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User Manual: Chapter 8 Do-more H2 Series PLC Hardware User Manual - AutomationDirect

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Chapter 8 - Installation andWiring
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InstallatIon and

WIrIng 1

Chapter

In This Chapter...

Safety Guidelines .......................................................................................................8–2

Plan for Safety ..........................................................................................................8–2

Three Levels of Protection ........................................................................................8–3

Emergency Stops ......................................................................................................8–3

Emergency Power Disconnect ..................................................................................8–4

Orderly System Shutdown ........................................................................................8–4

Class 1, Division 2, Approval ....................................................................................8–4

Mounting Guidelines ................................................................................................. 8–5

Base Dimensions ......................................................................................................8–5

Panel Mounting and Layout .....................................................................................8–6

Enclosures ................................................................................................................8–7

Environmental Specifications ....................................................................................8–8

Marine Use ...............................................................................................................8–8

Agency Approvals ....................................................................................................8–8

24VDC Power Bases .................................................................................................8–8

Installing Bases for Do-more ..................................................................................... 8–9

Mounting the Base ...................................................................................................8–9

Using Mounting Rails ...............................................................................................8–9

Installing Components in the Base .........................................................................8–10

Base Wiring Guidelines ............................................................................................8–11

Base Wiring ............................................................................................................8–11

I/O Modules Position and Wiring ...........................................................................8–12

Slot Numbering......................................................................................................8–12

Module Placement Restrictions ...............................................................................8–12

Wiring the Different Module Connectors ................................................................8–13

I/O Wiring Checklist ...............................................................................................8–14

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–2

Table of Contents

ZIPLink Wiring System .............................................................................................8–15

I/O Wiring Strategies ..............................................................................................8–17

PLC Isolation Boundaries ........................................................................................8–17

Powering I/O Circuits with the Auxiliary Supply .....................................................8–18

Powering I/O Circuits Using Separate Supplies ....................................................... 8–19

Sinking / Sourcing Concepts ..................................................................................8–20

I/O “Common” Terminal Concepts ........................................................................8–21

Connecting DC I/O to “Solid State” Field Devices ..................................................8–22

Solid State Input Sensors ........................................................................................ 8–22

Solid State Output Loads ........................................................................................8–22

Relay Output Guidelines .........................................................................................8–24

Relay Outputs – Transient Suppression for Inductive Loads in a Control System .....8–25

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–3

Chapter 8: Installation and Wiring

Safety Guidelines

NOTE: Products with CE marks perform their required functions safely and adhere to relevant standards

as speciﬁed by CE directives, provided they are used according to their intended purpose and that the

instructions in this manual are followed. The protection provided by the equipment may be impaired if

this equipment is used in a manner not speciﬁed in this manual. A listing of our international afﬁliates is

available on our Web site: http://www.automationdirect.com

WARNING: Providing a safe operating environment for personnel and equipment is your responsibility

and should be your primary goal during system planning and installation. Automation systems

can fail and may result in situations that can cause serious injury to personnel and/or damage

equipment. Do not rely on the automation system alone to provide a safe operating environment.

Sufficient emergency circuits should be provided to stop either partially or totally the operation of

the PLC or the controlled machine or process. These circuits should be routed outside the PLC in

the event of controller failure, so that independent and rapid shutdown are available. Devices, such

as “mushroom” switches or end of travel limit switches, should operate motor starter, solenoids,

or other devices without being processed by the PLC. These emergency circuits should be designed

using simple logic with a minimum number of highly reliable electromechanical components.

Every automation application is different, so there may be special requirements for your particular

application. Make sure all national, state, and local government requirements are followed for the

proper installation and use of your equipment.

Plan for Safety

The best way to provide a safe operating environment is to make personnel and equipment

safety part of the planning process. You should examine every aspect of the system to determine

which areas are critical to operator or machine safety.

If you are not familiar with PLC system installation practices, or your company does not

have established installation guidelines, you should obtain additional information from the

following sources.

