the new target position, this is signaled
via "Done_2".
An active MC_MoveRelative task is aborted by another MC_MoveRelative task. The abort is signaled via
"Abort_1". The axis is then moved at the new velocity by the new distance ("Distance") 500.0. When the new target
position is reached, this is signaled via "Done_2".

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Override response

10.5.8

The MC_MoveRelative task can be aborted
by the following motion control tasks:

The new MC_MoveRelative task aborts the
following active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_MoveAbsolute

• MC_MoveRelative

• MC_MoveVelocity

• MC_MoveJog

MC_MoveVelocity (Move axis at predefined velocity) instruction

Table 10- 20 MC_MoveVelocity instruction
LAD / FBD

SCL

"MC_MoveVelocity_DB"(
Axis:=_multi_fb_in_,
Execute:=_bool_in_,
Velocity:=_real_in_,
Direction:=_int_in_,
Current:=_bool_in_,
InVelocity=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_MoveVelocity_DB " is the name of the instance DB.

Description
Use the MC_MoveVelocity
instruction to move the axis
constantly at the specified velocity.
In order to use the
MC_MoveVelocity instruction, the
axis must first be enabled.

Table 10- 21 Parameters for the MC_MoveVelocity instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Execute

Bool

Start of the task with a positive edge (Default value: False)

Velocity

Real

Velocity specification for axis motion (Default value: 10.0)
Limit values: Start/stop velocity ≤ |Velocity| ≤ maximum velocity
(Velocity = 0.0 is allowed)

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Parameter and type
Direction

Current

Data type

Description

Int

Direction specification:

Bool

•

0: Direction of rotation corresponds to the sign of the value in
parameter "Velocity" (Default value)

•

1: Positive direction of rotation (The sign of the value in
parameter "Velocity" is ignored.)

•

2: Negative direction of rotation (The sign of the value in
parameter "Velocity" is ignored.)

Maintain current velocity:
•

FALSE: "Maintain current velocity" is deactivated. The values
of parameters "Velocity" and "Direction" are used. (Default
value)

•

TRUE: "Maintain current velocity" is activated. The values in
parameters "Velocity" and "Direction" are not taken into
account.
When the axis resumes motion at the current velocity, the
"InVelocity" parameter returns the value TRUE.

InVelocity

OUT

Bool

TRUE:
•

If "Current" = FALSE: The velocity specified in parameter
"Velocity" was reached.

•

If "Current" = TRUE: The axis travels at the current velocity at
the start time.

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task. The
cause of the error can be found in parameters "ErrorID" and
"ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error" (Default value: 0000)

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID" (Default value: 0000)

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The following values were configured in the "Dynamics > General" configuration window: Acceleration = 10.0 and
Deceleration = 10.0

①
②

An active MC_MoveVelocity task signals via "InVel_1" that its target velocity has been reached. It is then aborted
by another MC_MoveVelocity task. The abort is signaled via "Abort_1". When the new target velocity 15.0 is
reached, this is signaled via "InVel_2". The axis then continues moving at the new constant velocity.
An active MC_MoveVelocity task is aborted by another MC_MoveVelocity task prior to reaching its target velocity.
The abort is signaled via "Abort_1". When the new target velocity 15.0 is reached, this is signaled via "InVel_2".
The axis then continues moving at the new constant velocity.

Override response
The MC_MoveVelocity task can be aborted
by the following motion control tasks:

The new MC_MoveVelocity task aborts the
following active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_MoveAbsolute

• MC_MoveRelative

• MC_MoveVelocity

• MC_MoveJog

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Note
Behavior with zero set velocity (Velocity = 0.0)
An MC_MoveVelocity task with "Velocity" = 0.0 (such as an MC_Halt task) aborts active
motion tasks and stops the axis with the configured deceleration. When the axis comes to a
standstill, output parameter "InVelocity" indicates TRUE for at least one program cycle.
"Busy" indicates the value TRUE during the deceleration operation and changes to FALSE
together with "InVelocity". If parameter "Execute" = TRUE is set, "InVelocity" and "Busy" are
latched.
When the MC_MoveVelocity task is started, status bit "SpeedCommand" is set in the
technology object. Status bit "ConstantVelocity" is set upon axis standstill. Both bits are
adapted to the new situation when a new motion task is started.

10.5.9

MC_MoveJog (Move axis in jog mode) instruction

Table 10- 22 MC_MoveJog instruction
LAD / FBD

SCL
"MC_MoveJog_DB"(
Axis:=_multi_fb_in_,
JogForward:=_bool_in_,
JogBackward:=_bool_in_,
Velocity:=_real_in_,
InVelocity=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_MoveJog_DB " is the name of the instance DB.

Description
Use the MC_MoveJog instruction to move
the axis constantly at the specified
velocity in jog mode. This instruction is
typically used for testing and
commissioning purposes.
In order to use the MC_MoveJog
instruction, the axis must first be enabled.

Table 10- 23 Parameters for the MC_MoveJog instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

JogForward1

Bool

As long as the parameter is TRUE, the axis moves in the positive
direction at the velocity specified in parameter "Velocity". The sign of
the value in parameter "Velocity" is ignored. (Default value: False)

JogBackward1

Bool

As long as the parameter is TRUE, the axis moves in the negative
direction at the velocity specified in parameter "Velocity". The sign of
the value in parameter "Velocity" is ignored. (Default value: False)

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Parameter and type

Data type

Description

Velocity

Real

Preset velocity for jog mode (Default value: 10.0)

InVelocity

OUT

Bool

TRUE = The velocity specified in parameter "Velocity" was reached.

Busy

OUT

Bool

TRUE = The task is being executed.

CommandAborted

OUT

Bool

TRUE = During execution the task was aborted by another task.

Error

OUT

Bool

TRUE = An error has occurred during execution of the task. The
cause of the error can be found in parameters "ErrorID" and
"ErrorInfo".

ErrorID

OUT

Word

Error ID for parameter "Error" (Default value: 0000)

ErrorInfo

OUT

Word

Error info ID for parameter "ErrorID" (Default value: 0000)

Limit values: Start/stop velocity ≤ |Velocity| ≤ maximum velocity

If both the JogForward and JogBackward parameters are simultaneously TRUE, the axis stops with the configured
deceleration. An error is indicated in parameters "Error", "ErrorID", and "ErrorInfo".

The following values were configured in the "Dynamics > General" configuration window: Acceleration = 10.0 and
Deceleration = 5.0

①
②

The axis is moved in the positive direction in jog mode via "Jog_F". When the target velocity 50.0 is reached, this is
signaled via "InVelo_1". The axis brakes to a standstill again after Jog_F is reset.
The axis is moved in the negative direction in jog mode via "Jog_B". When the target velocity 50.0 is reached, this
is signaled via "InVelo_1". The axis brakes to a standstill again after Jog_B is reset.

Override response
The MC_MoveJog task can be aborted by
the following motion control tasks:

The new MC_MoveJog task aborts the
following active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_MoveAbsolute

• MC_MoveRelative

• MC_MoveVelocity

• MC_MoveJog

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10.5.10

MC_CommandTable (Run axis commans as movement sequence) instruction

Table 10- 24 MC_CommandTable instruction
LAD / FBD

SCL

"MC_CommandTable_DB"(
Axis:=_multi_fb_in_,
CommandTable:=_multi_fb_in_,
Execute:=_bool_in_,
StartIndex:=_uint_in_,
EndIndex:=_uint_in_,
Done=>_bool_out_,
Busy=>_bool_out_,
CommandAborted=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_,
CurrentIndex=>_uint_out_,
Code=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_CommandTable_DB " is the name of the instance DB.

Description
Executes a series of individual
motions for a motor control axis
that can combine into a
movement sequence.
Individual motions are configured
in a technology object command
table for pulse train output
(TO_CommandTable_PTO).

Table 10- 25 Parameters for the MC_CommandTable instruction
Parameter and type

Data type

Initial value

Description

Axis

TO_Axis_1

Axis technology object

Table

TO_CommandTable_1

Command table technology object

Execute

Bool

FALSE

Start job with rising edge

StartIndex

Int

Start command table processing with this step
Limits: 1 ≤ StartIndex ≤ EndIndex

EndIndex

Int

End command table processing with this step
Limits: StartIndex ≤ EndIndex ≤ 32

Done

OUT

Bool

FALSE

MC_CommandTable processing completed
successfully

Busy

OUT

Bool

FALSE

Operation in progress

CommandAborted

OUT

Bool

FALSE

The task was aborted during processing by
another task.

Error

OUT

Bool

FALSE

An error occurred during processing. The cause is
indicated by the parameters ErrorID and ErrorInfo.

ErrorID

OUT

Word

16#0000

Error identifier

ErrorInfo

OUT

Word

16#0000

Error information

Step

OUT

Int

Step currently in process

Code

OUT

Word

16#0000

User defined identifier of the step currently in
process

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You can create the desired movement sequence in the "Command Table" configuration
window and check the result against the graphic view in the trend diagram.

You can select the command types that are to be used for processing the command table.
Up to 32 jobs can be entered. The commands are processed in sequence.
Table 10- 26 MC_CommandTable command types
Command type

Description

Empty

The empty serves as a placeholder for any commands to be added. The empty entry is
ignored when the command table is processed

Halt

Pause axis.
Note: The command only takes place after a "Velocity setpoint" command.

Positioning Relative

Positions the axis based upon distance. The command moves the axis by the given
distance and velocity.

Positioning Absolute

Positions the axis based upon location. The command moves the axis to the given
location, using the velocity specified.

Velocity setpoint

Moves the axis at the given velocity.

Wait

Waits until the given period is over. "Wait" does not stop an active traversing motion.

Separator

Adds a "Separator" line above the selected line. The separator line allows more than one
profile to be defined in a single command table.

Prerequisites for MC_CommandTable execution:
● The technology object TO_Axis_PTO V2.0 must be correctly configured.
● The technology object TO_CommandTable_PTO must be correctly configured.
● The axis must be released.

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Override response
The MC_CommandTable task can be
aborted by the following motion control
tasks:

The new MC_CommandTable task aborts the
following active motion control tasks:

• MC_Home Mode = 3

• MC_Halt

• MC_Halt
• MC_MoveAbsolute
• MC_MoveRelative
• MC_MoveVelocity
• MC_MoveJog
• MC_CommandTable

10.5.11

• MC_Home Mode = 3
• MC_MoveAbsolute
• MC_MoveRelative
• MC_MoveVelocity
• MC_MoveJog
• MC_CommandTable
• The current motion control job with the
launch of the first "Positioning Relative",
"Positioning Absolute", "Velocity setpoint"
or "Halt" command

MC_ChangeDynamic (Change dynamc settings for the axis) instruction

Table 10- 27 MC_ChangeDynamic instruction
LAD / FBD

SCL

"MC_ChangeDynamic_DB"(
Execute:=_bool_in_,
ChangeRampUp:=_bool_in_,
RampUpTime:=_real_in_,
ChangeRampDown:=_bool_in_,
RampDownTime:=_real_in_,
ChangeEmergency:=_bool_in_,
EmergencyRampTime:=_real_in_,
ChangeJerkTime:=_bool_in_,
JerkTime:=_real_in_,
Done=>_bool_out_,
Error=>_bool_out_,
ErrorID=>_word_out_,
ErrorInfo=>_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_ChangeDynamic_DB " is the name of the instance DB.

Description
Changes the dynamic settings of
a motion control axis:
•

Change the ramp-up time
(acceleration) value

•

Change the ramp-down time
(deceleration) value

•

Change the emergency stop
ramp-down time (emergency
stop deceleration) value

•

Change the smoothing time
(jerk) value

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Table 10- 28 Parameters for the MC_ChangeDynamic instruction
Parameter and type

Data type

Description

Axis

TO_Axis_1

Axis technology object

Execute

Bool

Start of the command with a positive edge. Default value:
FALSE

ChangeRampUp

Bool

TRUE = Change ramp-up time in line with input parameter
"RampUpTime". Default value: FALSE

RampUpTime

Real

Time (in seconds) to accelerate from standstill to the configured
maximum velocity without jerk limit. Default value: 5.00
The change will influence the tag .
Config.DynamicDefaults.Acceleration. The effectiveness of the
change is shown in the description of this tag.

ChangeRampDown

Bool

TRUE = Change ramp-down time in line with input parameter
"RampDownTime". Default value: FALSE

RampDownTime

Real

Time (in seconds) to decelerate axis from the configured
maximum velocity to standstill without jerk limiter. Default value:
5.00
The change will influence the tag .
Config.DynamicDefaults.Deceleration. The effectiveness of the
change is shown in the description of this tag.

ChangeEmergency

Bool

TRUE = Change emergency stop ramp-down time in line with
input parameter "EmergencyRampTime" Default value: FALSE

EmergencyRampTime

Real

Time (in seconds) to decelerate the axis from configured
maximum velocity to standstill without jerk limiter in emergency
stop mode. Default value: 2.00
The change will influence the tag .
Config.DynamicDefaults.EmergencyDeceleration. The
effectiveness of the change is shown in the description of this
tag.

ChangeJerkTime

Bool

TRUE = Change smoothing time according to the input
parameter "JerkTime". Default value: FALSE

JerkTime

Real

Smoothing time (in seconds) used for the axis acceleration and
deceleration ramps. Default value: 0.25
The change will influence the tag .
Config.DynamicDefaults.Jerk. The effectiveness of the change is
shown in the description of this tag.

Done

OUT

Bool

TRUE = The changed values have been written to the
technology data block. The description of the tags will show
when the change becomes effective. Default value: FALSE

Error

OUT

Bool

TRUE = An error occurred during execution of the command.
The cause of the error can be found in parameters "ErrorID" and
"ErrorInfo". Default value: FALSE

ErrorID

OUT

Word

Error identifier. Default value: 16#0000

ErrorInfo

Word

Error information. Default value: 16#0000

Prerequisites for MC_ ChangeDynamic execution:
● The technology object TO_Axis_PTO V2.0 must be correctly configured.
● The axis must be released.

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Override response
An MC_ChangeDynamic command cannot be aborted by any other Motion Control
command.
A new MC_ChangeDynamic command does not abort any active Motion Control jobs.
Note
The input parameters "RampUpTime", "RampDownTime", "EmergencyRampTime" and
"RoundingOffTime" can be specified with values that makes the resultant axis parameters
"acceleration", "delay", "emergency stop-delay" and "jerk" outside the permissible limits.
Make sure you keep the MC_ChangeDynamic parameters within the limits of the dynamic
configuration settings for the axis technology object.

10.5.12

MC_WriteParam (write parameters of a technology object) instruction
You use the MC_WriteParam instruction to write a select number of parameters to change
the functionality of the axis from the user program.

Table 10- 29 MC_WriteParam instruction
LAD / FBD

SCL
"MC_WriteParam_DB"(
Parameter:=_variant_in_,
Value:=_variant_in_,
Execute:=_bool_in_,
Done:=_bool_out_,
Error:=_real_out_,
ErrorID:=_word_out_,
ErrorInfo:=_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_WriteParam_DB" is the name of the instance DB.

Description
You use the MC_WriteParam
instruction to write to public
parameters (for example,
acceleration and user DB values).

You can write to the parameters that are public. You cannot write to "MotionStatus" and
"StatusBits". The valid parameters are listed in the table below:
Writeable parameter name

Writeable parameter name

Actor.InverseDirection

DynamicDefaults.Acceleration

Actor.DirectionMode

DynamicDefaults.Deceleration

Actor.DriveParameter.PulsesPerDriveRevolution

DynamicDefaults.Jerk

Sensor[1].ActiveHoming.Mode

DynamicDefaults.EmergencyDeceleration

Sensor[1].ActiveHoming.SideInput

PositionLimitsHW.Active

Sensor[1].ActiveHoming.Offset

PositionLimitsHW.MaxSwitchedLevel

Sensor[1].ActiveHoming.SwitchedLevel

PositionLimitsHW.MinSwitchedLevel

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Writeable parameter name

Sensor[1].PassiveHoming.Mode

PositionLimitsSW.Active

Sensor[1].PassiveHoming.SideInput

PositionLimitsSW.MinPosition

Sensor[1].PassiveHoming.SwitchedLevel

PositionLimitsSW.MaxPosition

Units.LengthUnit

Homing.AutoReversal

Mechanics.LeadScrew

Homing.ApproachDirection

DynamicLimits.MinVelocity

Homing.ApproachVelocity

DynamicLimits.MaxVelocity

Homing.ReferencingVelocity

Table 10- 30 Parameters for the MC_WriteParam instruction
Parameter and type

Data type

Description

PARAMNAME

Variant

Name of parameter where value is written

VALUE

Variant

Value to write to assigned parameter

EXECUTE

Bool

Start the instruction. Default value: FALSE

DONE

OUT

Bool

Value has been written. Default value: FALSE

BUSY

OUT

Bool

If TRUE, the instruction is operating. Default value: FALSE

ERROR

OUT

Real

If TRUE, an error occurred. Default value: FALSE

ERRORID

OUT

Word

ID of the error

ERRORINFO

OUT

Word

Related information to the ERRORID

Table 10- 31 Condition codes for ERRORID and ERRORINFO
ERRORID

ERRORINFO

(W#16#...)

Description

Successful change of an Axis TO-DB parameter

8410[1]

0028[1]

Set an invalid parameter (Axis TO-DB parameter with incorrect length)

8410[1]

0029[1]

Set an invalid parameter (no Axis TO-DB parameter)

8410[1]

002B[1]

Set an Invalid parameter (read-only Axis TO-DB parameter)

8410[1]

002C[1]

Set a valid parameter, but axis is not disabled

Config
Error[2]

Set a valid parameter (public read-only Axis TO-DB parameter) out-of-range

Config
Error[3]

Set a valid parameter (public Axis TO-DB parameter) out-of-range

[1] Error at MC_WriteParam
[2] Error at MC_Power
[3] Error at MC_Power and MC_MoveXXX or MC_CommandTable

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10.5.13

MC_ReadParam instruction (read parameters of a technology object) instruction
You use the MC_ReadParam instruction to read a select number of parameters that indicate
the current position, velocity, and so forth of the axis defined in the Axis input.

Table 10- 32 MC_ReadParam instruction
LAD / FBD

SCL

"MC_ReadParam_DB"(
Enable:=_bool_in_,
Parameter:=_variant_in_,
Value:=_variant_in_out_,
Valid:=_bool_out_,
Busy:=_bool_out_,
Error:=_real_out_,
ErrorID:=_word_out_,
ErrorInfo:=_word_out_);

STEP 7 automatically creates the DB when you insert the instruction.

In the SCL example, "MC_ReadParam_DB " is the name of the instance DB.

Description
You use the MC_ReadParam
instruction to read single status
values, independent of the cycle
control point.

The MC_ReadParam instruction works on an enable behavior. As long as the input "Enable"
is true the instruction reads the specified "Parameter" to the "Value" storage location.
The "MotionStatus" "Position" value updates at each Cycle Control Point (CCP) based upon
the current HSC value.
The "MotionStatus" "Velocity" value is the command velocity at the end of the current
segment (updated ~10ms). The MC_ReadParam can also read this value.
If an error occurs, the instruction switches to an error state that can only be reset by a new
rising edge at the input "Enable".
Table 10- 33 Parameters for the MC_ReadParam instruction
Parameter and type

Data type

Description

ENABLE

Bool

Start the instruction. Default value: FALSE

PARAMETER

Variant

Pointer to the TO-parameter that is to be read

VALID

OUT

Bool

If TRUE, the value has been read. Default value: FALSE

BUSY

OUT

Bool

If TRUE, the instruction is operating. Default value: FALSE

ERROR

OUT

Real

If TRUE, an error occurred. Default value: FALSE

ERRORID

OUT

Word

ID of the error. Default value: 0

ERRORINFO

OUT

Word

Related information to the ERRORID. Default value: 0

VALUE

INOUT Variant

Pointer to the location where the read value is stored

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Table 10- 34 Condition codes for ERRORID and ERRORINFO
ERRORID

ERRORINFO

Description

(W#16#...)

Successful read of a parameter

8410

0028

Invalid parameter (incorrect length)

8410

0029

Invalid parameter (no TO-DB)

8410

0030

Invalid parameter (not readable)

8411

0032

Invalid parameter (wrong value)

TO parameters
The axis "MotionStatus" consists of four values. You will want to monitor changes in these
values, which can be read while the program is running:
Variable name

Data type

Readable through
MC_ReadParam

MotionStatus:

Structure

•

Position

REAL

Yes

•

Velocity

REAL

Yes

•

Distance

REAL

Yes

•

TargetPosition

REAL

Yes

10.6

Operation of motion control for S7-1200

10.6.1

CPU outputs used for motion control
The CPU provides four pulse output generators. Each pulse output generator provides one
pulse output and one direction output for controlling a stepper motor drive or a servo motor
drive with pulse interface. The pulse output provides the drive with the pulses required for
motor motion. The direction output controls the travel direction of the drive.
The PTO output generates a square wave output of variable frequency. Pulse generation is
controlled by configuration and execution information supplied through H/W configuration
and/or SFCs/SFBs.
Based upon the user’s selection while the CPU is in RUN mode, either the values stored in
the image register or the pulse generator outputs drive the digital outputs. In STOP mode,
the PTO generator does not control the outputs.
Onboard CPU outputs and outputs of a signal board can be used as pulse and direction
outputs. You select between onboard CPU outputs and outputs of the signal board during
device configuration under Pulse generators (PTO/PWM) on the "Properties" tab. Only PTO
(Pulse Train Output) applies to motion control.

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The table below shows the default I/O assignments; however, the four pulse generators can
be configured to any digital output.
Note
Pulse-train outputs cannot be used by other instructions in the user program.
When you configure the outputs of the CPU or signal board as pulse generators (for use with
the PWM or motion control instructions), the corresponding output addresses no longer
control the outputs. If your user program writes a value to an output used as a pulse
generator, the CPU does not write that value to the physical output.
Note
PTO direction outputs can be freed for use elsewhere in your program.
Each PTO requires the assignment of two outputs: one as a pulse output and one as a
direction output. You can use just the pulse output and not the direction output. You can then
free the direction output for other purposes in your user program. The output cannot be used
for both the PTO direction output and in the user program, simultaneously.

Table 10- 35 Default address assignments of the pulse and direction outputs
Usage of outputs for motion control
Pulse

Direction

Built-in I/O

Q0.0

Q0.1

SB I/O

Q4.0

Q4.1

Built-in I/O

Q0.2

Q0.3

SB I/O

Q4.2

Q4.3

Built-in I/O

Q0.41

Q0.51

SB I/O

Q4.0

Q4.1

Built-in I/O

Q0.62

Q0.72

SB I/O

Q4.2

Q4.3

PTO1

PTO2

PTO3

PTO4

The CPU 1211C does not have outputs Q0.4, Q0.5, Q0.6, or Q0.7. Therefore, these outputs
cannot be used in the CPU 1211C.

The CPU 1212C does not have outputs Q0.6 or Q0.7. Therefore, these outputs cannot be used in
the CPU 1212C.

This table applies to the CPU 1211C, CPU 1212C, CPU 1214C, CPU 1215C, and CPU 1217C
PTO functions.

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Drive interface
For motion control, you can optionally configure a drive interface for "Drive enabled" and
"Drive ready". When using the drive interface, the digital output for the drive enable and the
digital input for "drive ready" can be freely selected.
Note
The firmware will take control through the corresponding pulse and direction outputs if the
PTO (Pulse Train Output) has been selected and assigned to an axis.
With this takeover of the control function, the connection between the process image and I/O
output is also disconnected. While the user has the possibility of writing the process image of
pulse and direction outputs via the user program or watch table, this is never transferred to
the I/O output. Accordingly, it is also not possible to monitor the I/O output via the user
program or watch table. The information read merely reflects the value of the process image
and does not match the actual status of the I/O output in any respect.
For all other CPU outputs that are not used permanently by the CPU firmware, the status of
the I/O output can be controlled or monitored via the process image, as usual.

10.6.2

Hardware and software limit switches for motion control
Use the hardware and software limit switches to limit the "allowed travel range" and the
"working range" of your axis.

①
②
③

Mechanical stop

Allowed travel range for the axis

Lower and upper hardware limits

Working range of the axis

Lower and upper software limits

Distance

Hardware and software limit switches must be activated prior to use in the configuration or in
the user program. Software limit switches are only active after homing the axis.

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Hardware limit switches
Hardware limit switches determine the maximum travel range of the axis. Hardware limit
switches are physical switching elements that must be connected to interrupt-capable inputs
of the CPU. Use only hardware limit switches that remain permanently switched after being
approached. This switching status may only be revoked after a return to the allowed travel
range.
Table 10- 36 Available inputs for hardware limits
Description

RPS

LIM-

Built-in I/O

I0.0 - I1.5

SB I/O

I4.0 - I4.3

LIM+

When the hardware limit switches are approached, the axis brakes to a standstill at the
configured emergency deceleration. The specified emergency deceleration must be
sufficient to reliably stop the axis before the mechanical stop. The following diagram
presents the behavior of the axis after it approaches the hardware limit switches.

①
②

The axis brakes to a standstill at the configured emergency deceleration.

[Velocity]

Allowed travel range

Distance

Mechanical stop

Lower hardware limit switch

Upper hardware limit switch

Range in which the hardware limit switches signal the stats "approached".

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WARNING
Risks with changes to filter time for digital input channel
If the filter time for a digital input channel is changed from a previous setting, a new "0"
level input value may need to be presented for up to 20.0 ms accumulated duration before
the filter becomes fully responsive to new inputs. During this time, short "0" pulse events of
duration less than 20.0 ms may not be detected or counted.
This changing of filter times can result in unexpected machine or process operation, which
may cause death or serious injury to personnel, and/or damage to equipment.
To ensure that a new filter time goes immediately into effect, a power cycle of the CPU
must be applied.

Software limit switches
Software limit switches limit the "working range" of the axis. They should fall inside the
hardware limit switches relative to the travel range. Because the positions of the software
limit switches can be set flexibly, the working range of the axis can be restricted on an
individual basis depending on the current traversing profile. In contrast to hardware limit
switches, software limit switches are implemented exclusively by means of the software and
do not require their own switching elements.
If software limit switches are activated, an active motion is stopped at the position of the
software limit switch. The axis is braked at the configured deceleration. The following
diagram presents the behavior of the axis until it reaches the software limit switches.

①

The axis brakes to a standstill at the configured deceleration.

[Velocity]

Working range

Distance

Lower software limit switch

Upper software limit switch

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Use additional hardware limit switches if a mechanical endstop is located after the software
limit switches and there is a risk of mechanical damage.

Additional information
Your user program can override the hardware or software position limits by enabling or
disabling both hardware and software limits functionality. The selection is made from the
Axis DB.
● To enable or disable the hardware limit functionality, access the "Active" tag (Bool) in the
DB path "/Config/PositonLimits_HW". The state of the "Active" tag enables
or disables the use of hardware position limits.
● To enable or disable software position limit functionality, access "Active" tag (Bool) in the
DB path "/Config/Position Limits_SW". The state of this "Active" tag enables
or disables the software position limits.
You can also modify the software position limits with your user program (for example, to add
flexibility for machine setup or to shorten machine change-over time). Your user program can
write new values to the " MinPosition " and " MaxPosition " tags (engineering units in Real
format) in the DB "/Config/PositionLimits_SW".

10.6.3

Homing

10.6.3.1

Homing the axis
Homing refers to the matching of the axis coordinates to the real, physical drive position. (If
the drive is currently at position x, the axis will be adjusted to be in position x.) For positioncontrolled axes, the entries and displays for the position refer exactly to these axis
coordinates.
Note
The agreement between the axis coordinates and the real situation is extremely important.
This step is necessary to ensure that the absolute target position of the axis is also achieved
exactly with the drive.
The MC_Home instruction initiates the homing of the axis.

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There are 4 different homing functions. The first two functions allow the user to set the
current position of the axis and the second two position the axis with respect to a Home
reference Sensor.
● Mode 0 - Direct Referencing Absolute: When executed this mode tells the axis exactly
where it is. It sets the internal position variable to the value of the Position input of the
Homing instruction. This is used for machine calibration and setup.
The axis position is set regardless of the reference point switch. Active traversing motions
are not aborted. The value of the Position input parameter of the MC_Home instruction is
set immediately as the reference point of the axis. To assign the reference point to an
exact mechanical position, the axis must be at a standstill at this position at the time of
the homing operation.
● Mode 1 - Direct Referencing Relative: When executed this mode uses the internal
position variable and adds the value of the Position input on the Homing instruction to it.
This is typically used to account for machine offset.
The axis position is set regardless of the reference point switch. Active traversing motions
are not aborted. The following statement applies to the axis position after homing: New
axis position = current axis position + value of the Position parameter of the MC_Home
instruction.
● Mode 2 - Passive Referencing: When the axis is moving and passes the Reference Point
Switch the current position is set as the home position. This feature will help account for
normal machine wear and gear backlash and prevent the need for manual compensation
for wear. The Position input on the Homing instruction, as before, adds to the location
indicated by the Reference Point Switch allowing easy offset of the Home position.
During passive homing, the MC_Home instruction does not carry out any homing motion.
The traversing motion required for this step must be implemented by the user via other
motion control instructions. When the reference point switch is detected, the axis is
homed according to the configuration. Active traversing motions are not aborted upon
start of passive homing.
● Mode 3 - Active Referencing: This mode is the most precise method of Homing the Axis.
The initial direction and velocity of movement is configured in the Technology Object
Configuration Extended Parameters-Homing. This is dependent upon machine
configuration. There is also the ability to determine if the leading edge or falling edge of
the Reference Point Switch signal is the Home position. Virtually all sensors have an
active range and if the Steady State On position was used as the Home signal then there
would be a possibility for error in the Homing position since the On signal active range
would cover a range of distance. By using either the leading or falling edge of that signal
a much more precise Home position results. As with all other modes the value of the
Position input on the Homing instruction is added to the Hardware referenced position.
In active homing mode, the MC_Home instruction performs the required reference point
approach. When the reference point switch is detected, the axis is homed according to
the configuration. Active traversing motions are aborted.
Modes 0 and 1 do not require that the axis be moved at all. They are typically used in setup
and calibration. Modes 2 and 3 require that the axis move and pass a sensor that is
configured in the "Axis" technology object as the Reference Point Switch. The reference
point can be placed in the work area of the axis or outside of the normal work area but within
movement range.

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10.6.3.2

Configuration of homing parameters
Configure the parameters for active and passive homing in the "Homing" configuration
window. The homing method is set using the "Mode" input parameter of the motion control
instruction. Here, Mode = 2 means passive homing and Mode = 3 means active homing.
Note
Use one of the following measures to ensure that the machine does not travel to a
mechanical endstop in the event of a direction reversal:
• Keep the approach velocity low
• Increase the configured acceleration/deceleration
• Increase the distance between hardware limit switch and mechanical stop

Table 10- 37 Configuration parameters for homing the axis
Parameter

Description

Input reference point switch

Select the digital input for the reference point switch from the drop-down list box. The
input must be interrupt-capable. The onboard CPU inputs and inputs of an inserted
signal board can be selected as inputs for the reference point switch.

(Active and passive homing)

The default filter time for the digital inputs is 6.4 ms. When the digital inputs are used
as a reference point switch, this can result in undesired decelerations and thus
inaccuracies. Depending on the reduced velocity and extent of the reference point
switch, the reference point may not be detected. The filter time can be set under
"Input filter" in the device configuration of the digital inputs.
The specified filter time must be less than the duration of the input signal at the
reference point switch.
Auto reverse after reaching the
hardware limit switches
(Active homing only)

Activate the check box to use the hardware limit switch as a reversing cam for the
reference point approach. The hardware limit switches must be configured and
activated for direction reversal.
If the hardware limit switch is reached during active homing, the axis brakes at the
configured deceleration (not with the emergency deceleration) and reverses direction.
The reference point switch is then sensed in reverse direction.
If the direction reversal is not active and the axis reaches the hardware limit switch
during active homing, the reference point approach is aborted with an error and the
axis is braked at the emergency deceleration.

Approach direction
(Active and passive homing)

With the direction selection, you determine the "approach direction" used during
active homing to search for the reference point switch, as well as the homing
direction. The homing direction specifies the travel direction the axis uses to
approach the configured side of the reference point switch to carry out the homing
operation.

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Parameter

Description

Reference point switch

•

Active homing: Select whether the axis is to be referenced on the left or right side
of the reference point switch. Depending on the start position of the axis and the
configuration of the homing parameters, the reference point approach sequence
can differ from the diagram in the configuration window.

•

Passive homing: With passive homing, the traversing motions for purposes of
homing must be implemented by the user via motion commands. The side of the
reference point switch on which homing occurs depends on the following factors:

(Active and passive homing)

Approach velocity
(Active homing only)

Reduced velocity
(Active homing only)

Home position offset
(Active homing only)

–

"Approach direction" configuration

–

"Reference point switch" configuration

–

Current travel direction during passive homing

Specify the velocity at which the reference point switch is to be searched for during
the reference point approach.
Limit values (independent of the selected user unit):
Start/stop velocity ≤ approach velocity ≤ maximum velocity
Specify the velocity at which the axis approaches the reference point switch for
homing.
Limit values (independent of the selected user unit):
Start/stop velocity ≤ reduced velocity ≤ maximum velocity
If the desired reference position deviates from the position of the reference point
switch, the home position offset can be specified in this field.
If the value does not equal 0, the axis executes the following actions following
homing at the reference point switch:
1. Move the axis at reduced velocity by the value of the home position offset.
2. When the position of the home position offset is reached, the axis position is set
to the absolute reference position. The absolute reference position is specified via
parameter "Position" of motion control instruction "MC_Home".
Limit values (independent of the selected user unit):
-1.0e12 ≤ home position offset ≤ 1.0e12

Table 10- 38 Factors that affect homing
Influencing factors:
Configuration

Configuration

Approach direction

Reference point switch

Positive

"Left (negative) side"

Positive

"Right (positive) side"

Negative

"Left (negative) side"

Negative

"Right (positive) side"

Result:
Current travel direction

Homing on
Reference point switch

Positive direction

Left

Negative direction

Right

Positive direction

Right

Negative direction

Left

Positive direction

Right

Negative direction

Left

Positive direction

Left

Negative direction

Right

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10.6 Operation of motion control for S7-1200

10.6.3.3

Sequence for active homing
You start active homing with motion control instruction "MC_Home" (input parameter
Mode = 3). Input parameter "Position" specifies the absolute reference point coordinates in
this case. Alternatively, you can start active homing on the control panel for test purposes.
The following diagram shows an example of a characteristic curve for an active reference
point approach with the following configuration parameters:
● "Approach direction" = "Positive approach direction"
● "Reference point switch" = "Right (positive) side"
● Value of "home position offset" > 0

Table 10- 39 Velocity characteristics of MC homing
Operation

Notes
A

Approach velocity

Reduced velocity

Home position coordinate

Home position offset

①

Search phase (blue curve segment): When active homing starts, the axis accelerates to the configured "approach
velocity" and searches at this velocity for the reference point switch.

②

Reference point approach (red curve section): When the reference point switch is detected, the axis in this example
brakes and reverses, to be homed on the configured side of the reference point switch at the configured "reduced
velocity".

③

Travel to reference point position (green curve segment): After homing at the reference point switch, the axis travels
to the "Reference point coordinates" at the "reduced velocity". On reaching the "Reference point coordinates", the
axis is stopped at the position value that was specified in the Position input parameter of the MC_Home instruction".

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Note
If the homing search does not function as you expected, check the inputs assigned to the
hardware limits or to the reference point. These inputs may have had their edge interrupts
disabled in device configuration.
Examine the configuration data for the axis technology object of concern to see which inputs
(if any) are assigned for "HW Low Limit Switch Input", "HW High Limit Switch Input", and
"Input reference point switch". Then open the Device configuration for the CPU and examine
each of the assigned inputs. Verify the "Enable rising edge detection" and "Enable falling
edge detection" are both selected. If these properties are not selected, delete the specified
inputs in the axis configuration and select them again.

10.7

Commissioning

"Status and error bits" diagnostic function
Use the "Status and error bits" diagnostic function to monitor the most important status and
error messages for the axis. The diagnostic function display is available in online mode in
"Manual control" mode and in "Automatic control" when the axis is active.
Table 10- 40 Status of the axis
Status
Enabled

Description
The axis is enabled and ready to be controlled via motion control tasks.
(Tag of technology object: .StatusBits.Enable)

Homed

The axis is homed and is capable of executing absolute positioning tasks of motion control
instruction "MC_MoveAbsolute". The axis does not have to be homed for relative homing. Special
situations:
•

During active homing, the status is FALSE.

• If a homed axis undergoes passive homing, the status is set to TRUE during passive homing.
(Tag of technology object: .StatusBits.HomingDone)
Error

An error has occurred in the "Axis" technology object. More information about the error is available
in automatic control at the ErrorID and ErrorInfo parameters of the motion control instructions. In
manual mode, the "Last error" field of the control panel displays detailed information about the
cause of error.
(Tag of technology object: .StatusBits.Error)

Control panel active

The "Manual control" mode was enabled in the control panel. The control panel has control priority
over the "Axis" technology object. The axis cannot be controlled from the user program.
(Tag of technology object: .StatusBits.ControlPanelActive)

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Table 10- 41 Drive status
Status
Drive ready

Description
The drive is ready for operation.
(Tag of technology object: .StatusBits.DriveReady)

Error

The drive has reported an error after failure of its ready signal.
(Tag of technology object: .ErrorBits.DriveFault)

Table 10- 42 Status of the axis motion
Status

Description

Standstill

The axis is at a standstill.
(Tag of technology object: .StatusBits.StandStill)

Accelerating

The axis accelerates.
(Tag of technology object: .StatusBits.Acceleration)

Constant velocity

The axis travels at constant velocity.
(Tag of technology object: .StatusBits.ConstantVelocity)

Decelerating

The axis decelerates (slows down).
(Tag of technology object: .StatusBits.Deceleration)

Table 10- 43 Status of the motion mode
Status

Description

Positioning

The axis executes a positioning task of motion control instruction "MC_MoveAbsolute" or
"MC_MoveRelative" or of the control panel.
(Tag of technology object: .StatusBits.PositioningCommand)

Speed Command

The axis executes a task at set speed of motion control instruction "MC_MoveVelocity" or
"MC_MoveJog" or of the control panel.
(Tag of technology object: .StatusBits.SpeedCommand)

Homing

The axis executes a homing task of motion control instruction "MC_Home" or the control
panel.
(Tag of technology object: .StatusBits.Homing)

Table 10- 44 Error bits
Error

Description

Min software limit reached

The lower software limit switch has been reached.
(Tag of technology object: .ErrorBits.SwLimitMinReached)

Min software limit exceeded

The lower software limit switch has been exceeded.
(Tag of technology object: .ErrorBits.SwLimitMinExceeded)

Max software limit reached

The upper software limit switch has been reached.
(Tag of technology object: .ErrorBits.SwLimitMaxReached)

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Error

Description

Max software limit exceeded

The upper software limit switch has been exceeded.
(Tag of technology object: .ErrorBits.SwLimitMaxExceeded)

Negative hardware limit

The lower hardware limit switch has been approached.
(Tag of technology object: .ErrorBits.HwLimitMin)

Positive hardware limit

The upper hardware limit switch has been approached.
(Tag of technology object: .ErrorBits.HwLimitMax)

PTO already used

A second axis is using the same PTO and is enabled with "MC_Power".
(Tag of technology object: .ErrorBits.HwUsed)

Configuration error

The "Axis" technology object was incorrectly configured or editable configuration data
were modified incorrectly during runtime of the user program.
(Tag of technology object: .ErrorBits.ConfigFault)

General Error

An internal error has occurred.
(Tag of technology object: .ErrorBits.SystemFault)

"Motion status" diagnostic function
Use the "Motion status" diagnostic function to monitor the motion status of the axis. The
diagnostic function display is available in online mode in "Manual control" mode and in
"Automatic control" when the axis is active.
Table 10- 45 Motion status
Status

Description

Target position

The "Target position" field indicates the current target position of an active positioning task of
motion control instruction "MC_MoveAbsolute" or "MC_MoveRelative" or of the control panel.
The value of the "Target position" is only valid during execution of a positioning task.
(Tag of technology object: .MotionStatus.TargetPosition)

Current position

The "Current position" field indicates the current axis position. If the axis is not homed, the
value indicates the position value relative to the enable position of the axis.
(Tag of technology object: .MotionStatus.Position)

Current velocity

The "Current velocity" field indicates the actual axis velocity.
(Tag of technology object: .MotionStatus.Velocity)

Table 10- 46 Dynamic limits
Dynamic limit

Description

Velocity

The "Velocity" field indicates the configured maximum velocity of the axis.
(Tag of technology object: .Config.DynamicLimits.MaxVelocity)

Acceleration

The "Acceleration" field indicates the currently configured acceleration of the axis.
(Tag of technology object: .Config.DynamicDefaults.Acceleration)

Deceleration

The "Deceleration" field indicates the currently configured deceleration of the axis.
(Tag of technology object: .Config.DynamicDefaults.Deceleration)

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Motion start value control
You can edit the actual values of the Motion configuration parameters so that the behavior of
the process can be optimized in online mode.
Open the "Technology objects" for your motion control and its "Configuration" object. To
access the start value control, click the "eyeglasses icon" in the upper left corner of the
dialog:

You can now change the value of any of your motion control configuration parameters as
shown in the figure below.
You can compare the actual value to the project (offline) start value and the PLC (online)
start value of each parameter. This is necessary to compare online/offline differences of the
Technology object data block (TO-DB) and to be informed about the values that will be used
as current values on the next Stop-to-Start transition of the PLC. In addition, a compare icon
gives a visual indication to help easily identify online/offline differences.

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The figure above shows the Motion parameter screen with compare icons showing which
values are different between online and offline projects. A green icon indicates that the
values are the same; a blue/orange icon indicates that the values are different.
Additionally, click the parameter button with the downward arrow to open a small window
that shows the project (offline) start value and the PLC (online) start value of each
parameter.