• NEMA — The National Electrical Manufacturers Association, located in Washington, D.C.,

publishes many different documents that discuss standards for industrial control systems.

You can order these publications directly from NEMA. Some of these include:

ICS 1, General Standards for Industrial Control and Systems

ICS 3, Industrial Systems

ICS 6, Enclosures for Industrial Control Systems

• NEC — The National Electrical Code provides regulations concerning the installation and

use of various types of electrical equipment. Copies of the NEC Handbook can often be

obtained from your local electrical equipment distributor or your local library.

• Local and State Agencies — many local governments and state governments have additional

requirements above and beyond those described in the NEC Handbook. Check with your

local Electrical Inspector or Fire Marshall ofﬁce for information.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–4

Chapter 8: Installation and Wiring

Three Levels of Protection

The publications mentioned provide many ideas and requirements for system safety. At a

minimum, you should follow these regulations. Also, you should use the following techniques,

which provide three levels of system control.

• Emergency stop switch for disconnecting system power

• Mechanical disconnect for output module power

• Orderly system shutdown sequence in the PLC control program

Emergency Stops

It is recommended that emergency stop circuits be incorporated into the system for every

machine controlled by a PLC. For maximum safety in a PLC system, these circuits must not

be wired into the controller, but should be hardwired external to the PLC. The emergency

stop switches should be easily accessed by the operator and are generally wired into a master

control relay (MCR) or a safety control relay (SCR) that will remove power from the PLC I/O

system in an emergency.

MCRs and SCRs provide a convenient means for removing power from the I/O system

during an emergency situation. By de-energizing an MCR (or SCR) coil, power to the input

(optional) and output devices is removed. This event occurs when any emergency stop switch

opens. However, the PLC continues to receive power and operate even though all its inputs

and outputs are disabled.

The MCR circuit could be extended by placing a PLC fault relay (closed during normal

PLC operation) in series with any other emergency stop conditions. This would cause

the MCR circuit to drop the PLC I/O power in case of a PLC failure (memory error, I/O

communications error, etc.).

Output

Module Saw

Arbor

E STOP Master

Relay

Emergency

Stop

Power On

Master Relay Contacts

To disconnect output

module power

Use E-Stop and Master Relay

Guard

Limit

Guard Limit Switch

Master

Relay

Contacts

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–5

Chapter 8: Installation and Wiring

Emergency Power Disconnect

A properly rated emergency power disconnect should be used to power the PLC controlled

system as a means of removing the power from the entire control system. After an emergency

shutdown or any other type of power interruption, there may be requirements that must be

met before the PLC control program can be restarted. For example, there may be speciﬁc

before operations can resume. In this case, you may want to use retentive memory locations, or

include constants in the control program to insure a known starting point.

Orderly System Shutdown

Ideally, the ﬁrst level of fault detection is the PLC control

program, which can identify machine problems. Certain

shutdown sequences should be performed. The types of

problems are usually things such as jammed parts, etc. that

do not pose a risk of personal injury or equipment damage.

WARNING: The control program must not be the only form of

protection for any problems that may result in a risk of personal

injury or equipment damage.

Class 1, Division 2, Approval

This equipment is suitable for use in Class 1, Division 2, Zone 2, groups A, B, C and D or

non-hazardous locations only.

WARNING: Explosion Hazard! Substitution of components may impair suitability for Class 1, Division 2,

Zone 2.

WARNING: Explosion Hazard - Do not disconnect equipment unless power has been switched off or the

area is known to be non-hazardous.

WARNING: All Do-more products used with connector accessories must use R/C (ECBT2) mating plugs.

All mating plugs must have suitable ratings for the devices.

Turn off

Saw

Jam

Detect

RST

Retract

Arm

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–6

Chapter 8: Installation and Wiring

Mounting Guidelines

Before installing the PLC system you will need to know the dimensions of the components

considered. The diagrams on the following pages provide the component dimensions to use

in deﬁning your enclosure speciﬁcations. Remember to leave room for potential expansion.