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11.1

Going online and connecting to a CPU
An online connection between the programming device and CPU is required for loading
programs and project engineering data as well as for activities such as the following:
● Testing user programs
● Displaying and changing the operating mode of the CPU (Page 258)
● Displaying and setting the date and time of day of the CPU (Page 267)
● Displaying the module information
● Comparing and synchronizing (Page 266) offline to online program blocks
● Uploading and downloading program blocks
● Displaying diagnostics and the diagnostics buffer (Page 267)
● Using a watch table (Page 260) to test the user program by monitoring and modifying
values
● Using a force table to force values in the CPU (Page 261)
To establish an online connection to a configured CPU, click
the CPU from the Project Navigation tree and click the "Go
online" button from the Project View:
If this is the first time to go
online with this CPU, you
must select the type of PG/PC
interface and the specific
PG/PC interface from the Go
Online dialog before
establishing an online
connection to a CPU found on
that interface.

Your programming device is now connected to the CPU. The orange color frames indicate
an online connection. You can now use the Online & diagnostics tools from the Project tree
and the Online tools task card.

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11.2 Interacting with the online CPU

11.2

Interacting with the online CPU
The "Online tools" task card in the project view displays an operator panel that shows the
operating mode of the online CPU. The operator panel also allows you to change the
operating mode of the online CPU. Use the button on the operator panel to change the
operating mode (STOP or RUN). The operator panel also provides an MRES button for
resetting the memory.
The color of the RUN/STOP indicator shows the current operating
mode of the CPU: yellow indicates STOP mode, and green indicates
RUN mode.

To use the operator panel, you must establish an online connection between STEP 7 and
the CPU. After you select the CPU in the device configuration or display a code block in the
online CPU, you can display the operator panel from the "Online tools" task card.

You can monitor the cycle time of an online CPU.

You can also view the memory usage of the CPU.

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11.3 Going online to monitor the values in the CPU

11.3

Going online to monitor the values in the CPU
To monitor the tags, you must have an online connection to the CPU. Simply click the "Go
online" button in the toolbar.

When you have connected to the CPU, STEP 7 turns the headers of
the work areas orange.
The project tree displays a comparison of the offline project and the
online CPU. A green circle means that the CPU and the project are
synchronized, meaning that both have the same configuration and
user program.
Tag tables show the tags. Watch tables can also show the tags, as
well as direct addresses.

To monitor the execution of the user program and to display the values of the tags,
click the "Monitor all" button in the toolbar.

The "Monitor value" field shows the value for each tag.

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11.4 Displaying status of the user program is easy

11.4

Displaying status of the user program is easy
You can monitor the status of the tags in the LAD and FBD program editors. Use the editor
bar to display the LAD editor. The editor bar allows you to change the view between the
open editors without having to open or close the editors.
In the toolbar of the program editor, click the "Monitoring on/off" button to display the status
of your user program.

The network in the program editor displays power flow in green.
You can also right-click on the instruction or parameter to modify the value for the instruction.

11.5

Using a watch table for monitoring the CPU
A watch table allows you to monitor or modify data points while the CPU executes your user
program. These data points can be inputs (I), outputs (Q), M memory, a DB, or peripheral
inputs (such as "On:P" or "I 3.4:P"). You cannot accurately monitor the physical outputs
(such as Q0.0:P) because the monitor function can only display the last value written from Q
memory and does not read the actual value from the physical outputs.
The monitoring function does not change the program sequence. It presents you with
information about the program sequence and the data of the program in the CPU. You can
also use the "Modify value" function to test the execution of your user program.

Note
The digital I/O points used by the high-speed counter (HSC), pulse-width modulation (PWM),
and pulse-train output (PTO) devices are assigned during device configuration. When digital
I/O point addresses are assigned to these devices, the values of the assigned I/O point
addresses cannot be modified by the "Force" function of the watch table.
With a watch table, you can monitor or modify the values of the individual tags, choosing
from the following options:
● At the beginning or the end of the scan cycle
● When the CPU changes to STOP mode
● "Permanently" (with the value not being reset after a STOP to RUN transition)

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11.6 Using the force table

To create a watch table:
1. Double-click "Add new watch table" to open a new
watch table.
2. Enter the tag name to add a tag to the watch
table.

To monitor the tags, you must have an online connection to the CPU. The following options
are available for modifying tags:
● "Modify now" immediately changes the value for the selected addresses for one scan
cycle.
● "Modify with trigger" changes the values for the selected addresses.
This function does not provide feedback to indicate that the selected addresses were
actually modified. If feedback of the change is required, use the "Modify now" function.
● "Enable peripheral outputs" allows you to turn on the peripheral outputs when the CPU is
in STOP mode. This feature is useful for testing the wiring of the output modules.
The various functions can be selected using the buttons at the top of a watch table. Enter the
tag name to monitor and select a display format from the dropdown selection. With an online
connection to the CPU, clicking the "Monitor" button displays the actual value of the data
point in the "Monitor value" field.

11.6

Using the force table
A force table provides a "force" function that overwrites the value for an input or output point
to a specified value for the peripheral input or peripheral output address. The CPU applies
this forced value to the input process image prior to the execution of the user program and to
the output process image before the outputs are written to the modules.

Note
The force values are stored in the CPU and not in the force table.
You cannot force an input (or "I" address) or an output (or "Q" address). However, you can
force a peripheral input or peripheral output. The force table automatically appends a ":P" to
the address (for example: "On":P or "Run":P).

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11.6 Using the force table

In the "Force value" cell, enter the value for the input or output to be forced. You can then
use the check box in the "Force" column to enable forcing of the input or output.
Use the "Start or replace forcing" button to force the value of the tags in the force
table. Click the "Stop forcing" button to reset the value of the tags.
In the force table, you can monitor the status of the forced value for an input. However, you
cannot monitor the forced value of an output.
You can also view the status of the forced value in the program editor.

Note
When an input or output is forced in a force table, the force actions become part of the
project configuration. If you close STEP 7, the forced elements remain active in the CPU
program until they are cleared. To clear these forced elements, you must use STEP 7 to
connect with the online CPU and then use the force table to turn off or stop the force function
for those elements.
The CPU allows you to force input and output point(s) by specifying the physical input or
output address (I_:P or Q_:P) in the force table and then starting the force function.
In the program, reads of physical inputs are overwritten by the forced value. The program
uses the forced value in processing. When the program writes a physical output, the output
value is overwritten by the force value. The forced value appears at the physical output and
is used by the process.
When an input or output is forced in the force table, the force actions become part of the
user program. Even though the programming software has been closed, the force selections
remain active in the operating CPU program until they are cleared by going online with the
programming software and stopping the force function. Programs with forced points loaded
on another CPU from a memory card will continue to force the points selected in the
program.

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11.6 Using the force table
If the CPU is executing the user program from a write-protected memory card, you cannot
initiate or change the forcing of I/O from a watch table because you cannot override the
values in the write-protected user program. Any attempt to force the write-protected values
generates an error. If you use a memory card to transfer a user program, any forced
elements on that memory card will be transferred to the CPU.
Note
Digital I/O points assigned to HSC, PWM, and PTO cannot be forced
The digital I/O points used by the high-speed counter (HSC), pulse-width modulation (PWM),
and pulse-train output (PTO) devices are assigned during device configuration. When digital
I/O point addresses are assigned to these devices, the values of the assigned I/O point
addresses cannot be modified by the force function of the force table.

Startup

RUN

The clearing of the I memory area is not
affected by the Force function.

①

The initialization of the outputs values is
not affected by the Force function.

②

During the execution of the startup OBs,
the CPU applies the force value when
the user program accesses the physical
input.

③

The storing of interrupt events into the
queue is not affected.

④

The enabling of the writing to the
outputs is not affected.

⑤

While writing Q memory to the physical
outputs, the CPU applies the force value as
the outputs are updated.
When reading the physical inputs, the CPU
applies the force values just prior to copying
the inputs into I memory.
During the execution of the user program
(program cycle OBs), the CPU applies the
force value when the user program accesses
the physical input or writes the physical
output.
Handling of communication requests and selftest diagnostics are not affected by the Force
function.
The processing of interrupts during any part of
the scan cycle is not affected.

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11.7 Capturing the online values of a DB to reset the start values

11.7

Capturing the online values of a DB to reset the start values
You can capture the current values being monitored in an online CPU to become the start
values for a global DB.
● You must have an online connection to the CPU.
● The CPU must be in RUN mode.
● You must have opened the DB in STEP 7.
Use the "Show a snapshot of the monitored values" button to capture the current
values of the selected tags in the DB. You can then copy these values into the "Start
value" column of the DB.
1. In the DB editor, click the "Monitor all tags" button. The "Monitor value" column displays
the current data values.
2. Click the "Show a snapshot of the monitored values" button to display the current values
in the "Snapshot" column.
3. Click the "Monitor all" button to stop monitoring the data in the CPU.
4. Copy a value in the "Snapshot" column for a tag.
– Select a value to be copied.
– Right-click the selected value to display the context menu.
– Select the "Copy" command.
5. Paste the copied value into the corresponding "Start value" column for the tag. (Rightclick the cell and select "Paste" from the context menu.)
6. Save the project to configure the copied values as the new start values for the DB.
7. Compile and download the DB to the CPU. The DB uses the new start values after the
CPU goes to RUN mode.
Note
The values that are shown in the "Monitor value" column are always copied from the
CPU. STEP 7 does not check whether all values come from the same scan cycle of the
CPU.

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11.8 Copying elements of the project

11.8

Copying elements of the project
You can also copy the program blocks from an online CPU or a memory card attached to
your programming device.
Prepare the offline project for the copied program blocks:
1. Add a CPU device that matches the online CPU.
2. Expand the CPU node once so that the "Program
blocks" folder is visible.

To upload the program blocks from the online CPU to the
offline project, follow these steps:
1. Click the "Program blocks" folder in the offline project.
2. Click the "Go online" button.
3. Click the "Upload" button.
4. Confirm your decision from the Upload dialog.
As an alternative to the previous method, follow these
steps:
1. From the project navigator, expand the node for
"Online access" to select the program blocks in the
online CPU:
2. Expand the node for the network, and double click
"Update accessible devices".
3. Expand the node for the CPU.
4. Drag the "Program blocks" folder from the online CPU
and drop the folder into the "Program blocks" folder of
your offline project.
5. In the "Upload preview" dialog, select the box for
"Continue", and then click the "Upload from device"
button.
When the upload is complete, all of the program blocks,
technology blocks, and tags will be displayed in the offline
area.

Note
You can copy the program blocks from the online CPU to an existing program. The
"Program-blocks" folder of the offline project does not have to be empty. However, the
existing program will be deleted and replaced by the user program from the online CPU.

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11.9 Comparing offline and online CPUs

11.9

Comparing offline and online CPUs
You can compare the code blocks in an online CPU with the code blocks in your project. If
the code blocks of your project do not match the code blocks of the online CPU, the
"Compare" editor allows you to synchronize your project with the online CPU by downloading
the code blocks of your project to the CPU, or by deleting blocks from the project that do not
exist in the online CPU.
Select the CPU in your project.
Use the "Compare Offline/online" command to open the
"Compare" editor. (Access the command either from the "Tools"
menu or by right-clicking the CPU in your project.)

Click in the "Action" column for an object to
select whether to delete the object, take no
action, or download the object to the device.
Click the "Synchronize" button to load the code
blocks.

Right-click an object in the "Compare to" column and
select "Start detailed comparison" button to show the
code blocks side-by-side.
The detailed comparison highlights the differences
between the code blocks of online CPU and the code
blocks of the CPU in your project.

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11.10 Displaying the diagnostic events

11.10

Displaying the diagnostic events
The CPU provides a diagnostic buffer that contains an entry for each diagnostic event, such
as transition of the CPU operating mode or errors detected by the CPU or modules. To
access the diagnostic buffer, you must be online.
Each entry includes a date and time the event occurred, an event category, and an event
description. The entries are displayed in chronological order, with the most recent event at
the top.
While the CPU maintains power, up to
50 most recent events are available in
this log. When the log is full, a new
event replaces the oldest event in the
log.
When power is lost, the ten most
recent events are saved.

11.11

Setting the IP address and time of day
You can set the IP address and time of day in the online CPU. After accessing "Online &
diagnostics" from the Project tree for an online CPU, you can display or change the IP
address. You can also display or set the time and date parameters of the online CPU.

Note
This feature is available only for a CPU that either has only a MAC address (has not yet
been assigned an IP address) or has been reset to factory settings.

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11.12 Resetting to factory settings

11.12

Resetting to factory settings
You can reset an S7-1200 to its original factory settings under the following conditions:
● No memory card is inserted in the CPU.
● The CPU has an online connection.
● The CPU is in STOP mode.
Note
If the CPU is in RUN mode and you start the reset operation, you can place it in STOP
mode after acknowledging a confirmation prompt.

Procedure
To reset a CPU to its factory settings, follow these steps:
1. Open the Online and Diagnostics view of the CPU.
2. Select "Reset to factory settings" from the "Functions" folder.
3. Select the "Keep IP address" check box if you want to retain the IP address or the "Reset
IP address" check box if you want to delete the IP address.
4. Click the "Reset" button.
5. Acknowledge the confirmation prompt with "OK".

Result
The module is switched to STOP mode if necessary, and it is reset to the factory settings:
● The work memory and internal load memory and all operand areas are cleared.
● All parameters are reset to their defaults.
● The diagnostics buffer is cleared.
● The time of day is reset.
● The IP address is retained or deleted based on the setting you made. (The MAC address
is fixed and is never changed.)

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11.13 Updating firmware

11.13

Updating firmware
You can update the firmware of the connected CPU from the STEP 7 online and diagnostics
tools.
To perform a firmware update, follow these steps:
1. Open the Online and Diagnostics view of the connected CPU.
2. Select "Firmware update" from the "Functions" folder.
3. Click the Browse button and navigate to the location that contains the firmware update
file. This could be a location on your hard drive to which you have downloaded an
S7-1200 (http://support.automation.siemens.com/WW/view/en/34612486/133100)
firmware update file from the service and support Web site
(http://www.siemens.com/automation/).
4. Select a file that is compatible with your module. For a selected file, the table displays the
compatible modules.
5. Click the "Run update" button. Follow the dialogs, if necessary, to change the operating
mode of your CPU.
STEP 7 displays progress dialogs as it loads the firmware update. When it finishes, it
prompts you to start the module with the new firmware.
Note
If you do not choose to start the module with the new firmware, the previous firmware
remains active until you reset the module, for example by cycling power. The new firmware
becomes active only after you reset the module.
You can also perform a firmware update by one of the following additional methods:
● Using a memory card
● Using the Web server "Module Information" standard Web page (Page 194)

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11.14 Downloading an IP address to an online CPU

11.14

Downloading an IP address to an online CPU
To assign an IP address, you must perform the following tasks:
• Configure the IP
address for the CPU
(Page 80).
• Save and download the
configuration to the
CPU.

The IP address and subnet mask for the CPU must be compatible with the IP address and
subnet mask of the programming device. Consult your network specialist for the IP address
and subnet mask for your CPU.
If the CPU has not been previously configured, you can also
use "Online access" to set the IP address.
An IP address that you have downloaded with the device
configuration will not be lost on a power cycle of the PLC.

After you have downloaded the device configuration with the IP address, you can see the IP
address under the "Online access" folder.

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11.15 Using the "unspecified CPU" to upload the hardware configuration

11.15

Using the "unspecified CPU" to upload the hardware configuration
If you have a physical CPU that you can connect to the programming device, it is easy to
upload the configuration of the hardware.
You must first connect the CPU to your programming device, and you must create a new
project.
In the device configuration (Project view or Portal view),
add a new device, but select the "unspecified CPU"
instead of selecting a specific CPU. STEP 7 creates an
unspecified CPU.

After creating the unspecified CPU, you can upload the
hardware configuration for the online CPU.
• From the program editor, you select the "Hardware
detection" command from the "Online" menu.
• From the device configuration editor, you select the option
for detecting the configuration of the connected device

After you select the CPU from the online dialog, STEP 7 uploads the hardware configuration
from the CPU, including any modules (SM, SB, or CM). The IP address is not uploaded. You
must go to "Device configuration" to manually configure the IP address.

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11.16 Downloading in RUN mode

11.16

Downloading in RUN mode
The CPU supports "Download in RUN mode". This capability is intended to allow you to
make small changes to a user program with minimal disturbance to the process being
controlled by the program. However, implementing this capability also allows massive
program changes that could be disruptive or even dangerous.
WARNING
Risks with downloading in RUN mode
When you download changes to the CPU in RUN mode, the changes immediately affect
process operation. Changing the program in RUN mode can result in unexpected system
operation, which could cause death or serious injury to personnel, and/or damage to
equipment.
Only authorized personnel who understand the effects of RUN mode changes on system
operation should perform a download in RUN mode.
The "Download in RUN mode" feature allows you to make changes to a program and
download them to your CPU without switching to STOP mode:
● You can make minor changes to your current process without having to shut down (for
example, change a parameter value).
● You can debug a program more quickly with this feature (for example, invert the logic for
a normally open or normally closed switch).
You can make the following program block and tag changes and download them in RUN
mode:
● Create, overwrite, and delete Functions (FC), Function Blocks (FB), and Tag tables.
● Create, delete, and overwrite Data Blocks (DB) and instance data blocks for Function
Blocks (FB). You can add to DB structures and download them in RUN mode. The CPU
can maintain the values of existing block tags and initialize the new data block tags to
their initial values, or the CPU can set all data block tags to initial values, depending on
your configuration settings. You cannot download a web server DB (control or fragment)
in RUN mode.
● Overwrite Organization Blocks (OB); however, you cannot create or delete OBs.
You can download a maximum number of twenty blocks in RUN mode at one time. If you
must download more than twenty blocks, you must place the CPU in STOP mode.
If you download changes to a real process (as opposed to a simulated process, which you
might do in the course of debugging a program), it is vital to think through the possible safety
consequences to machines and machine operators before you download.
Note
If the CPU is in RUN mode and program changes have been made, STEP 7 always tries to
download in RUN first. If you do not want this to happen, you must put the CPU into STOP.
If the changes made are not supported in "Download in RUN", STEP 7 prompts the user that
the CPU must go to STOP.

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11.16 Downloading in RUN mode

11.16.1

Changing your program in RUN mode
To change the program in RUN mode, your must first ensure that the CPU and program
meet the prerequisites, and then follow these steps:
1. To download your program in RUN mode, select one of the following methods:
– Select the "Download to device" command from the "Online" menu.
– Click the "Download to device" button in the toolbar.
– In the "Project tree", right-click "Program blocks" and select the "Download to device >
Software" command.

If the program compiles successfully, STEP 7 starts to download the program to the CPU.
2. When STEP 7 prompts you to load your program or cancel the operation, click "Load" to
download the program to the CPU.

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11.17 Tracing and recording CPU data on trigger conditions

11.17

Tracing and recording CPU data on trigger conditions
STEP 7 provides trace and logic analyzer functions with which you can configure variables
for the PLC to trace and record. You can then upload the recorded trace data to your
programming device and use STEP 7 tools to analyze, manage, and graph your data. You
use the Traces folder in the STEP 7 project tree to create and manage traces.
The following figure shows the various steps of the trace feature:

①
②
③
④
⑤

Configure the trace in the trace editor of STEP 7. You can configure the data values to record,
the recording duration, the recording frequency, and the trigger condition.
Transfer the trace configuration from STEP 7 to the PLC.
The PLC executes the program, and when the trigger condition occurs, begins recording the
trace data.
Transfer the recorded values from the PLC to STEP 7.
Use the tools in STEP 7 to analyze the data, display it graphically, and save it.

Note that the trace feature is only available as of V4.0 of the S7-1200 CPU.
See the STEP 7 information system for details about how to program a trace, how to
download the configuration, upload the trace data, and display the data in the logic analyzer.

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IO-Link is easy
12.1

Overview of IO-Link technology
IO-Link is an innovative communication technology for sensors and actuators defined by the
PROFIBUS user organization (PNO). IO-Link is an international standard according to IEC
61131-9. It is based on a point-to-point connection between the sensors and actuators
(slaves) and the controller (master). It does not therefore represent a bus system, but is an
upgrade of the conventional point-to-point connection.
In addition to cyclic operating data, extensive parameter and diagnostic data is transmitted
by the connected sensors/actuators. The same 3-wire connecting cable that is used for
standard sensor technology is used for data transmission.

12.2

Components of an IO-Link system
An IO-Link system consists of IO-Link devices (usually sensors, actuators, or combinations
thereof), a standard 3-wire sensor/actuator cable, and an IO-Link master. The master can be
a device with any design and degree of protection.
An IO-Link master can have one or more ports. The SM 1278 4xIO-Link Master has four
ports. One IO-Link device or one standard sensor/actuator can be connected to each port.
IO-Link is a point-to-point communication system.

12.3

After power-up
At power-up, the IO-Link device is always in SIO mode (standard I/O mode). The ports of the
master can have different configurations. See the IO-Link chapter in the S7-1200 System
Manual for details.
If a port is set to SIO mode, the master acts on this port like a normal digital input. If the port
is set to IO-Link mode (communication mode), the master tries to find the connected IO-Link
device. This process is called wake-up.
During wake-up, the master sends a defined signal and waits for the slave device to
respond. Initially, the master attempts to do this with the highest possible baud rate. If this is
unsuccessful, the master tries the next lower baud rate. The master tries to address the
device three times with each baud rate. The device always supports only one defined baud
rate. If the master receives a response (that is, if the device has been woken up), both will
start communication. At first, they exchange the communication parameters, and then they
start the cyclical exchange of process data.
If the slave device is removed during operation, the master detects the communication abort,
reports it with fieldbus specificity to the controller, and attempts to wake up the device again
cyclically. After another successful wake-up, the communication parameters are read out
again, validated if applicable, and then the cyclic communication channel starts again.

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12.4 IO-Link protocol

12.4

IO-Link protocol
The IO-Link system can exchange three types of data:
● Cyclic process data (process data inputs, outputs) → Cyclic data
● Device parameters (on-request data objects) → Acyclic data
● Events → Acyclic data
The IO-Link device only sends data after being requested by the IO-Link master to do so.
Process data is sent after the IDLE frame of the master, and the master explicitly requests
device parameter data and events.

12.5

Configuration in the fieldbus
The IO-Link master appears on the fieldbus as a normal fieldbus node and is integrated via
the appropriate device description in the relevant network configurator. These files describe
the communication properties and other properties of the IO-Link master, such as the
number of ports. They do not indicate which IO-Link devices are connected.
However, the IO-Link Device Description (IODD) has been defined for full transparent
representation of the system architecture up to the IO-Link device. With the help of the IODD
and the IO-Link configuration tool S7-PCT, you can configure which IO-Link device is
connected to which port of your IO-Link master.
See the S7-PCT help system and the S7-1200 System Manual for detailed configuration
information.

12.6

IO-Link and your STEP 7 program
The IO-Link master programs acyclic communication with an IO-Link device using the
IOL_CALL function block (FB) in your STEP 7 S7-1200 controller program. The IOL_CALL
FB indicates the IO-Link master your program uses, and which ports the master uses for
data exchange.
Visit the Siemens Industry Online Support website (http://support.automation.siemens.com)
for details on working with the IOL_CALL FB. Enter "IO-Link" in the website's search box to
access information about IO-Link products and their use.

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12.7 The SM 1278 4xIO-Link Master

12.7

The SM 1278 4xIO-Link Master
The SM 1278 4xIO-Link Master is a 4-port module that functions as both a signal module
and a communication module. Each port can operate in the IO-Link mode, single 24 VDC
digital input or 24 VDC digital output. You can connect up to four IO-Link devices (3-wire
connection) or four standard actuators or standard encoders.

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12.7 The SM 1278 4xIO-Link Master

SM 1278 4xIO-Link Master block diagram

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12.7 The SM 1278 4xIO-Link Master

Connection examples
The following illustration shows the configuration for IO-Link operating mode (3-wire and
5-wire), where n = port number:

The following illustration shows the configuration for DI operating mode (2-wire and 3-wire),
where n = port number:

The following illustration shows the configuration for DQ operating mode (2-wire and 3-wire),
where n = port number:

Detailed information on using and configuring the SM 1278 4xIO-Link Master
For detailed information on the SM 1278 4xIO-Link Master, including diagrams, connection,
parameterization, diagnostic alarms and more, refer to the S7-1200 System Manual.

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12.7 The SM 1278 4xIO-Link Master

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A.1

General technical specifications

Standards compliance
The S7-1200 automation system design conforms with the following standards and test
specifications. The test criteria for the S7-1200 automation system are based on these
standards and test specifications.
Note that not all S7-1200 models may be certified to these standards, and certification status
may change without notification. It is your responsibility to determine applicable certifications
by referring to the ratings marked on the product. Consult your local Siemens representative
if you need additional information related to the latest listing of exact approvals by part
number.

CE approval
The S7-1200 Automation System satisfies requirements and safety related objectives
according to the EC directives listed below, and conforms to the harmonized European
standards (EN) for the programmable controllers listed in the Official Journals of the
European Community.
● EC Directive 2006/95/EC (Low Voltage Directive) "Electrical Equipment Designed for Use
within Certain Voltage Limits"
– EN 61131-2:2007 Programmable controllers - Equipment requirements and tests
● EC Directive 2004/108/EC (EMC Directive) "Electromagnetic Compatibility"
– Emission standard
EN 61000-6-4:2007: Industrial Environment
– Immunity standard
EN 61000-6-2:2005: Industrial Environment
● EC Directive 94/9/EC (ATEX) "Equipment and Protective Systems Intended for Use in
Potentially Explosive Atmosphere"
– EN 60079-15:2005: Type of Protection 'n'
The CE Declaration of Conformity is held on file available to competent authorities at:
Siemens AG
IA AS RD ST PLC Amberg
Werner-von-Siemens-Str. 50
D92224 Amberg
Germany

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cULus approval
Underwriters Laboratories Inc. complying with:
● Underwriters Laboratories, Inc.: UL 508 Listed (Industrial Control Equipment)
● Canadian Standards Association: CSA C22.2 Number 142 (Process Control Equipment)
Note
The SIMATIC S7-1200 series meets the CSA standard.
The cULus logo indicates that the S7-1200 has been examined and certified by
Underwriters Laboratories (UL) to standards UL 508 and CSA 22.2 No. 142.

FM approval
Factory Mutual Research (FM)
Approval Standard Class Number 3600 and 3611
Approved for use in:
Class I, Division 2, Gas Group A, B, C, D, Temperature Class T3C Ta = 60 °C
Class I, Zone 2, IIC, Temperature Class T3 Ta = 60 °C
Canadian Class I, Zone 2 Installation per CEC 18-150
IMPORTANT EXCEPTION: See Technical Specifications for the number of inputs or outputs
allowed on simultaneously. Some models are de-rated for Ta = 60 °C.
WARNING
Substitution of components can impair the suitability for Class I, Division 2 and Zone 2.
Repair of units should only be performed by an authorized Siemens Service Center.

ATEX approval
ATEX approval applies to DC models only. ATEX approval does not apply to AC and Relay
models.
EN 60079-0:2009: Explosive Atmospheres - General Requirements
EN 60079-15:2010: Electrical Apparatus for Potentially Explosive Atmospheres;
Type of protection 'nA'
II 3 G Ex nA IIC T4 or T3 Gc
Install modules in a suitable enclosure providing a minimum degree of protection of IP54
according to EN 60529, or in a location providing an equivalent degree of protection.
Attached cables and conductors should be rated for the actual temperature measured under
rated conditions.
The installation should ensure that transients are limited to less than 119 V. See Surge
immunity in this section.
IMPORTANT EXCEPTION: See Technical Specifications for the number of inputs or outputs
allowed on simultaneously. Some models are de-rated for Ta = 60 °C.

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C-Tick approval
The S7-1200 automation system satisfies requirements of standards to AS/NZS 2064
(Class A).

Korea Certification
The S7-1200 automation system satisfies the requirements of the Korean Certification (KC
Mark). It has been defined as Class A Equipment and is intended for industrial applications
and has not been considered for home use.

Maritime approval
The S7-1200 products are periodically submitted for special agency approvals related to
specific markets and applications. Consult your local Siemens representative if you need
additional information related to the latest listing of exact approvals by part number.
Classification societies:
● ABS (American Bureau of Shipping)
● BV (Bureau Veritas)
● DNV (Det Norske Veritas)
● GL (Germanischer Lloyd)
● LRS (Lloyds Register of Shipping)
● Class NK (Nippon Kaiji Kyokai)
● Korean Register of Shipping

Industrial environments
The S7-1200 automation system is designed for use in industrial environments.
Table A- 1

Industrial environments

Application field

Noise emission requirements

Noise immunity requirements

Industrial

EN 61000-6-4:2007

EN 61000-6-2:2005

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Electromagnetic compatibility
Electromagnetic Compatibility (EMC) is the ability of an electrical device to operate as
intended in an electromagnetic environment and to operate without emitting levels of
electromagnetic interference (EMI) that may disturb other electrical devices in the vicinity.
Table A- 2

Immunity per EN 61000-6-2

Electromagnetic compatibility - Immunity per EN 61000-6-2
EN 61000-4-2
Electrostatic discharge

8 kV air discharge to all surfaces
6 kV contact discharge to exposed conductive surfaces

EN 61000-4-3
Radiated, radio-frequency,
electromagnetic field immunity test

80 to 1000 MHz, 10 V/m, 80% AM at 1 kHz
1.4 to 2.0 GHz, 3 V/m, 80% AM at 1 kHz
2.0 to 2.7 GHz, 1 V/m, 80% AM at 1 kHz

EN 61000-4-4
Fast transient bursts

2 kV, 5 kHz with coupling network to AC and DC system power
2 kV, 5 kHz with coupling clamp to I/O

EN 6100-4-5
Surge immunity

AC systems - 2 kV common mode, 1 kV differential mode
DC systems - 2 kV common mode, 1 kV differential mode
For DC systems, refer to Surge immunity below

EN 61000-4-6
Conducted disturbances

150 kHz to 80 MHz, 10 V RMS, 80% AM at 1kHz

EN 61000-4-11
Voltage dips

AC systems
0% for 1 cycle, 40% for 12 cycles and 70% for 30 cycles at 60 Hz

Surge immunity
Wiring systems subject to surges from lightning strike coupling must be equipped with
external protection. One specification for evaluation of protection from lightning type surges
is found in EN 61000-4-5, with operational limits established by EN 61000-6-2. S7-1200 DC
CPUs and signal modules require external protection to maintain safe operation when
subject to surge voltages defined by this standard.
Listed below are some devices that support the needed surge immunity protection. These
devices only provide the protection if they are properly installed according to the
manufacturer's recommendations. Devices manufactured by other vendors with the same or
better specifications can also be used:
● Supply Voltage, 24 VDC: DEHN, Inc., Type BVT AD 24, Part Number 918 402
● Digital Inputs, 24 VDC: DEHN, Inc., Type DCO RK E 24, Part Number 919 988
● Digital Outputs, 24 VDC: DEHN, Inc., Type DCO RK E 24, Part Number 919 988
● Analog Inputs: DEHN, Inc., Type BXT ML4 BD12, Part Number 920 342
● Analog Outputs: DEHN, Inc., Type DCO RK E 12, Part Number 919 987
● Ethernet: DEHN, Inc., Type DPA M CAT6 RJ45S 48, Part Number 929 100
● RS-232: DEHN, Inc., Type DCO RK E 12, Part Number 919 987
● RS-485: DEHN, Inc., Type BXT ML2 BE HFS 5, Part Number 920 270
● Relay Outputs: None required

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Table A- 3

Conducted and radiated emissions per EN 61000-6-4

Electromagnetic compatibility - Conducted and radiated emissions per EN 61000-6-4
Conducted Emissions

0.15 MHz to 0.5 MHz

<79dB (μV) quasi-peak; <66 dB (μV) average

EN 55011, Class A, Group 1

0.5 MHz to 5 MHz

<73dB (μV) quasi-peak; <60 dB (μV) average

5 MHz to 30 MHz

<73dB (μV) quasi-peak; <60 dB (μV) average

Radiated Emissions

30 MHz to 230 MHz

<40dB (μV/m) quasi-peak; measured at 10m

EN 55011, Class A, Group 1

230 MHz to 1 GHz

<47dB (μV/m) quasi-peak; measured at 10m

Environmental conditions
Table A- 4

Transport and storage

Environmental conditions - Transport and storage
EN 60068-2-2, Test Bb, Dry heat and
EN 60068-2-1, Test Ab, Cold

-40 °C to +70 °C

EN 60068-2-30, Test Db, Damp heat

25 °C to 55 °C, 95% humidity

EN 60068-2-14, Test Na, temperature shock

-40 °C to +70 °C, dwell time 3 hours, 5 cycles

EN 60068-2-32, Free fall

0.3 m, 5 times, product packaging

Atmospheric pressure

1080 to 660h Pa (corresponding to an altitude of -1000 to 3500m)

Table A- 5

Operating conditions

Environmental conditions - Operating
Ambient temperature range
(Inlet Air 25 mm below unit)

-20 °C to 60 °C horizontal mounting
-20 °C to 50 °C vertical mounting
95% non-condensing humidity
Unless otherwise specified

Atmospheric pressure

1080 to 795 hPa (corresponding to an altitude of -1000 to 2000m)

Concentration of contaminants

S02: < 0.5 ppm; H2S: < 0.1 ppm; RH < 60% non-condensing

EN 60068-2-14, Test Nb, temperature change

5 °C to 55 °C, 3 °C/minute

EN 60068-2-27 Mechanical shock

15 G, 11 ms pulse, 6 shocks in each of 3 axis

EN 60068-2-6 Sinusoidal vibration

DIN rail mount: 3.5 mm from 5-9 Hz, 1G from 9 - 150 Hz
Panel Mount: 7.0 mm from 5-9 Hz, 2G from 9 to 150 Hz
10 sweeps each axis, 1 octave per minute

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Table A- 6

High potential isolation test

High potential isolation test
24 VDC / 5 VDC nominal circuits

520 VDC (type test of optical isolation boundaries)

115 VAC / 230 VAC circuits to ground

1500 VAC

115 VAC / 230 VAC circuits to 115 VAC / 230 VAC
circuits

1500 VAC

115 VAC / 230 VAC circuits to 24 VDC / 5 VDC
circuits

1500 VAC (type test only)

1500 VAC (3000 VAC/4242 VDC type test)

Ethernet port to 24 VDC / 5 VDC circuits and
ground1
1

Ethernet port isolation is designed to limit hazard during short term network faults to hazardous voltages. It does not
conform to safety requirements for routine AC line voltage isolation.

Protection class
● Protection Class II according to EN 61131-2 (Protective conductor not required)

Degree of protection
● IP20 Mechanical Protection, EN 60529
● Protects against finger contact with high voltage as tested by standard probe. External
protection required for dust, dirt, water and foreign objects of < 12.5mm in diameter.

Rated voltages
Table A- 7

Rated voltages

Rated voltage

Tolerance

24 VDC

20.4 VDC to 28.8 VDC

120/230 VAC

85 VAC to 264 VAC, 47 to 63 Hz

Note
When a mechanical contact turns on output power to the S7-1200 CPU, or any digital signal
module, it sends a "1" signal to the digital outputs for approximately 50 microseconds. This
could cause unexpected machine or process operation which could result in death or serious
injury to personnel and/or damage to equipment. You must plan for this, especially if you are
using devices which respond to short duration pulses.

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Reverse voltage protection
Reverse voltage protection circuitry is provided on each terminal pair of +24 VDC power or
user input power for CPUs, signal modules (SMs), and signal boards (SBs). It is still possible
to damage the system by wiring different terminal pairs in opposite polarities.
Some of the 24 VDC power input ports in the S7-1200 system are interconnected, with a
common logic circuit connecting multiple M terminals. For example, the following circuits are
interconnected when designated as "not isolated" in the data sheets: the 24 VDC power
supply of the CPU, the sensor power of the CPU, the power input for the relay coil of an SM,
and the power supply for a non-isolated analog input. All non-isolated M terminals must
connect to the same external reference potential.
WARNING
Connecting non-isolated M terminals to different reference potentials will cause unintended
current flows that may cause damage or unpredictable operation in the PLC and any
connected equipment.
Failure to comply with these guidelines could cause damage or unpredictable operation
which could result in death or severe personal injury and/or property damage.
Always ensure that all non-isolated M terminals in an S7-1200 system are connected to the
same reference potential.

DC Outputs
Short -ircuit protection circuitry is not provided for DC outputs on CPUs, signal modules
(SMs) and signal boards (SBs).

Relay electrical service life
The typical performance data estimated from sample tests is shown below. Actual
performance may vary depending upon your specific application. An external protection
circuit that is adapted to the load will enhance the service life of the contacts. N.C. contacts
have a typical service life of about one-third that of the N.O. contact under inductive and
lamp load conditions.
An external protective circuit will increase the service life of the contacts.

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Table A- 8

Typical performance data

Data for selecting an actuator
Continuous thermal current

2 A max.

Switching capacity and life of the contacts
For ohmic load

Voltage

Current

Number of operating cycles (typical)

24 VDC

2.0 A

0.1 million

24 VDC

1.0 A

0.2 million

24 VDC

0.5 A

1.0 million

48 VAC

1.5 A

1.5 million

60 VAC

1.5 A

1.5 million

120 VAC

2.0 A

1.0 million

120 VAC

1.0 A

1.5 million

120 VAC

0.5 A

2.0 million

230 VAC

2.0 A

1.0 million

230 VAC

1.0 A

1.5 million

230 VAC

0.5 A

12.0 million

For inductive load (according to

Voltage

Current

Number of operating cycles (typical)

IEC 947-5-1 DC13/AC15)

24 VDC

2.0 A

0.05 million

24 VDC

1.0 A

0.1 million

24 VDC

0.5 A

0.5 million

24 VAC

1.5 A

1.0 million

48 VAC

1.5 A

1.0 million

60 VAC

1.5 A

1.0 million

120 VAC

2.0 A

0.7 million

120 VAC

1.0 A

1.0 million

120 VAC

0.5 A

1.5 million

230 VAC

2.0 A

0.7 million

230 VAC

1.0 A

1.0 million

230 VAC

0.5 A

1.5 million

Activating a digital input

Possible

Switching frequency
Mechanical

Max. 10 Hz

At ohmic load

Max. 1 Hz

At inductive load (according to
IEC 947-5-1 DC13/AC15)

Max. 0.5 Hz

At lamp load

Max. 1Hz

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A.2 CPU modules

A.2

CPU modules
For a more complete list of modules available for S7-1200, refer to the S7-1200 System
Manual or to the customer support web site (http://www.siemens.com/automation/).

Table A- 9

General specifications

CPU 1211C

Order
number

Power
dissipation

CPU 1214C

CPU 1215C

CPU 1217C

•

AC/DC/Relay

•

6ES7 2111BE400XB0

•

6ES7 2121BE400XB0

•

6ES7 2141BG400XB0

•

6ES7 2151BG400XB0

•

DC/DC/Relay

•

6ES7 2111HE400XB0

•

6ES7 2121HE400XB0

•

6ES7 2141HG400XB0

•

6ES7 2151HG400XB0

•

DC/DC/DC

•

6ES7 2111AE400XB0

•

6ES7 2121AE400XB0

•

6ES7 2141AG400XB0

•

6ES7 2151AG400XB0

•

6ES7 2171AG400XB0

Dimensions W x H x D (mm)
Weight

CPU 1212C

90 x 100 x 75

110 x 100 x 75

130 x 100 x 75

150 x 100 x 75
-

•

AC/DC/Relay

•

420 grams

•

425 grams

•

475 grams

•

585 grams

•

DC/DC/Relay

•

380 grams

•

385 grams

•

435 grams

•

550 grams

•

DC/DC/DC

•

370 grams

•

370 grams

•

415 grams

•

520 grams

530 grams

•

AC/DC/Relay

•

10 W

•

11 W

•

14 W

•

14 W

•

DC/DC/Relay

•

12 W

•

12 W

•

DC/DC/DC

•

12 W

•

12 W

Current available (5 VDC) for
SM and CM bus

750 mA max.

1000 mA max.

1600 mA max.

Current available (24 VDC)
sensor power

300 mA max.

400 mA max.

Digital input current
consumption (24 VDC)

4 mA/input
used

4 mA/inputs
used

4 mA/input used

Table A- 10

CPU features

CPU 1211C

CPU 1212C

CPU 1214C

CPU 1215C

CPU 1217C

User memory
•

Work memory

•

30 Kbytes

•

50 Kbytes

•

75 Kbytes

•

100 Kbytes

•

125 Kbytes

•

Load memory

•

1 Mbyte

•

1 Mbyte

•

4 Mbytes

•

4 Mbytes

•

4 Mbytes

•

Retentive memory

•

10 Kbytes

•

10 Kbytes

•

10 Kbytes

•

10 Kbytes

•

10 Kbytes

On-board digital I/O

6 inputs

8 inputs

14 inputs

See specifications
(Page 302).

4 outputs

6 outputs

10 outputs

On-board analog I/O

2 inputs

2 outputs

See specifications
(Page 311).

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A.2 CPU modules

CPU features

CPU 1211C

CPU 1212C

CPU 1214C

CPU 1215C

CPU 1217C

Process image size
•

Inputs

•

1024 bytes

•

1024 bytes

•

1024 bytes

•

1024 bytes

•

1024 bytes

•

Outputs

•

1024 bytes

•

1024 bytes

•

1024 bytes

•

1024 bytes

•

1024 bytes

Bit memory (M)

4096 bytes

8192 bytes

Temporary (local) memory

•

16 Kbytes for startup and program cycle (including associated FBs and FCs)

•

6 Kbytes for each of the other interrupt priority levels (including FBs and FCs)

SM expansion

None

2 SMs max.

8 SMs max.

SB, CB, or BB expansion

1 max.

CM expansion

3 max.

3 max

Highspeed
counters

Total

Up to 6 configured to use any built-in or SB inputs

1 MHz

Ib.2 to Ib.5
(Differential)

100/180 kHz

Ia.0 to Ia.5

30/120

Ia.6 to Ia.7

Ia.6 to Ib.5

Ia.6 to Ib.1

Pulse
outputs2

kHz

Total

Up to 4 configured to use any built-in or SB outputs

1 MHz

Qa.0 to Qa.3
(Differential)

100 kHz

Qa.0 to Qa.3

Qa.0to Qa.3

Qa.0 to Qa.3

Qa.4 to Qb.1

30 kHz

Qa.4 to Qa.5

Qa.4 to Qb.1

Pulse catch inputs

Time delay interrupts

4 total with 1 ms
resolution

Cyclic interrupts

4 total with 1 ms
resolution

Edge interrupts

6 rising and 6
falling

8 rising and 8
falling

12 rising and 12
falling

With optional SB

10 rising and 10
falling

12 rising and 12
falling

16 rising and 16
falling

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A.2 CPU modules

CPU features

CPU 1211C

CPU 1212C

CPU 1214C

CPU 1215C

CPU 1217C

Real time clock
+/- 60
seconds/
month

+/- 60
seconds/
month

•

Accuracy

•

Retention time
(maintenance-free
Super Capacitor)

+/- 60
seconds/
month

•

•
20 days
typ./12 days
min. at 40 °C

20 days
typ./12 days
min. at 40 °C

•

Execution speed
•

Boolean

•

0.08 μs/
instruction

•

0.08 μs/
instruction

•

0.08 μs /
instruction

•

0.08 μs/
instruction

•

0.08 μs/
instruction

•

Move Word

•

1.7μs/
instruction

•

1.7 μs/
instruction

•

1.7μs/
instruction

•

1.7μs/
instruction

•

1.7 μs/
instruction

•

Real Math

•

2.3 μs/
instruction

•

2.3 μs/
instruction

•

2.3 μs/
instruction

•

2.3 μs/
instruction

•

2.3 μs/
instruction

The slower speed is applicable when the HSC is configured for quadrature mode of operation.

For CPU models with relay outputs, you must install a digital signal board (SB) to use the pulse outputs.

Table A- 11

Communication

Technical data

CPU 1211C, CPU 1212C, CPU 1214C

CPU 1215C, CPU 1217C

Communication

1 Ethernet port

2 Ethernet ports

•

Data rates

•

Isolation (external signal •
to PLC logic)
•
Cable type

•

Devices

10/100 Mb/s

•

10/100 Mb/s

Transformer isolated, 1500 VDC

•

Transformer isolated, 1500 VDC

CAT5e shielded

•

CAT5e shielded

•

4 HMI

•

4 HMI

•

1 PG

•

1 PG

•

Ethernet connections1

8 (active or passive)

CPU-to-CPU
S7 connections (GET/PUT)

•

8 (client)

•

8 (client)

•

3 (server)

•

3 (server)

Open User Communication connections (active or passive): TSEND_C, TRCV_C, TCON, TDISCON, TSEND, and
TRCV.

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Table A- 12

Wiring diagram for CPU 1214C AC/DC/Relay

CPU 1214C AC/DC/Relay

①

24 VDC Sensor Power Out. For
additional noise immunity, connect "M"
to chassis ground even if not using
sensor supply.

②

For sinking inputs, connect "-" to "M"
(shown). For sourcing inputs, connect
"+" to "M".

Note 1: X11 connectors must be gold. See
the S7-1200 System Manual, Appendix C,
Spare Parts for order number.
Note 2: Either the L1 or N (L2) terminal can
be connected to a voltage source up to
240 VAC. The N terminal can be
considered L2 and is not required to be
grounded. No polarization is required for L1
and N (L2) terminals.

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A.3 Digital I/O modules
Table A- 13

Wiring diagram for CPU 1214C DC/DC/DC

CPU 1214C DC/DC/DC

①

24 VDC Sensor Power Out. For
additional noise immunity, connect "M"
to chassis ground even if not using
sensor supply.

②

For sinking inputs, connect "-" to "M"
(shown). For sourcing inputs, connect
"+" to "M".

Note 1: X11 connectors must be gold. See
the S7-1200 System Manual, Appendix C,
Spare Parts for order number.

A.3

Digital I/O modules
For a more complete list of modules available for S7-1200, refer to the S7-1200 System
Manual or to the customer support web site (http://www.siemens.com/automation/).

A.3.1
Table A- 14

SB 1221, SB 1222, and SB 1223 digital input/output (DI, DQ, and DI/DQ)
SB 1221 digital input (DI) and SB 1222 digital output (DQ) modules

General

SB 1221 4 DI (200 kHz)

Order number

SB 1222 4 DQ (200 kHz)

•

24 VDC: 6ES7 221-3BD30-0XB0

•

24 VDC: 6ES7 222-1BD30-0XB0

•

5 VDC: 6ES7 221-3AD30-0XB0

•

5 VDC: 6ES7 222-1AD30-0XB0

Dimensions W x H x D (mm)

38 x 62 x 21

Weight

35 grams

Power dissipation

•

24 VDC: 1.5 W

•

5 VDC: 1.0 W

Current
consumption

SM Bus

40 mA

24 VDC

•

24 VDC: 7 mA / input + 20 mA

•

5 VDC: 15 mA / input + 15 mA

Inputs/outputs

4 inputs (source)

0.5 W
35 mA
15 mA
4 outputs (solid state - MOSFET)

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Table A- 15

SB 1223 combination digital input/output (DI / DQ) modules

General

SB 1223 DI / DQ (200 kHz)

Order number

•

24 VDC: 6ES7 223-3BD30-0XB0

•

5 VDC: 6ES7 223-3AD30-0XB0

SB 1223 2 DI / 2 DQ
24 VDC: 6ES7 223-0BD30-0XB0

Dimensions W x H x D (mm)

38 x 62 x 21

Weight

35 grams

40 grams

Power dissipation

•

24 VDC: 1.0 W

•

5 VDC: 0.5 W

Current
consumption

SM Bus

35 mA

24 VDC

•

24 VDC: 7 mA / input + 20 mA

•

5 VDC: 15 mA / input + 15 mA

Inputs/outputs

24 VDC: 1.0 W
50 mA
4 mA / input used

2 inputs (source)

2 inputs (IEC Type 1 sink)

2 outputs (solid state - MOSFET)

Note
The high-speed (200 kHz) SBs utilize "sourcing" inputs. The standard SB (20 kHz) utilizes
"sinking" inputs. Refer to the specifications for the digital inputs and outputs (Page 302).
The high-speed (200 kHz) outputs (SB 1222 and SB 1223) can be either sourcing or sinking.
For sourcing outputs, connect "Load" to "-" (shown). For sinking outputs, connect "Load" to
"+". Because both sinking and sourcing configurations are supported by the same circuitry,
the active state of a sourcing load is opposite that of a sinking load. A source output exhibits
positive logic (Q bit and LED are ON when the load has current flow), while a sink output
exhibits negative logic (Q bit and LED are OFF when the load has current flow). If the
module is plugged in with no user program, the default for this module is 0V, which means
that a sinking load will be turned ON.

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Table A- 16

Wiring diagrams for digital SBs

SB 1221 input module
SB 1221 DI 4 (200 kHz)

① Supports sourcing inputs only.

SB 1222 output module
SB 1222 DQ 4 (200 kHz)

① For sourcing outputs, connect

"Load" to "-" (shown). For sinking
outputs, connect "Load" to "+".
Because both sinking and sourcing
configurations ae supported by the
same circuitry, the active state of a
sourcing load is opposite that of a
sinking load. A source output exhibits
positive logic (Q bit and LED are ON
when the load has current flow), while a
sink output exhibits negative logic (Q
bit and LED are OFF when the load
has current flow). If the module is
plugged in with no user program, the
default for this module is 0 V, which
means that a sinking load will be turned
ON.

SB 1223 input/output module
SB 1223 DI 2 / DQ 2 (200 kHz)

① Supports sourcing inputs only.
② For sourcing outputs, connect

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Note
The high-speed (200 kHz) SBs (SB 1221 and SB 1223) support only sinking inputs. The
standard SB 1223 supports only sourcing inputs.
The high-speed (200 kHz) outputs (SB 1222 and SB 1223) can be either sourcing or sinking.
For sourcing outputs, connect "Load" to "-" (shown). For sinking outputs, connect "Load" to
"+". Because both sinking and sourcing configurations are supported by the same circuitry,
the active state of a sourcing load is opposite that of a sinking load. A source output exhibits
positive logic (Q bit and LED are ON when the load has current flow), while a sink output
exhibits negative logic (Q bit and LED are OFF when the load has current flow). If the
module is plugged in with no user program, the default for this module is 0 V, which means
that a sinking load will be turned ON.

A.3.2
Table A- 17

SM 1221 digital input (DI)
SM 1221 digital input (DI)

Technical data

SM 1221 DI 8 24 VDC

SM 1221 DI 16 24 VDC

Order number

6ES7 221-1BF32-0XB0

6ES7 221-1BH32-0XB0

Number of inputs (DI)

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

170 grams

210 grams

See specifications (Page 302).

Power dissipation
Current consumption

1.5 W

2.5 W

SM Bus

105 mA

130 mA

24 VDC

4 mA / input used

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A.3 Digital I/O modules
Table A- 18

Wiring diagram for SM 1221 digital input (DI) modules

SM 1221 DI 8 (24 VDC)

SM 1221 DI 16 (24 VDC)

① For sinking inputs, connect "-" to "M" (shown). For sourcing inputs connect "+" to "M".

A.3.3
Table A- 19

SM 1222 digital output (DQ)
SM 1222 digital output (DQ)

Technical data

SM 1222 DQ (Relay)

Order number

•

DQ 8: 6ES7 222-1HF32-0XB0

•

DQ 8: 6ES7 222-1BF32-0XB0

•

DQ 8: Changeover: 6ES7 2221XF32-0XB0

•

DQ 16: 6ES7 222-1BH32-0XB0

•

DQ 16: 6ES7 222-1HH32-0XB0

Number of outputs (DQ)

•

8 (DQ 8 and DQ 8 Changeover)

•

See specifications (Page 302).

8 (DQ 8)

•

16 (DQ 16)

•

16 (DQ 16)

Dimensions W x H x D (mm)

•

DQ 8 and DQ 16: 45 x 100 x 75

45 x 100 x 75

•

DQ 8 Changeover: 70 x 100 x 75

•

DQ 8: 190 grams

•

DQ 8: 180 grams

•

DQ 8 Changeover: 310 grams

•

DQ 16: 220 grams

•

DQ 16: 260 grams

Weight

SM 1222 DQ (24 VDC)

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A.3 Digital I/O modules

Technical data

SM 1222 DQ (Relay)

Power dissipation

•

DQ 8: 4.5 W

•

DQ 8: 1.5 W

•

DQ 8 Changeover: 5 W

•

DQ 16: 2.5 W

•

DQ 16: 8.5 W

•

DQ 8: 120 mA

•

DQ 8: 120 mA

•

DQ 8 Changeover: 140 mA

•

DQ 16: 140 mA

•

DQ 16: 135 mA

•

DQ 8 and DQ 16:11 mA / Relay coil
used

•

DQ 8: --

•

DQ 8 Changeover: 16.7 mA Relay
coil used

DQ 16: --

Current consumption SM Bus

24 VDC

Table A- 20

SM 1222 DQ (24 VDC)

Wiring diagram for SM 1222 digital output (DQ) modules

SM 1222 DQ 16, 24 VDC

SM 1222 DQ 16, Relay output

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A.3 Digital I/O modules

A.3.4
Table A- 21

SM 1223 VDC digital input/output (DI / DQ)
SM 1223 combination digital input / output (DI / DQ)

Technical data

SM 1223 DI (24 VDC) / DQ (Relay)

SM 1223 DI (24 VDC) / DQ (24 VDC)

Order number

DI 8 / DQ 8: 6ES7 223-1PH32-0XB0

DI 8 / DQ 8: 6ES7 223-1BH32-0XB0

DI 16 / DQ 16: 6ES7 223-1PL32-0XB0

DI 8 / DQ 8: 6ES7 223-1BL32-0XB0

Number of inputs / outputs (DI
/ DQ)

•

Inputs: 8 or 16 (24 VDC)

•

Inputs: 8 or 16 (24 VDC)

•

Outputs: 8 or 16 (relay)

•

Outputs: 8 or 16 (24 VDC)

Dimensions W x H x D
(mm)

•

DI 8 / DQ 8: 45 x 100 x 75

•

DI 8 / DQ 8: 45 x 100 x 75

•

DI 16 / DQ 16: 70 x 100 x 75

•

DI 16 / DQ 16: 70 x 100 x 75

Weight

•

DI 8 / DQ 8: 230 grams

•

DI 8 / DQ 8: 210 grams

•

DI 16 / DQ 16: 350 grams

•

DI 16 / DQ 16: 310 grams

See specifications (Page 302).

Power dissipation
Current
consumption

SM Bus
24 VDC

•

DI 8 / DQ 8: 5.5 W

•

DI 8 / DQ 8: 2.5 W

•

DI 16 / DQ 16: 10 W

•

DI 16 / DQ 16: 4.5 W

•

DI 8 / DQ 8: 145 mA

•

DI 8 / DQ 8: 145 mA

•

DI 16 / DQ 16: 180 mA

•

DI 16 / DQ 16: 185 mA

4 mA / input used
11 mA / Relay coil used

4 mA / input used

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Table A- 22

Wiring diagram for SM 1223 combination DI / DQ modules

SM 1223 DI 16 (24 VDC) / DQ 16 (24 VDC)

SM 1223 DI 16 (24 VDC) / DQ 16 (Relay)

① For sinking inputs, connect "-" to "M" (shown). For sourcing inputs, connect "+" to "M".

A.3.5
Table A- 23

SM 1223 120/230 VAC input / Relay output
SM 1223 combination VAC digital input / output (DI / DQ)

Technical data

SM 1223 DI (120/230 VAC) / DQ (Relay)

Order number

DI 8 / DQ 8: 6ES7 223-1QH32-0XB0

Number of inputs / outputs (DI / DQ)

Inputs: 8 (120/230 VAC)
See the specifications for 120/230 VAC inputs (Page 303).
Outputs: 8 (relay)
See the specifications for the digital outputs (Page 304).

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

190 grams

Power dissipation

7.5 W

Current
consumption

SM Bus

120 mA

24 VDC

11 mA / relay coil used

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A.3 Digital I/O modules

Note
The SM 1223 DI 8 x 120/230 VAC, DQ 8 x Relay signal module (6ES7 223-1QH32-0XB0) is
approved for use in Class 1, Division 2, Gas Group A, B, C, D, Temperature
Class T4 Ta = 40 °C.

Table A- 24

Wiring diagram for SM 1223 DI 8 (120/230 VAC) / DQ 8 (Relay)

SM 1223 DI 8 (120/230 VAC) / DQ 8 (Relay)

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A.4 Specifications for the digital inputs and outputs

A.4

Specifications for the digital inputs and outputs

A.4.1

24 VDC digital inputs (DI)

Table A- 25

Specifications for the digital inputs (DI)

Technical data
Type

Rated voltage

CPU, SM and SB
•

CPU and SM: IEC Type 1 sink
(Sink/Source)

•

SB 1223: IEC Type 1 sink
(Sink only)

24 VDC at 4 mA, nominal

High-speed SB (200 KHz)
SB 1221 200 KHz and SB 1223 200 KHz:
Source

24 VDC SB: 24 VDC at 7 mA, nominal
5 VDC SB: 5 VDC at 15 mA, nominal

Continuous permissible
voltage

30 VDC, max.

Surge voltage

35 VDC for 0.5 sec.

24 VDC SB: 28.8 VDC
5 VDC SB: 6 VDC
24 VDC SB: 35 VDC for 0.5 sec
5 VDC SB: 6 V

Logic 1 signal (min.)

15 VDC at 2.5 mA

24 VDC SB: L+ minus 10 VDC at 2.9 mA
5 VDC SB: L+ minus 2.0 VDC at 5.1 mA

Logic 0 signal (max.)

5 VDC at 1 mA

24 VDC SB: L+ minus 5 VDC at 1.4 mA
5 VDC SB: L+ minus 1.0 VDC at 2.2 mA

Isolation (field side to logic)

500 VAC for 1 minute

Isolation groups

•

CPU: 1

•

SB 1221 DI 4: 1

•

SM 1221 DI 8: 2

•

SB 1223 DI 2: 1

•

SM 1221 DI 16: 4

•

SB 1223 DI 2: 1

•

SM 1223: 2

Filter times
Number of inputs on
simultaneously

Cable length (meters)

0.2, 0.4, 0.8, 1.6, 3.2, 6.4, and 12.8 ms
(selectable in groups of 4)

500 VAC for 1 minute

0.2, 0.4, 0.8, 1.6, 3.2, 6.4, and 12.8 ms
(selectable in groups of 4)

•

SM 1221 and SM 1223 DI 8: 8

•

SB 1221 DI 4: 4

•

SM 1221 and SM 1223 DI 16: 16

•

SB 1223 DI 2: 2

•

SB 1223 DI 2: 2

•

500 m shielded, 300 m unshielded

•

CPU: 50 m shielded for HSC

50 m shielded twisted pair

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A.4 Specifications for the digital inputs and outputs

Note
When switching frequencies above 20 KHz, it is important that the digital inputs receive a
square wave. Consider the following options to improve the signal quality to the inputs:
• Minimize the cable length
• Change a driver from a sink only driver to a sinking and sourcing driver
• Change to a higher quality cable
• Reduce the circuit/components from 24 V to 5 V
• Add an external load at the input

Table A- 26

HSC clock input rates (max.)

Technical data

Single phase

Quadrature phase

CPU 1211C

100 KHz

80 KHz

CPU 1212C

100 KHz (Ia.0 to Ia.5) and
30 KHz (Ia.6 to Ia.7)

80 KHz (Ia.0 to Ia.5) and
20 KHz (Ia.6 to Ia.7)

CPU 1214C, CPU 1215C

100 KHz (Ia.0 to Ia.5) and
30 KHz (Ia.6 to Ib.5)

80 KHz (Ia.0 to Ia.5) and
20 KHz (Ia.6 to Ib.5)

CPU 1217C

1 MHz (DIb.2 to DIb.5)

High-speed (200 KHz) SB

200 kHz

160 kHz

Standard-speed SB

30 kHz

20 kHz

Logic 1 level = 15 to 26 VDC

A.4.2
Table A- 27

120/230 VAC digital AC inputs
120/230 VAC digital inputs

Technical data

Type

IEC Type 1

Rated voltage

120 VAC at 6 mA, 230 VAC at 9 mA

Continuous permissible voltage

264 VAC

Surge voltage

N/A

Logic 1 signal (min.)

79 VAC at 2.5 mA

Logic 0 signal (max.)

20 VAC at 1 mA

Leakage current (max.)

1 mA

Isolation (field side to logic)

1500 VAC for 1 minute

Isolation groups1

Input delay times

•

Typical: 0.2 to 12.8 ms, user selectable

•

Maximum: --

Connection of 2 wire proximity sensor (Bero) (max.)

1 mA

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A.4 Specifications for the digital inputs and outputs

Technical data

Cable length

Unshielded

300 meters

Shielded

500 meters

Number of inputs on simultaneously
1

Channels within a group must be of the same phase.

A.4.3
Table A- 28

Digital outputs (DQ)
Specifications for the digital outputs (DQ)

Technical data

Relay
(CPU and SM)

24 VDC
(CPU, SM, and SB)

200 KHZ 24 VDC
(SB)

Type

Relay, dry contact

Solid state - MOSFET
(Source)

Solid state - MOSFET
(Sink/Source)

Voltage range

5 to 30 VDC or
5 to 250 VAC

20.4 to 28.8 VDC

20.4 to 28.8 VDC 1
4.25 to 6.0 VDC 2

Logic 1 signal at max. current

N/A

20 VDC min.

L+ minus 1.5 V 1
L+ minus 0.7 V 2

CPU: 20 VDC min.,
0.1 VDC max.

1.0 VDC, max. 1
0.2 VDC, max. 2

Logic 0 signal with 10 KΩ load N/A

SB: 0.1 VDC max.
SM DC: 0.1 VDC max.
Current (max.)

2.0 A

0.5 A

0.1 A

Lamp load

30 W DC / 200 W AC

SB: 5 W

N/A

ON state resistance

0.2 Ω max. when new

0.6 Ω max.

11 Ω max. 1 or 7 Ω max. 2

OFF state resistance

N/A

6 Ω max. 1 or 0.2 Ω max. 2

Leakage current per point

N/A

10 μA max.

N/A

Pulse Train Output rate

CPU: N/A3

CPU: 100 KHz max.,2 Hz
min.4

200 kHz max., 2 Hz min.

SB: 20 KHz max., 2 Hz min.5
Surge current

7 A with contacts closed

CPU: 8 A for 100 ms max.

0.11 A

SB: 5 A for 100 ms max.
SM: 8 A for 100 ms max.
Overload protection

Isolation (field side to logic)

Coil to contact: 1500 VAC
for 1 minute

500 VAC for 1 minute

Coil to logic: None

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A.4 Specifications for the digital inputs and outputs

Technical data

Relay
(CPU and SM)

Isolation groups

•

24 VDC
(CPU, SM, and SB)

CPU 1211C: 1

•

CPU: 1

•

CPU 1212C: 2

•

SB: 1

•

CPU 1214C: 2

•

SM (DQ 8): 1

•

CPU 1215C: 2

•

SM (DQ 16): 1

•

SM DQ 8: 2

•

SM DQ 8 Changeover:8

•

SM DQ 16: 4

200 KHZ 24 VDC
(SB)
15

Isolation resistance

100 MΩ min. when new

N/A

Isolation between open
contacts

750 VAC for 1 minute

N/A

Current per common

CPU:

0.4 A

SM Relay:

•

SB: 1 A

•

SM DQ 8: 4 A

•

SM DQ 16: 8 A

•

SM 1222: 10 A (DQ 8
and DQ 16)

•

SM 1223 DI 8 / DQ 8
Relay: 10 A

•

SM 1223 DI 16 / DQ 16
Relay: 8 A

Inductive clamp voltage

N/A

L+ minus 48 V,
1 W dissipation

None

Maximum relay switching
frequency

1 Hz

N/A

Switching delay

10 ms max.

CPU:

1.5 μs + 300 s rise 1
1.5 μs + 300 ns fall 1

•

Qa.0 to Qa.3: 1.0 μs
max., off-to-on 3.0 μs
max., on-to-off

200 ns + 300 ns rise 2
200 ns + 300 ns fall 2

Qa.4 to Qb.1: 50 μs
max., off-to-on
200 μs max., on-to-off
SB: 2 μs max. off-to-on;
10 μs max. on-to-off
•

SM: 50 μs max. off-to-on
200 μs max. on-to-off
Lifetime mechanical (no load)

Relay: 10,000,000
open/close cycles

N/A

Lifetime contacts at rated load

Relay: 100,000 open/close
cycles

N/A

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A.5 Analog I/O modules

Technical data

Relay
(CPU and SM)

24 VDC
(CPU, SM, and SB)

200 KHZ 24 VDC
(SB)

Behavior on RUN to STOP

Last value or substitute
value (default value 0)

Cable length (meters)

500 m shielded,
150 m unshielded

50 m shielded twisted pair

24 VDC 200 KHz SB

5 VDC 200 KHz SB

For CPU models with relay outputs, you must install a digital signal board (SB) to use the pulse outputs.

Depending on your pulse receiver and cable, an additional load resistor (at least 10% of rated current) may improve
pulse signal quality and noise immunity.

SB 1223 200 KHz DI 2 / DQ 2: No isolation to inputs

A.5

Analog I/O modules
For a more complete list of modules available for S7-1200, refer to the S7-1200 System
Manual or to the customer support web site (http://www.siemens.com/automation/).

A.5.1
Table A- 29

SB 1231 and SB 1232 analog input (AI) and output (AQ)
General specifications

Technical data

SB 1231 AI 1 x12 bit 1

SB 1232 AQ 1 x 12 bit

Order number

6ES7 231-4HA30-0XB0

6ES7 232-4HA30-0XB0

Dimensions W x H x D (mm)

38 x 62 x 21 mm

Weight

35 grams

40 grams

Power dissipation

0.4 W

1.5 W

Current consumption (SM Bus)

55 mA

15 mA

Current consumption (24 VDC)

None

40 mA (no load)

Number of inputs / outputs

Type

Voltage or current (differential)

Voltage or current

To use the SB 1231 AI 1 x analog input, your CPU firmware must be V2.0 or higher.

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A.5 Analog I/O modules
Table A- 30

Wiring diagrams for the analog SBs
SB 1231 AI 1 x12 bit

SB 1232 AQ 1 x 12 bit

① Connect "R" and "0+" for current.

A.5.2
Table A- 31

SM 1231 analog input (AI)
SM 1231 analog inputs (AI)

Technical data

SM 1231 AI 4 x 13 bit

SM 1231 AI 8 x 13 bit

SM 1231 AI 4 x 16 bit

Order number (MLFB)

6ES7 231-4HD32-0XB0

6ES7 231-4HF32-0XB0

6ES7 231-5ND32-0XB0

Number of inputs

4 inputs (AI)

8 inputs (AI)

4 inputs

Type

Voltage or current
(differential), selectable in
groups of 2

Voltage or current
(differential)

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

180 grams

Power dissipation

1.5 W

1.8 W

Current consumption (SM Bus)

80 mA

90 mA

80 mA

Current consumption (24 VDC)

45 mA

65 mA

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A.5 Analog I/O modules

A.5.3
Table A- 32

SM 1232 analog output (AQ)
SM 1232 analog outputs (AQ)

Technical data

SM 1232 AQ 2 x 14 bit

SM 1232 AQ 4 x 14 bit

Order number (MLFB)

6ES7 232-4HB32-0XB0

6ES7 232-4HD32-0XB0

Number and type of outputs

2 outputs (AQ)

4 outputs (AQ)

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

180 grams

Power dissipation

1.5 W

Current consumption (SM Bus)

80 mA

Current consumption (24 VDC)

45 mA (no load)

A.5.4
Table A- 33

SM 1234 analog input/output (AI/AQ)
SM 1234 combination analog input / output (AI / AQ)

Technical data

SM 1234 AI 4 x 13 bit / AQ 2 x 14 bit

Order number (MLFB)

6ES7 234-4HE32-0XB0

Number of inputs

4 inputs (AI)

Type

Voltage or current (differential), selectable in groups of 2

Number of outputs

2 outputs (AQ)

Type

Voltage or current (differential)

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

220 grams

Power dissipation

2.0 W

Current consumption (SM Bus)

80 mA

Current consumption (24 VDC)

60 mA (no load)

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A.6 BB 1297 battery board

A.5.5
Table A- 34

Wiring diagrams for SM 1231 (AI), SM 1232 (AQ), and SM 1234 (AI/AQ)
Wiring diagrams for the analog SMs

SM 1231 AI 8 x 13 bit

SM 1232 AQ 4 x 13 bit

SM 1234 AI 4 x13 bit / AQ2 x 14 bit

Note
Unused voltage input channels should be shorted.
Unused current input channels should be set to the 0 to 20 mA range and/or disable broken
wire error reporting.
Inputs configured for current mode will not conduct loop current unless the module is
powered and configured.
Current input channels will not operate unless external power is supplied to the transmitter.

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A.6 BB 1297 battery board

A.6

BB 1297 battery board

BB 1297 Battery Board
Table A- 35

General specifications

Technical data

BB 1297 Battery

Order number

6ES7 297-0AX30-0XA0

Dimensions W x H x D (mm)

38 x 62 x 21

Weight

28 grams

Hold up time real time clock

Approximately 1 year

Type of battery

CR10251

"Maint" LED of the CPU

Indicating a battery replacement is needed

User program

Application / system can evaluate battery status

Refer to the S7-1200 Programmable Controller System Manual, Chapter 2, Installation for information about installing
the BB 1297 or replacing a battery in the BB.

The BB 1297 Battery board is used for applications where the real time clock retention time
is beyond one month. Features of the BB 1297 Battery board are shown below:
● Supports time of day clock during PLC power off. The S7-1200 CPU, in combination with
the BB 1297 Battery board, supports the Time of Day clock retention during a power off
period of the application for up to one year.
● Only one BB 1297 Battery board or other SB can be used at a time.
● Hot plugging / hot swapping is not allowed. The BB 1297 Battery board is only
exchangeable or pluggable while the CPU is powered off. While the CPU is powered off,
and the BB 1297 is removed to exchange the actual battery, the internal super cap will
hold the time of day while the user replaces the battery.
● The CPU "Maint" LED indicates when a replacement battery is needed.
● The user program allows you to monitor or check on the status of the battery, and battery
board and allows a user message to be displayed on an HMI or web server.

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A.7 Specifications for the analog I/O

A.7

Specifications for the analog I/O

A.7.1

Specifications for the analog inputs (CPU, SM, and SB)

Table A- 36

Specifications for analog inputs (AI)

Technical data

CPU

Type

Voltage (single-ended)

Voltage or current
(differential)

Voltage or current
(differential), selectable in
groups of 2

Range

0 to 10 V

±10 V, ±5 V, ±2.5,

±10 V, ±5 V, ±2.5 V,

0 to 20 mA, or

4 mA to 20 mA

Resolution

10 bits

11 bits + sign bit

12 bits + sign bit

Full scale range
(data word)

0 to 27648

-27,648 to 27,648

Accuracy
(25 °C / -20 to 60 °C)

3.0% / 3.5% of full-scale

±0.3% / ±0.6% of full scale

±0.1% / ±0.2% of full scale

Overshoot / undershoot range
(data word)

Voltage:
27,649 to 32,511

Voltage:
32,511 to 27,649 /
-27,649 to -32,512

Current: N/A

Current:
32,511 to 27,649 /
0 to -4864

Voltage:
32,512 to 32,767

Voltage:
32,767 to 32,512 /
-32,513 to -32,768

Current: N/A

Current:
32,767 to 32,512 /
-4865 to -32,768

Maximum withstand voltage /
current

35 VDC (voltage)

±35 V / ±40 mA

Smoothing
(See note 2)

None, weak, medium, or
strong

Noise rejection

10, 50, or 60 Hz

400, 60, 50, or 10 Hz

Measuring principle

Actual value conversion

Common mode rejection

40 dB, DC to 60 Hz

Operational signal range
(signal plus common mode
voltage)

Less than +12 V and
greater than 0 V

Less than +35 V and
greater than -35 V

Less than +12 V and greater
than -12 V

(See note 1)

Overflow / underflow (data
word)
(See note 1)

(See note 2)

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A.7 Specifications for the analog I/O

Technical data

CPU

Load impedance

Single-ended: ≥100 KΩ

Differential:
220 KΩ (voltage),
250 Ω (current)

Differential:
9 MΩ (voltage),
250 Ω (current)

Common mode:
55 KΩ (voltage),
55 KΩ (current)

Common mode:
4.5 MΩ (voltage),
4.5 MΩ (current)

None

Isolation (field side to logic)

None

Cable length (meters)

100 m, shielded twisted pair 100 m, twisted and shielded 100 m twisted and shielded

Diagnostics

Overflow / underflow

Overflow / underflow
24 VDC low voltage

Note 1: Refer to the analog input measurement ranges for voltage and current (Page 312) to determine the
overshoot/undershoot and overflow/underflow ranges.
Note 2: Refer to the step response times (Page 313) to determine the smoothing and noise rejection values.

A.7.2
Table A- 37

Input (AI) measurement ranges for voltage and current
Analog input representation for voltage (SB and SM)

System

Voltage Measuring Range

Decimal

Hexadecimal

±10 V

±5 V

±2.5 V

±1.25 V

32767

7FFF

11.851 V

5.926 V

2.963 V

1.481 V

Overflow

32512

7F00

32511

7EFF

11.759 V

5.879 V

2.940 V

1.470 V

Overshoot range

27649

6C01

27648

6C00

10 V

2.5 V

1.250 V

Rated range

20736

5100

7.5 V

3.75 V

1.875 V

0.938 V

361.7 μV

180.8 μV

90.4 μV

45.2 μV

-1

FFFF

-20736

AF00

-7.5 V

-3.75 V

-1.875 V

-0.938 V

-27648

9400

-10 V

-5 V

-2.5 V

-1.250 V

-27649

93FF

-32512

8100

-11.759 V

-5.879 V

-2.940 V

-1.470 V

-32513

80FF

-32768

8000

Undershoot range
Underflow
-11.851 V

-5.926 V

-2.963 V

-1.481 V

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A.7 Specifications for the analog I/O
Table A- 38

Analog input representation for current (SB and SM)
System

Current measuring range

Decimal

Hexadecimal

0 mA to 20 mA

4 mA to 20 mA

32767

7FFF

23.70 mA

22.96 mA

Overflow

32512

7F00

32511

7EFF

23.52 mA

22.81 mA

Overshoot range

27649

6C01

27648

6C00

20 mA

Nominal range

20736

5100

15 mA

16 mA

723.4 nA

4 mA + 578.7 nA

0 mA

4 mA

-1

FFFF

-4864

ED00

-3.52 mA

1.185 mA

-4865

ECFF

-32768

8000

Table A- 39

Undershoot range
Underflow

Analog input representation for voltage (CPU 1215C and CPU 1217C)

System

Voltage Measuring Range

Decimal

Hexadecimal

0 to 10 V

32767

7FFF

11.851 V

Overflow

32512

7F00

32511

7EFF

11.759 V

Overshoot range

27649

6C01

27648

6C00

10 V

Rated range

20736

5100

7.5 V

12 mV

Negative values

A.7.3

Negative values are not
supported

Step response for the analog inputs (AI)
The following table shows the step response times for the analog inputs (AI) of the CPU, SB
and SM.

Table A- 40

Step response (ms) for the analog inputs

Smoothing selection (sample averaging)

Integration time selection
400 Hz (2.5 ms)

None (1 cycle):
No averaging

60 Hz (16.6 ms)

50 Hz (20 ms)

10 Hz (100 ms)

CPU

N/A

130

4.5

18.7

22.0

102

100

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A.7 Specifications for the analog I/O

Smoothing selection (sample averaging)

Integration time selection
400 Hz (2.5 ms)

Weak (4 cycles):
4 samples
Medium (16 cycles):
16 samples
Strong (32 cycles):
32 samples
Sample rate

A.7.4
Table A- 41

50 Hz (20 ms)

10 Hz (100 ms)

N/A

340

10.6

59.3

70.8

346

320

CPU

N/A

221

258

1210

33.0

208

250

1240

203

241

1200

CPU

N/A

424

499

2410

63.0

408

490

2440

400

483

2410

CPU

N/A

4.17

0.156

1.042

1.250

6.250

Sample time and update times for the analog inputs
Sample time and update time for SM and CPU

Rejection frequency
(Integration time)

60 Hz (16.6 ms)

CPU

Sample time

Update time for all channels
4-channel SM

8-channel SM

CPU AI

400 Hz (2.5 ms)

0.625 ms 1

2.5 ms

10 ms

N/A ms

60 Hz (16.6 ms)

4.170 ms

4.17 ms

50 Hz (20 ms)

5.000 ms

5 ms

10 Hz (100 ms)

25.000 ms

25 ms

Sample rate for 8-channel SM is 1.250 ms.

Table A- 42

Sample time and update time for SB
Sample time

SB update time

400 Hz (2.5 ms)

Rejection frequency (Integration time)

0.156 ms

60 Hz (16.6 ms)

1.042 ms

50 Hz (20 ms)

1.250 ms

1.25 ms

10 Hz (100 ms)

6.250 ms

6.25 ms

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A.7 Specifications for the analog I/O

A.7.5
Table A- 43

Specifications for the analog outputs
Specifications for the analog outputs (SB and SM)

Technical data

Type

Voltage or current

Range

±10 V, 0 to 20 mA, or 4 to 20 mA

Resolution

Voltage: 12 bits

Voltage: 14 bits

Current: 11 bits

Current: 13 bits

Voltage: -27,648 to 27,648

Current: 0 to 27,648

Accuracy
(25 °C / -20 to 60 °C)

±0.5% / ±1% of full scale

±0.3% / ±0.6% of full scale

Settling time
(95% of new value)

Voltage: 300 μS (R), 750 μS (1 uF)

Current: 600 μS (1 mH), 2 ms (10 mH)

Load impedance

Voltage: ≥ 1000 Ω

Current: ≤ 600 Ω

Behavior on RUN to STOP

Last value or substitute value (default
value 0)

Isolation
(field side to logic)

None

Cable length (meters)

100 m, twisted and shielded

Diagnostics

•

Overflow / underflow

•

Overflow / underflow

•

Short to ground (voltage mode only)

•

Short to ground (voltage mode only)

•

Wire break (current mode only)

•

Wire break (current mode only)

•

24 VDC low voltage

Full scale range
(data word)
(See note 1)

Note 1: Refer to the output ranges for voltage and current (Page 315) for the full-scale range.

A.7.6
Table A- 44

Output (AQ) measurement ranges for voltage and current
Analog output representation for voltage (SB and SM)
System

Voltage Output Range

Decimal

Hexadecimal

± 10 V

32767

7FFF

See note 1

32512

7F00

See note 1

32511

7EFF

11.76 V

Overshoot range

27649

6C01

27648

6C00

10 V

Rated range

20736

5100

7.5 V

361.7 μ V

Overflow

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A.7 Specifications for the analog I/O

System

Voltage Output Range

Decimal

Hexadecimal

± 10 V

-1

FFFF

-361.7 μ V

-20736

AF00

-7.5 V

-27648

9400

-10 V

-27649

93FF

-32512

8100

-11.76 V

-32513

80FF

See note 1

-32768

8000

See note 1

Undershoot range
Underflow

In an overflow or underflow condition, analog outputs will take on the substitute value of the STOP mode.

Table A- 45

Analog output representation for current (SB and SM)
System

Current output range

Decimal

Hexadecimal

0 mA to 20 mA

4 mA to 20 mA

32767

7FFF

See note 1

32512

7F00

See note 1

32511

7EFF

23.52 mA

22.81 mA

Overshoot range

27649

6C01

27648

6C00

20 mA

Rated range

20736

5100

15 mA

16 mA

723.4 nA

4 mA + 578.7 nA

0 mA

4mA

-1

FFFF

4 mA to 578.7 nA

-6912

E500

0 mA

-6913

E4FF

-32512

8100

-32513

80FF

See note 1

-32768

8000

See note 1

Overflow

Undershoot range
Not possible. Output value limited to 0 mA.
Underflow

In an overflow or underflow condition, analog outputs will take on the substitute value of the STOP mode.

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A.8 RTD and Thermocouple modules
Table A- 46

Analog output representation for current (CPU 1215C and CPU 1217C)
System

Decimal

Hexadecimal

0 mA to 20 mA

32767

7FFF

See note 1

32512

7F00

See note 1

32511

7EFF

23.52 mA

Overshoot range

27649

6C01

27648

6C00

20 mA

Rated range

20736

5100

15 mA

12 mV

0 mA

Negative values
1

Current output range
Overflow

Negative values are not
supported

In an overflow condition, analog outputs will behave according to the device configuration properties settings. In the
"Reaction to CPU STOP" parameter, select either: "Use substitute value" or "Keep last value".

A.8

RTD and Thermocouple modules
The thermocouple (TC) modules (SB 1231 TC and SM 1231 TC) measure the value of
voltage connected to the analog inputs. This value can be either temperature from a TC or
volts.
● If voltage, the nominal range full scale value will be decimal 27648.
● If temperature, the value will be reported in degrees multiplied by ten (for example, 25.3
degrees will be reported as decimal 253).
The RTD modules (SB 1231 RTD and SM 1231 RTD) measure the value of resistance
connected to the analog inputs. This value can be either temperature or resistance.
● If resistance, the nominal range full scale value will be decimal 27648.
● If temperature, the value will be reported in degrees multiplied by ten (for example, 25.3
degrees will be reported as decimal 253).
The RTD modules support measurements with 2-wire, 3-wire and 4-wire connections to the
sensor resistor.
Note
The RTD and TC modules report 32767 on any activated channel with no sensor connected.
If open wire detection is also enabled, the module flashes the appropriate red LEDs.
Best accuracy will be achieved for the 10 Ω RTD ranges if 4 wire connections are used.
The resistance of the connection wires in 2 wire mode will cause an error in the sensor
reading, and therefore accuracy is not guaranteed.

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A.8 RTD and Thermocouple modules
Note
After power is applied, the module performs internal calibration for the analog-to-digital
converter. During this time the module reports a value of 32767 on each channel until valid
data is available on that channel. Your user program may need to allow for this initialization
time. Because the configuration of the module can vary the length of the initialization time,
you should verify the behavior of the module in your configuration. If required, you can
include logic in your user program to accommodate the initialization time of the module.

A.8.1

SB 1231 RTD and SB 1231 TC specifications
Note
To use these TC and RTD SBs, your CPU firmware must be V2.0 or higher.

Table A- 47

General specifications

Technical data

SB 1231 AI 1 x16 bit TC

SB 1231 AI 1 x 16 bit RTD

Order number

6ES7 231-5QA30-0XB0

6ES7 231-5PA30-0XB0

Dimensions W x H x D (mm)

38 x 62 x 21 mm

Weight

35 grams

Power dissipation

0.5 W

0.7 W

Current consumption (SM Bus)

5 mA

Current consumption (24 VDC)

20 mA

25 mA

Number of inputs (Page 323)

Type

Floating TC and mV

Module-referenced RTD and Ω

Diagnostics

•
•

Overflow / underflow1, 2
Wire

break3

•

Overflow / underflow1, 2

•

Wire break3

The overflow and underflow diagnostic alarm information will be reported in the analog data values even if the alarms
are disabled in the module configuration.

RTD: For resistance ranges, underflow detection is never enabled.

When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.

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A.8 RTD and Thermocouple modules
Table A- 48

Wiring diagrams for SB 1231 TC and RTD
SB 1231 AI 1 x 16 bit TC

SB 1231 AI 1 x 16 bit RTD

① Loop-back unused RTD input
② 2-wire RTD ③ 3-wire RTD ④ 4-wire RTD

A.8.2
Table A- 49

SM 1231 RTD specifications
General specifications

Technical data

SM 1231 AI 4 x RTD x 16 bit

SM 1231 AI 8 x RTD x 16 bit

Order number

6ES7 231-5PD32-0XB0

6ES7 231-5PF32-0XB0

Dimensions
W x H x D (mm)

45 x 100 x 75

70 x 100 x 75

Weight

220 grams

270 grams

Power dissipation

1.5 W

Current consumption
(SM Bus)

80 mA

90 mA

Current consumption 1
(24 VDC)

40 mA

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A.8 RTD and Thermocouple modules

Technical data

SM 1231 AI 4 x RTD x 16 bit

SM 1231 AI 8 x RTD x 16 bit

Number of inputs (Page 323)

Type

Module-referenced RTD and Ω

Diagnostics

•

Overflow / underflow

•
•

Module-referenced RTD and Ω
•

Overflow / underflow 2,3

24 VDC low voltage 2

•

24 VDC low voltage 2

Wire break (current mode only) 4

•

Wire break (current mode only) 4

2,3

20.4 to 28.8 VDC (Class 2, Limited Power, or sensor power from CPU)

The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
the alarms are disabled in the module configuration.

For resistance ranges underflow detection is never enabled.

When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.

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A.8 RTD and Thermocouple modules
Table A- 50

Wiring diagrams for the RTD SMs

SM 1231 RTD 4 x 16 bit

SM 1231 RTD 8 x 16 bit

① Loop-back unused RTD inputs
② 2-wire RTD
③ 3-wire RTD
④ 4-wire RTD
Note: Connectors must be gold. See the S7-1200 Programmable controller system manual, Appendix C.

A.8.3
Table A- 51

SM 1231 TC specifications
General specifications

Model

SM 1231 AI 4 x 16 bit TC

SM 1231 AI 8 x 16 bit TC

Order number

6ES7 231-5QD32-0XB0

6ES7 231-5QF32-0XB0

Dimensions
W x H x D (mm)

45 x 100 x 75

Weight

180 grams

xxx grams

Power dissipation

1.5 W

Current consumption
(SM Bus)

80 mA

Current consumption 1
(24 VDC)

40 mA

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A.8 RTD and Thermocouple modules

Model

SM 1231 AI 4 x 16 bit TC

SM 1231 AI 8 x 16 bit TC

Number of inputs (Page 323)

Type

Floating TC and mV

Diagnostics

•

Overflow / underflow

•
•

Floating TC and mV
•

Overflow / underflow 2

24 VDC low voltage 2

•

24 VDC low voltage 2

Wire break (current mode only) 3

•

Wire break (current mode only) 3

20.4 to 28.8 VDC (Class 2, Limited Power, or sensor power from CPU)

The overflow, underflow and low voltage diagnostic alarm information will be reported in the analog data values even if
the alarms are disabled in the module configuration.

When wire break alarm is disabled and an open wire condition exists in the sensor wiring, the module may report
random values.

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A.8 RTD and Thermocouple modules
Table A- 52

Wiring diagrams for the TC SMs

SM 1231 AI 4 x 16 bit TC

SM 1231 AI 8 x 16 bit TC

① SM 1231 AI 8 TC: For clarity, TC 2, 3, 4, and 5 are not shown connected.

A.8.4
Table A- 53

Analog input specifications for RTD and TC (SM and SB)
Analog inputs for the RTD and TC modules (SB and SM)

Technical data

RTD and Thermocouple (TC)

Number of inputs

1 (SB), 4 or 8 (SM)

Type

•

RTD: Module referenced RTD and Ω

•

TC: Floating TC and mV

Range

See the RTD/TC type tables:

•

Nominal range (data word)

•

RTD (Page 326)

•

Overshoot/undershoot range (data word)

•

TC (Page 324)

•

Overflow/underflow (data word)

Resolution

Temperature

0.1 °C / 0.1 °F

Resistance / voltage

15 bits plus sign

Maximum withstand voltage

± 35 V

Noise rejection

85 dB for the selected filter setting
(10 Hz, 50 Hz, 60 Hz or 400 Hz)

Common mode rejection

> 120 dB at 120 VAC

Impedance

≥ 10 MΩ

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A.8 RTD and Thermocouple modules

Technical data
Isolation

RTD and Thermocouple (TC)
Field side to logic

500 VAC

Field to 24 VDC

SM RTD and SM TC: 500 VAC
(Not applicable for SB RTD and SB TC)

24 VDC to logic

SM RTD and SM TC: 500 VAC
(Not applicable for SB RTD and SB TC)

Channel to channel isolation

Accuracy (25 °C / -20 to 60 °C)

•

SM RTD: None
(Not applicable for SB RTD)

•

SM TC: 120 VAC
(Not applicable for SB TC)

See the RTD/TC type tables:
•

RTD (Page 326)

•

TC (Page 324)

Repeatability

±0.05% FS

Maximum sensor dissipation

•

RTD: 0.5 mW

•

TC: Not applicable

Measuring principle

Integrating

Module update time

See the RTD/TC filter selection tables:

Cold junction error

•

RTD (Page 327)

•

TC (Page 325)

•

RTD: Not applicable

•

TC: ±1.5 °C

Cable length (meters)

100 meters to sensor max.

Wire resistance

•

RTD: 20 Ω, 2.7 Ω for 10 Ω RTD max.

•

TC: 100 Ω max.

A.8.5
Table A- 54

Thermocouple type
Thermocouple type (ranges and accuracy)

Type

Under range
minimum1

Nominal
Nominal
range low limit range high
limit

Over range Normal range 3,
maximum2 4 accuracy
@ 25 °C

Normal range 3, 4
accuracy
-20 °C to 60 °C

-210.0 °C

-150.0 °C

1200.0 °C

1450.0 °C

±0.3 °C

±0.6 °C

-270.0 °C

-200.0 °C

1372.0 °C

1622.0 °C

±0.4 °C

±1.0 °C

-270.0 °C

-200.0 °C

400.0 °C

540.0 °C

±0.5 °C

±1.0 °C

-270.0 °C

-200.0 °C

1000.0 °C

1200.0 °C

±0.3 °C

±0.6 °C

R&S

-50.0 °C

100.0 °C

1768.0 °C

2019.0 °C

±1.0 °C

±2.5 °C

0.0 °C

200.0 °C

800.0 °C

±2.0 °C

±2.5 °C

800.0 °C

1820.0 °C

±1.0 °C

±2.3 °C

-270.0 °C

-200.0 °C

1300.0 °C

1550.0 °C

±1.0 °C

±1.6 °C

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A.8 RTD and Thermocouple modules

Type

Under range
minimum1

Nominal
Nominal
range low limit range high
limit

Over range
maximum2

Normal range 3,
4 accuracy
@ 25 °C

Normal range 3, 4
accuracy
-20 °C to 60 °C

0.0 °C

100.0 °C

2315.0 °C

2500.0 °C

±0.7 °C

±2.7 °C

TXK / XK(L)

-200.0 °C

-150.0 °C

800.0 °C

1050.0 °C

±0.6 °C

±1.2 °C

Voltage

-32512

-27648
-80 mV

27648
80 mV

32511

±0.05%

±0.1%

Thermocouple values below the under-range minimum value are reported as -32768.

Thermocouple values above the over-range minimum value are reported as 32767.

Internal cold junction error is ±1.5 °C for all ranges. This adds to the error in this table. The module requires at least 30
minutes of warm-up time to meet this specification.

For the 4-channel SM TC only: In the presence of radiated radio frequency of 970 MHz to 990 MHz, the accuracy may
be degraded.

Note
Thermocouple channel
Each channel on the Thermocouple signal module can be configured with a different
thermocouple type (selectable in the software during configuration of the module).

A.8.6

Thermocouple filter selection and update times
For measuring thermocouples, it is recommended that a 100 ms integration time be used.
The use of smaller integration times will increase the repeatability error of the temperature
readings.

Table A- 55

Thermocouple filter selection and update times

Rejection frequency
(Hz)

Integration time
(ms)

Update time (seconds)
1-channel SB

4-channel SM

8-channel SM

100

0.301

1.225

2.450

0.061

0.263

0.525

16.67

0.051

0.223

0.445

4001

0.031

0.143

0.285

To maintain module resolution and accuracy when 400 Hz rejection is selected, the integration time is 10 ms. This
selection also rejects 100 Hz and 200 Hz noise.

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A.8 RTD and Thermocouple modules

A.8.7
Table A- 56

RTD sensor type selection table
Ranges and accuracy for the different sensors supported by the RTD modules

Temperature
coefficient

Pt 0.003850
ITS90
DIN EN 60751

RTD type

Under range
minimum1

Nominal
range
low limit

Nominal
range
high limit

Over
range
maximu
m2

Normal
range
accuracy @
25 °C

Normal range
accuracy
-20 °C to
60 °C

Pt 100
climatic

-145.00 °C

-120.00 °C

145.00 °C

155.00 °
C

±0.20 °C

±0.40 °C

Pt 10

-243.0 °C

-200.0 °C

850.0 °C

1000.0 °
C

±1.0 °C

±2.0 °C

Pt 50

-243.0 °C

-200.0 °C

850.0 °C

1000.0 °
C

±0.5 °C

±1.0 °C

Pt 100

-243.0 °C

-200.0 °C

850.0 °C

1000.0 °
C

± 0.5 °C

±1.0 °C

Pt 200

-243.0 °C

-200.0 °C

850.0 °C

1000.0 °
C

± 0.5 °C

±1.0 °C

Pt 10

-273.2 °C

-240.0 °C

1100.0 °C

1295 °C

±1.0 °C

±2.0 °C

Pt 50

-273.2 °C

-240.0 °C

1100.0 °C

1295 °C

±0.8 °C

±1.6 °C

-105.0 °C

-60.0 °C

250.0 °C

295.0 °C

±0.5 °C

±1.0 °C

Pt 100
Pt 200
Pt 500
Pt 1000
Pt 0.003902
Pt 0.003916
Pt 0.003920

Pt 500
Pt 1000
Pt 0.003910

Pt 100
Pt 500
Ni 0.006720
Ni 0.006180

Ni 100
Ni 120
Ni 200
Ni 500
Ni 1000

LG-Ni 0.005000

LG-Ni 1000

-105.0 °C

-60.0 °C

250.0 °C

295.0 °C

±0.5 °C

±1.0 °C

Ni 0.006170

Ni 100

-105.0 °C

-60.0 °C

180.0 °C

212.4 °C

±0.5 °C

±1.0 °C

Cu 0.004270

Cu 10

-240.0 °C

-200.0 °C

260.0 °C

312.0 °C

±1.0 °C

±2.0 °C

Cu 0.004260

Cu 10

-60.0 °C

-50.0 °C

200.0 °C

240.0 °C

±1.0 °C

±2.0 °C

Cu 50

-60.0 °C

-50.0 °C

200.0 °C

240.0 °C

±0.6 °C

±1.2 °C

Cu 10

-240.0 °C

-200.0 °C

200.0 °C

240.0 °C

±1.0 °C

±2.0 °C

Cu 50

-240.0 °C

-200.0 °C

200.0 °C

240.0 °C

±0.7 °C

±1.4 °C

Cu 100
Cu 0.004280

Cu 100
1

RTD values below the under-range minimum value are reported as -32768.

RTD values above the over-range maximum value are reported as +32767.

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A.8 RTD and Thermocouple modules
Table A- 57
Range

Under range
minimum

Nominal range
low limit

Nominal range
high limit

Over
range
maximum1

Normal range
accuracy
@ 25 °C

Normal range
accuracy
-20 °C to 60 °C

150 Ω

n/a

0 (0 Ω)

27648 (150 Ω)

176.383 Ω

±0.05%

±0.1%

300 Ω

n/a

0 (0 Ω)

27648 (300 Ω)

352.767 Ω

±0.05%

±0.1%

600 Ω

n/a

0 (0 Ω)

27648 (600 Ω)

705.534 Ω

±0.05%

±0.1%

Resistance values above the over-range maximum value are reported as 32767.

A.8.8

RTD filter selection and update times

Table A- 58

Resistance

Filter selection and update times

Noise rejection
frequency (Hz)

Integration time
(ms)

100

16.67

4001

Update time (seconds)
1-channel SB

4-channel SM

8-channel SM

4-/2-wire: 0.301

4-/2-wire: 1.222

4-/2-wire: 2.445

3-wire: 0.601

3-wire: 2.445

3-wire: 4.845

4-/2-wire: 0.061

4-/2-wire: 0.262

4-/2-wire: 0.525

3-wire: 0.121

3-wire: .505

3-wire: 1.015

4-/2-wire: 0.051

4-/2-wire: 0.222

4-/2-wire: 0.445

3-wire: 0.101

3-wire: 0.424

3-wire: 0.845

4-/2-wire: 0.031

4-/2-wire: 0.142

4-/2-wire: 0.285

3-wire: 0.061

3-wire: 0.264

3-wire: 0.525

To maintain module resolution and accuracy when the 400 Hz filter is selected, the integration time is 10 ms. This
selection also rejects 100 Hz and 200 Hz noise.

Note
The module reports 32767 on any activated channel with no sensor connected. If open wire
detection is also enabled, the module flashes the appropriate red LEDs.
Best accuracy will be achieved for the 10 Ω RTD ranges if 4 wire connections are used.
The resistance of the connection wires in 2 wire mode will cause an error in the sensor
reading and therefore accuracy is not guaranteed.

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Technical specifications
A.9 Communication interfaces

A.9

Communication interfaces
For a more complete list of modules available for S7-1200, refer to the S7-1200 System
Manual or to the customer support web site (http://www.siemens.com/automation/).

A.9.1

PROFIBUS master/slave

A.9.1.1

CM 1242-5 PROFIBUS slave

Table A- 59

Technical specifications of the CM 1242-5

Technical specifications
Order number

6GK7 242-5DX30-0XE0

Interfaces
Connection to PROFIBUS

9-pin D-sub female connector

Maximum current consumption on the PROFIBUS interface
when network components are connected (for example
optical network components)

15 mA at 5 V (only for bus termination) *)

Permitted ambient conditions
Ambient temperature
•

during storage

•

-40 °C to 70 °C

•

during transportation

•

-40 °C to 70 °C

•

during operation with a vertical installation (DIN rail
horizontal)

•

0 °C to 55 °C

•

during operation with a horizontal installation (DIN rail
vertical)

•

0 °C to 45 °C

Relative humidity at 25 °C during operation, without
condensation, maximum

95 %

Degree of protection

IP20

Power supply, current consumption and power loss
Type of power supply

Power supply from the backplane bus

Current consumption (typical)

150 mA

Effective power loss (typical)

0.75 W

Dimensions and weights
•

Width

•

30 mm

•

Height

•

100 mm

•

Depth

•

75 mm

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A.9 Communication interfaces

Technical specifications
Weight
•

Net weight

•

115 g

•

Weight including packaging

•

152 g

*)The current load of an external consumer connected between VP (pin 6) and DGND (pin 5) must not exceed a maximum
of 15 mA (short-circuit proof) for bus termination.

PROFIBUS interface
Table A- 60

Pinout of the D-sub socket

A.9.1.2
Table A- 61

Description

- not used -

P5V2: +5V power supply

- not used -

RxD/TxD-P: Data line B

RxD/TxD-N: Data line A

RTS

- not used -

M5V2: Data reference potential
(ground DGND)

Housing

Ground connector

CM 1243-5 PROFIBUS master
Technical specifications of the CM 1243-5

Technical specifications
Order number

6GK7 243-5DX30-0XE0

Interfaces
Connection to PROFIBUS

9-pin D-sub female connector

Maximum current consumption on the PROFIBUS interface
when network components are connected (for example
optical network components)

15 mA at 5 V (only for bus termination) *)

Permitted ambient conditions
Ambient temperature
•

during storage

•

-40 °C to 70 °C

•

during transportation

•

-40 °C to 70 °C

•

during operation with a vertical installation (DIN rail
horizontal)

•

0 °C to 55 °C

•

during operation with a horizontal installation (DIN rail
vertical)

•

0 °C to 45 °C

Relative humidity at 25 °C during operation, without
condensation, maximum

95 %

Degree of protection

IP20

Power supply, current consumption and power loss
Type of power supply

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A.9 Communication interfaces

Technical specifications
Power supply / external

24 V

•

minimum

•

19.2 V

•

maximum

•

28.8 V

Current consumption (typical)
•

from 24 V DC

•

100 mA

•

from the S7-1200 backplane bus

•

0 mA

Effective power loss (typical)
•

from 24 V DC

•

2.4 W

•

from the S7-1200 backplane bus

•

Power supply 24 VDC / external
•

Min. cable cross section

•

min.: 0.14 mm2 (AWG 25)

•

Max. cable cross section

•

max.: 1.5 mm2 (AWG 15)

•

Tightening torque of the screw terminals

•

0.45 Nm (4 lb-in)

Dimensions and weights
•

Width

•

30 mm

•

Height

•

100 mm

•

Depth

•

75 mm

Weight
•

Net weight

•

134 g

•

Weight including packaging

•

171 g

*)The current load of an external consumer connected between VP (pin 6) and DGND (pin 5) must not exceed a maximum
of 15 mA (short-circuit proof) for bus termination.

PROFIBUS interface
Table A- 62
Pin

Pinout of the D-sub socket
Description

Description

- not used -

VP: Power supply +5 V only for bus
terminating resistors;
not for supplying external devices

- not used -

RxD/TxD-P: Data line B

RxD/TxD-N: Data line A

CNTR-P: RTS

- not used -

DGND: Ground for data signals
and VP

Housing

Ground connector

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A.9 Communication interfaces

PROFIBUS cable
Note
Contacting the shield of the PROFIBUS cable
The shield of the PROFIBUS cable must be contacted.
To do this, strip the insulation from the end of the PROFIBUS cable and connect the shield
to functional earth.

A.9.2

GPRS CP
Note
The GPRS CP is not approved for Maritime applications
The following module does not have Maritime approval:
• CP 1242-7 GPRS module
Note
To use these modules, your CPU firmware must be V2.0 or higher.

A.9.2.1
Table A- 63

Technical specifications of the CP 1242-7 GPRS
Technical specifications of the CP 1242-7

Technical specifications
Order number

6GK7 242-7KX30-0XE0

Wireless interface
Antenna connector

SMA socket

Nominal impedance

50 ohms

Wireless connection
Maximum transmit power

•

GSM 850, class 4: +33 dBm ±2dBm

•

GSM 900, class 4: +33 dBm ±2dBm

•

GSM 1800, class 1: +30 dBm ±2dBm

•

GSM 1900, class 1: +30 dBm ±2dBm

GPRS

Multislot class 10
device class B
coding scheme 1...4 (GMSK)

SMS

Mode outgoing: MO
service: point-to-point

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A.9 Communication interfaces

Technical specifications
Permitted ambient conditions
Ambient temperature
•

during storage

•

-40 °C to 70 °C

•

during transportation

•

-40 °C to 70 °C

•

during operation with a vertical installation (DIN rail
horizontal)

•

0 °C to 55 °C

•

during operation with a horizontal installation (DIN rail
vertical)

•

0 °C to 45 °C

Relative humidity at 25 °C during operation, without
condensation, maximum

95 %

Degree of protection

IP20

Power supply, current consumption and power loss
Type of power supply

Power supply / external

24 V

•

minimum

•

19.2 V

•

maximum

•

28.8 V

Current consumption (typical)
•

from 24 V DC

•

100 mA

•

from the S7-1200 backplane bus

•

0 mA

Effective power loss (typical)
•

from 24 V DC

•

2.4 W

•

from the S7-1200 backplane bus

•

24 V DC power supply
•

Min. cable cross section

•

min.: 0.14 mm2 (AWG 25)

•

Max. cable cross section

•

max.: 1.5 mm2 (AWG 15)

•

Tightening torque of the screw terminals

•

0.45 Nm (4 lb-in)

Electrical isolation

710 VDC for 1 minute

Power supply unit to internal circuit
Dimensions and weights
•

Width

•

30 mm

•

Height

•

100 mm

•

Depth

•

75 mm

Weight
•

Net weight

•

133 g

•

Weight including packaging

•

170 g

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A.9 Communication interfaces

Technical specifications of the ANT794-4MR GSM/GPRS antenna
ANT794-4MR
Order number

6NH9860-1AA00

Mobile wireless networks

GSM/GPRS

Frequency ranges

•

824 to 960 MHz (GSM 850, 900)

•

1 710 to 1 880 MHz (GSM 1 800)

•

1 900 to 2 200 MHz (GSM / UMTS)

Characteristics

omnidirectional

Antenna gain

0 dB

Impedance

50 ohms

Standing wave ratio (SWR)

< 2,0

Max. power

20 W

Polarity

linear vertical

Connector

SMA

Length of antenna cable

External material

Hard PVC, UV-resistant

Degree of protection

IP20

Permitted ambient conditions
•

Operating temperature

•

-40 °C through +70 °C

•

Transport/storage temperature

•

-40 °C through +70 °C

•

Relative humidity

•

100 %

External material

Hard PVC, UV-resistant

Construction

Antenna with 5 m fixed cable and SMA male
connector

Dimensions (D x H) in mm

25 x 193

Weight
•

Antenna incl. cable

•

310 g

•

Fittings

•

54 g

Installation

With supplied bracket

Technical specifications of the flat antenna ANT794-3M
Order number

6NH9870-1AA00

Mobile wireless networks

GSM 900

GSM 1800/1900

Frequency ranges

890 - 960 MHz

1710 - 1990 MHz

Standing wave ratio (VSWR)

≤ 2:1

≤ 1,5:1

Return loss (Tx)

≈ 10 dB

≈ 14 dB

Antenna gain

0 dB

Impedance

50 ohms

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Technical specifications
A.9 Communication interfaces

A.9.3

Max. power

10 W

Antenna cable

HF cable RG 174 (fixed) with SMA male connector

Cable length

1.2 m

Degree of protection

IP64

Permitted temperature range

-40°C to +75°C

Flammability

UL 94 V2

External material

ABS Polylac PA-765, light gray (RAL 7035)

Dimensions (W x L x H) in mm

70.5 x 146.5 x 20.5

Weight

130 g

Teleservice (TS)
The following manuals contain the technical specification for the TS Adapter IE Basic and
the TS Adapter modular:
● Industrial Software Engineering Tools
Modular TS Adapter
● Industrial Software Engineering Tools
TS Adapter IE Basic
For more information about this product and for the product documentation, refer to the
product catalog web site for the TS Adapter.

A.9.4

RS485, RS232 and RS422 communication

A.9.4.1

CB 1241 RS485 specifications
Note
To use this CB, your CPU firmware must be V2.0 or higher.

Table A- 64

General specifications

Technical data

CB 1241 RS485

Order number

6ES7 241-1CH30-1XB0

Dimensions W x H x D (mm)

38 x 62 x 21

Weight

40 grams

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A.9 Communication interfaces
Table A- 65

Transmitter and receiver

Technical data

CB 1241 RS485

Type

RS485 (2-wire half-duplex)

Common mode voltage range

-7 V to +12 V, 1 second, 3 VRMS continuous

Transmitter differential output voltage

2 V min. at RL = 100 Ω
1.5 V min. at RL = 54 Ω

Termination and bias

10K to +5 V on B, RS485 Pin 3
10K to GND on A, RS485 Pin 4

Optional termination

Short Pin TB to Pin T/RB, effective termination impedance is 127 Ω,
connects to RS485 Pin 3
Short Pin TA to Pin T/RA, effective termination impedance is 127 Ω,
connects to RS485 Pin 4

Receiver input impedance

5.4K Ω min. including termination

Receiver threshold/sensitivity

+/- 0.2 V min., 60 mV typical hysteresis

Isolation
RS485 signal to chassis ground
RS485 signal to CPU logic common

500 VAC, 1 minute

Cable length, shielded

1000 m max.

Baud rate

300 baud, 600 baud, 1.2 kbits, 2.4 kbits, 4.8 kbits, 9.6 kbits (default),
19.2 kbits, 38.4 kbits, 57.6 kbits, 76.8 kbits, 115.2 kbits,

Parity

No parity (default), even, odd, Mark (parity bit always set to 1),
Space (parity bit always set to 0)

Number of stop bits

1 (default), 2

Flow control

Not supported

Wait time

0 to 65535 ms

Table A- 66

Power supply

Technical data

CB 1241 RS485

Power loss (dissipation)

1.5 W

Current consumption (SM Bus), max.

50 mA

Current consumption (24 VDC) max.

80 mA

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A.9 Communication interfaces

CB 1241 RS485 (6ES7 241-1CH30-1XB0)

① Connect "TA" and TB" as shown to terminate the network. (Terminate only the end devices on the RS485 network.)
② Use shielded twisted pair cable and connect the cable shield to ground.
You terminate only the two ends of the RS485 network. The devices in between the two end
devices are not terminated or biased. See the S7-1200 System Manual section on "Biasing
and terminating an RS485 network connector"
Table A- 67
Pin

Connector pin locations for CB 1241 RS485 (6ES7 241-1CH30-1XB0)

9-Pin connector

X20

RS485 / Logic GND

RS485 / Not Used

RS485 / TxD+

3 - T/RB

RS485 / RTS

1 - RTS

RS485 / Logic GND

RS485 / 5 V Power

RS485 / Not used

RS485 / TxD-

4 - T/RA

RS485 / Not Used

Shell

7-M

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A.9 Communication interfaces

A.9.4.2

CM 1241 RS422/485 specifications

CM 1241 RS422/485 Specifications
Table A- 68

General specifications

Technical data

CM 1241 RS422/485

Order number

6ES7 241-1CH32-0XB0

Dimensions W x H x H (mm)

30 x 100 x 75

Weight

155 grams

Table A- 69

Transmitter and receiver

Technical data

CM 1241 RS422/485

Type

RS422 or RS485, 9-pin sub D female connector

Common mode voltage range

-7 V to +12 V, 1 second, 3 VRMS continuous

Transmitter differential output voltage

2 V min. at RL = 100 Ω
1.5 V min. at RL = 54 Ω

Termination and bias

10K Ω to +5 V on B, PROFIBUS Pin 3
10K Ω to GND on A, PROFIBUS Pin 8
Internal bias options provided, or no internal bias. In all cases,
external termination is required, see Biasing and terminating an
RS485 network connector and Configuring the RS422 and RS485 in
the S7-1200 System Manual

Receiver input impedance

5.4K Ω min. including termination

Receiver threshold/sensitivity

+/- 0.2 V min., 60 mV typical hysteresis

Isolation
RS485 signal to chassis ground
RS485 signal to CPU logic common

500 VAC, 1 minute

Cable length, shielded

1000 m max. (baud rate dependent)

Baud rate

300 baud, 600 baud, 1.2 kbits, 2.4 kbits, 4.8 kbits, 9.6 kbits (default),
19.2 kbits, 38.4 kbits, 57.6 kbits, 76.8 kbits, 115.2 kbits,

Parity

No parity (default), even, odd, Mark (parity bit always set to 1),
Space (parity bit always set to 0)

Number of stop bits

1 (default), 2

Flow control

XON/XOFF supported for the RS422 mode

Wait time

0 to 65535 ms

Table A- 70

Power supply

Technical data

CM 1241 RS422/485

Power loss (dissipation)

1.1 W

From +5 VDC

220 mA

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A.9 Communication interfaces
Table A- 71
Pin

RS485 or RS422 connector (female)
Description

Connector
(female)

Description

Logic or communication ground

6 PWR

+5 V with 100 ohm series resistor: Output

2 TxD+ 1

Connected for RS422
Not used for RS485: Output

Not connected

3 TxD+

Signal B (RxD/TxD+): Input/Output

8 TXD-

Signal A (RxD/TxD-): Input/Output

4 RTS 2

Request to send (TTL level) Output

9 TXD- 1

Connected for RS422
Not used for RS485: Output

5 GND

Logic or communication ground

SHELL

Chassis ground

Pins 2 and 9 are only used as transmit signals for RS422.

The RTS is a TTL level signal and can be used to control another half duplex device based on this signal. It is active
when you transmit and is inactive all other times.

A.9.4.3
Table A- 72

CM 1241 RS232 specifications
General specifications

Technical data

CM 1241 RS232

Order number

6ES7 241-1AH32-0XB0

Dimensions (mm)

30 x 100 x 75

Weight

150 grams

Table A- 73

Transmitter and receiver

Technical data

CM 1241 RS232

Type

RS232 (full-duplex)

Transmitter output voltage

+/- 5 V min. at RL = 3K Ω

Transmit output voltage

+/- 15 VDC max.

Receiver input impedance

3 K Ω min.

Receiver threshold/sensitivity

0.8 V min. low, 2.4 max. high
0.5 V typical hysteresis

Receiver input voltage

+/- 30 VDC max.

Isolation
RS 232 signal to chassis ground
RS 232 signal to CPU logic common

500 VAC, 1 minute

Cable length, shielded

10 m max.

Baud rate

300 baud, 600 baud, 1.2 kbits, 2.4 kbits, 4.8 kbits, 9.6 kbits (default),
19.2 kbits, 38.4 kbits, 57.6 kbits, 76.8 kbits, 115.2 kbits,

Parity

No parity (default), even, odd, Mark (parity bit always set to 1),
Space (parity bit always set to 0)

Number of stop bits

1 (default), 2

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A.10 Technology modules

Technical data

CM 1241 RS232

Flow control

Hardware, software

Wait time

0 to 65535 ms

Table A- 74

Power supply

Technical data

CM 1241 RS232

Power loss (dissipation)

From +5 VDC

200 mA

Table A- 75

RS232 connector (male)

Description

Connector
(male)

Description

1 DCD

Data carrier detect: Input

6 DSR

Data set ready: Input

2 RxD

Received data from DCE: Input

7 RTS

Request to send: Output

3 TxD

Transmitted data to DCE: Output

8 CTS

Clear to send: Input

4 DTR

Data terminal ready: Output

9 RI

Ring indicator (not used)

5 GND

Logic ground

SHELL

Chassis ground

A.10

Technology modules

A.10.1

SM 1278 4xIO-Link Master SM

A.10.1.1

SM 1278 4xIO-Link Master signal module specifications

Table A- 76

General specifications

Technical data

SM 1278 4xIO-Link Master signal module

Order number

6ES7 278-4BD32-0XB0

Dimensions W x H x D (mm)

45 x 100 x 75

Weight

150 grams

General information
I&M data

Yes; IM0 to IM3

Supply voltage
Rated voltage (DC)

24 VDC

Valid range low limit (DC)

19.2 V; 20.5 V if IO-Link is used (the supply voltage for
IO-Link devices on the master must be at least 20 V)

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Technical specifications
A.10 Technology modules

Technical data

SM 1278 4xIO-Link Master signal module

Valid range high limit (DC)

28.8 VDC

Polarity reversal protection

Yes

Input current
Current consumption

65 mA; without load

Encoder supply
Number of outputs

Output current, rated value

200 mA

Power loss
Power loss, typ.

1 W, excluding port loading

Digital inputs/outputs
Cable length (meters)

20 m, unshielded, max.

Cable length (meters)

20 m, unshielded, max.

SDLC
IO-Link
Number of ports

Number of ports which can be controlled at the same
time

IO-Link protocol 1.0

Yes

IO-Link protocol 1.1

Yes

Operating mode
IO-Link

Yes

Yes; max. 100 mA

Connection of IO-Link devices
Port type A
Transmission rate

Yes
4.8 kBd (COM1)
38.4 kBd (COM2)
230.4 kBd (COM3)

Cycle time, min.

2 ms, dynamic, dependent on the user data length

Size of process data, input per port

32 bytes; max.

Size of process data, input per module

32 bytes

Size of process data, output per port

32 bytes; max.

Size of process data, output per module

32 bytes

Memory size for device parameters

2 Kbytes

Cable length unshielded, max. (meters)

20 m

Interrupts/diagnostics/status information
Status display

Yes

Interrupts
Diagnostic interrupt

Yes; port diagnostics is only available in IO-Link mode

Diagnostic alarms
Diagnostics

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A.10 Technology modules

Technical data

SM 1278 4xIO-Link Master signal module

Monitoring of supply voltage

Yes

Short circuit

Yes

Diagostic indicator LED
Monitoring of supply voltage

Yes; flashing red DIAG LED

Channel status display

Yes; per channel one green LED for channel status Qn
(SIO mode) and PORT status Cn (IO-Link mode)

For channel diagnostics

Yes; red Fn LED

For module diagnostics

Yes; green/red DIAG LED

Electrical isolation
Electrical isolation channels
Between the channels

Between the channels and the backplane bus

Yes

Permitted potential difference
Between the different circuits

75 VDC / 60 VAC (basic insulation)

Insulation
Insulation tested with

707 VDC (type test)

Ambient conditions
Operating temperature
Min.

-20 °C

Max.

60 °C

Horizontal installation, min.

-20 °C

Horizontal installation, max.

60 °C

Vertical installation, min.

-20 °C

Vertical installation, max.

50 °C

Overview of the response time

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A.10 Technology modules

A.10.1.2
Table A- 77

SM 1278 4xIO-Link Master SM wiring diagrams
Wiring diagram for the SM 1278 IO-Link Master

SM 1278 IO-Link Master (6ES7 278-4BD32-0XB0)

Table A- 78

Connector pin locations for SM 1278 IO-Link Master (6ES7 278-4BD32-0XB0)

X10

X11

X12

X13

L+ / 24 VDC

No connection

M / 24 VDC

No connection

Functional Earth

No connection

C/Q1

C/QL2

C/Q3

C/QL4

ML1

ML2

ML4

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Technical specifications
A.11 Companion products

A.11

Companion products

A.11.1

PM 1207 power module
The PM 1207 is a power supply module for the SIMATIC S7-1200. It provides the following
features:
● Input 120/230 VAC, output 24 VDC/2.5A
● Order number 6ESP 332-1SH71-4AA0
For more information about this product and for the product documentation, refer to the
product catalog web site for the PM 1207.

See also
Customer support (http://www.siemens.com/automation/)

A.11.2

CSM 1277 compact switch module
The CSM1277 is an Industrial Ethernet compact switch module. It can be used to multiply
the Ethernet interface of the S7-1200 to allow simultaneous communication with operator
panels, programming devices, or other controllers. It provides the following features:
● 4 x RJ45 sockets for connecting to Industrial Ethernet
● 3 pole plug in terminal strip for connection of the external 24 VDC supply on top
● LEDs for diagnostics and status display of Industrial Ethernet ports
● Order number 6GK7 277-1AA00-0AA0
For more information about this product and for the product documentation, refer to the
product catalog web site for the CSM 1277.

See also
Customer support (http://www.siemens.com/automation/)

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Technical specifications
A.11 Companion products

A.11.3

CM CANopen module
The CM CANopen module is a plug-in module between the SIMATIC S7-1200 PLC and any
device running CANopen. The CM CANopen can be configured to be both master or slave.
There are two CM CANopen modules: the CANopen module (order number 021620-B), and
the CANopen (Ruggedized) module (order number 021730-B).
The CANopen module provides the following features:
● Able to connect 3 modules per CPU
● Connects up to 16 CANopen slave nodes
● 256 byte input and 256 byte output per module
● 3 LEDs provide diagnostic information on module, network, and I/O status
● Supports storage of CANopen network configuration in the PLC
● The module is integratable in the hardware catalogue of the TIA Portal configuration suite
● CANopen configuration via included CANopen Configuration Studio (included) or via any
other externanal CANopen configuration tool
● Complies to the CANopen communication profiles CiA 301 rev. 4.2 and the CiA 302 rev.
4.1
● Supports transparent CAN 2.0A for custom protocol handling
● Pre-made function blocks available for each PLC programming in TIA portal
● CM CANopen modules include; DSUB with screw terminals for subnetwork. CM
CANopen configuration studio CD, and USB configuration cable
For more information about this product and for the product documentation, refer to the
product catalog web site for the CM CANopen.

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Exchanging a V3.0 CPU for a V4.0 CPU
B.1

Exchanging a V3.0 CPU for a V4.0 CPU
You can replace your V3.0 CPU with a V4.0 CPU (Page 74) and use your existing STEP 7
project that you designed for the V3.0 CPU. You might also want to check for and apply
firmware updates (Page 269) to your connected modules.
Note
No device exchange possible from V4.0 to V3.0
You can exchange a V3.0 CPU for a V4.0 CPU, but you cannot exchange a V4.0 CPU for a
V3.0 CPU after you download the configuration. If you want to view or otherwise use your
existing STEP 7 V3.0 project, make an archive of your STEP 7 V3.0 project prior to the
device exchange.
Note that if you have not downloaded the exchanged device configuration, you can undo it.
After downloading, however, you cannot undo the exchange from V3.0 to V4.0.
You need to be aware of some configuration and operational changes between the two CPU
versions:

Organization blocks
With V4.0, you can configure OB execution to be interruptible or non-interruptible (Page 55).
For projects from former V3.0 CPUs, STEP 7 sets all OBs by default to be non-interruptible.
STEP 7 sets all OB priorities (Page 55) to the values they were in the V3.0 CPU STEP 7
project.
You can subsequently change the interruptability or priority settings if you choose.
The Diagnostic error interrupt OB start information references the submodule as a whole if
no diagnostics event is pending.

CPU password protection
STEP 7 sets the password protection level (Page 82) for the V4.0 CPU to be the equivalent
password protection level that was set for the V3.0 CPU, and assigns the V3.0 password to
the "Full access (no protection)" password for the V4.0 CPU:
V3.0 protection level

V4.0 access level

No protection

Full access (no protection)

Write protection

Read access

Write/read protection

HMI access

Note that the V4.0 access level "No access (complete protection)" did not exist for V3.0.

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Exchanging a V3.0 CPU for a V4.0 CPU
B.1 Exchanging a V3.0 CPU for a V4.0 CPU

Web server
If you exchange a V3.0 CPU for a V4.0 CPU, your Web server project settings for activating
the Web server and whether or not to require HTTPS access will be the same as they were
in V3.0. You can then configure users, privileges, passwords (Page 193), and languages as
needed to use the Web server. If you do not configure users with additional privileges, then
you are limited as to what you can view from the standard Web pages (Page 194). The S71200 V4.0 CPU does not support the former pre-configured "admin" user and password.
Formerly, the Data log Web server page provided a "Download and Clear" operation. The
V4.0 Web server File browser page (Page 194), from which you access data logs, no longer
provides this feature. Instead, the Web server provides the ability to download, rename, and
delete data log files.

Transfer card incompatibility
You cannot use a V3.0 transfer card (Page 58) to transfer a V3.0 program to a V4.0 CPU.
You must open the V3.0 project in STEP 7, change the device to a V4.0 CPU (Page 74), and
download the STEP 7 project to your V4.0 CPU. After you have changed your project to a
V4.0 project, you can then make a V4.0 transfer card for subsequent program transfers.

GET/PUT communication
By default, GET/PUT communication was enabled in V3.0. When you replace your V3.0
CPU with a V4.0 CPU (Page 74), you see a message in the compatibility information section
stating that GET/PUT is enabled.

Motion control support
S7-1200 V4.0 CPUs do not support the V1.0 and V2.0 motion libraries. If you perform a
device exchange for a STEP 7 project with V1.0 or V2.0 motion libraries, the device
exchange substitutes compatible V3.0 motion control instructions (Page 217) for the V1.0 or
V2.0 motion library instructions at compile.
If you perform a device exchange for a STEP 7 project that contains two different motion
control instruction versions (V3.0 and V4.0), the device exchange substitutes compatible
V4.0 motion control instructions (Page 217) at compile.
During a device exchange from V3.0 to V4.0, the motion control Technological Object (TO)
version automatically changes to V4.0. The TO structure is different between V3.0 and V4.0.
All associated blocks change as well. Block interfaces, watch tables, and traces update to
the new V4.0 structure. You can find the differences between the V3.0 and V4.0 motion
control axis parameters in the following two tables:
V3.0

V4.0

Config.General.LengthUnit

Units.LengthUnit

Config.Mechanics.PulsesPerDriveRevolution

Actor.DriveParameter.PulsesPerDriveRevolution

Config.Mechanics.LeadScrew

Mechanics.LeadScrew

Config.Mechanics.InverseDirection

Actor.InverseDirection

Config.DynamicLimits.MinVelocity

DynamicLimits.MinVelocity

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B.1 Exchanging a V3.0 CPU for a V4.0 CPU

V3.0

V4.0

Config.DynamicLimits.MaxVelocity

DynamicLimits.MaxVelocity

Config.DynamicDefaults.Acceleration

DynamicDefaults.Acceleration

Config.DynamicDefaults.Deceleration

DynamicDefaults.Deceleration

Config.DynamicDefaults.EmergencyDeceleration

DynamicDefaults.EmergencyDeceleration

Config.DynamicDefaults.Jerk

DynamicDefaults.Jerk

Config.PositionLimits_SW.Active

PositionLimitsSW.Active

Config.PositionLimits_SW.MinPosition

PositionLimitsSW.MinPosition

Config.PositionLimits_SW.MaxPosition

PositionLimitsSW.MaxPosition

Config.PositionLimits_HW.Active

PositionLimitsHW.Active

Config.PositionLimits_HW.MinSwitchedLevel

PositionLimitsHW.MinSwitchLevel

Config.PositionLimits_HW.MaxSwitchedLevel

PositionLimitsHW.MaxSwitchLevel

Config.Homing.AutoReversal

Homing.AutoReversal

Config.Homing.Direction

Homing.ApproachDirection

Config.Homing.SideActiveHoming

Sensor[1].ActiveHoming.SideInput

Config.Homing.SidePassiveHoming

Sensor[1].PassiveHoming.SideInput

Config.Homing.Offset

Sensor[1].ActiveHoming.HomePositionOffset

Config.Homing.FastVelocity

Homing.ApproachVelocity

Config.Homing.SlowVelocity

Homing.ReferencingVelocity

MotionStatus.Position

Position

MotionStatus.Velocity

Velocity

MotionStatus.Distance

StatusPositioning.Distance

MotionStatus.TargetPosition

StatusPositioning.TargetPosition

StatusBits.SpeedCommand

StatusBits.VelocityCommand

StatusBits.Homing

StatusBits.HomingCommand

The only "commandtable" parameter that is renamed is the array with the commands:
V3.0
Config.Command[]

V4.0
Command[]

Note: The array "Command[]" is a UDT of the type "TO_CmdTab_Config_Command" in V3.0 and
"TO_Struct_Command" in V4.0.

Instruction changes
The following instructions have changes in parameters or behavior:
● RDREC and WRREC (Page 132)
● CONV (Page 101)

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B.1 Exchanging a V3.0 CPU for a V4.0 CPU

HMI panel communication
If you had one or more HMI panels (Page 22) connected to your S7-1200 V3.0 CPU, the
communication to the S7-1200 V4.0 CPU depends on the type of communication you use
and the firmware version of the HMI panel. Recompile and download your project to the CPU
and the HMI and/or update your HMI firmware.

Requirement to recompile program blocks
After exchanging a V3.0 CPU for a V4.0 CPU, you must recompile all program blocks before
you can download them to the V4.0 CPU. Additionally, if any of the blocks have know-how
protection (Page 84) or copy protection bound to a PLC serial number (Page 85), you must
remove the protection before you compile and download the blocks. (You do not, however,
need to deactivate copy protection bound to a memory card.) After the download, you can
reconfigure the know-how protection and/or PLC serial number copy protection. Note that if
your project includes any blocks with know-how protection that an OEM (Original Equipment
Manufacturer) provided, you must contact the OEM to provide V4.0 versions of those blocks.
In general, Siemens recommends that you recompile the hardware configuration and
software in STEP 7 and download to all devices in your project after the device exchange.
Refer to the S7-1200 System Manual for complete details on the V4.0 features.

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