NOTE: If you are using other components in your system, refer to the appropriate manual to determine

how those units can affect mounting dimensions.

Base Dimensions

The following information shows the proper mounting dimensions. The height dimension is

the same for all bases. The depth varies depending on your choice of I/O module. The length

varies as the number of slots increase. Make sure you have followed the installation guidelines

for proper spacing.

Base

(Base Total Width)

(Mounting Hole)

(Component Width)

Inches Millimeters Inches Millimeters Inches Millimeters

3-slot 6.77 172 6.41 163 5.8 148

4-slot 7.99 203 7.63 194 7.04 179

6-slot 10.43 265 10.07 256 9.48 241

9-slot 14.09 358 13.74 349 13.14 334

7.91"

(201mm)

ZL-D24-CBL40

ZipLink cable

5.85”

(148mm)

3.62”

(92mm)

D2-DSCBL-1

Approximate

Dimension

12 or 16pt. I/O

3.62”

(92mm)

2.95”

(75mm)

4 or 8pt. I/O

4.76"

(121mm)

ZL-D24-CBL40-X

ZipLink cable

3.54”

(90mm)

2.99”

(76mm)

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

H2-DM1E

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–7

Chapter 8: Installation and Wiring

Panel Mounting and Layout

It is important to design your panel properly to help ensure the components operate within their

environmental and electrical limits. The system installation should comply with all appropriate

electrical codes and standards. It is important the system also conforms to the operating standards

for the application to insure proper performance. The diagrams below reference the items in the

following list.

1. Mount the bases horizontally to provide proper ventilation.

2. If you place more than one base in a cabinet, there should be a minimum of 7.2 in. (183mm) between

bases.

3. Provide a minimum clearance of 2in. (50mm) between the base and all sides of the cabinet. There

should also be at least 1.2 in. (30mm) of clearance between the base and any wiring ducts.

4. There must be a minimum of 2in. (50mm) clearance between the panel door and the nearest

component.

NOTE: The cabinet conﬁguration below is not suitable for EU installations. Refer to Appendix B European Union

Directives.

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

50.8mm

minimum

1.2"

30mm

minimum

50.8mm

minimum

inim

Airflow

Ai fl

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

H2-DM1E

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–8

Chapter 8: Installation and Wiring

5. The ground terminal on the Do-more base must be connected to a single point ground. Use

copper stranded wire to achieve a low impedance. Copper eye lugs should be crimped and

soldered to the ends of the stranded wire to ensure good surface contact. Remove anodized

ﬁnishes and use copper lugs and star washers at termination points. A general rule is to achieve a

0.1 ohm of DC resistance between the base and the single point ground.

6. There must be a single point ground (i.e. copper bus bar) for all devices in the panel requiring

an earth ground return. The single point of ground must be connected to the panel ground

termination. The panel ground termination must be connected to earth ground. For this

connection you should use #12 AWG stranded copper wire as a minimum. Minimum wire sizes,

color coding, and general safety practices should comply with appropriate electrical codes and

standards for your region. A good common ground reference (Earth ground) is essential for proper

operation of the Do-more. There are several methods of providing an adequate common ground

reference, including:

a) Installing a ground rod as close to the panel as possible.

b) Connection to incoming power system ground.

7. Properly evaluate any installations where the ambient temperature may approach the lower or

upper limits of the speciﬁcations. Place a temperature probe in the panel, close the door and

operate the system until the ambient temperature has stabilized. If the ambient temperature is not

within the operating speciﬁcation for the Do-more system, measures such as installing a cooling/

heating source must be taken to get the ambient temperature within the operating speciﬁcations.

8. Device mounting bolts and ground braid termination bolts should be #10 copper bolts or

equivalent. Tapped holes instead of nut–bolt arrangements should be used whenever possible. To

ensure good contact on termination areas impediments such as paint, coating or corrosion should

be removed in the area of contact.

9. The Do-more system is designed to be powered by 110/220 VAC, 24 VDC, or 125 VDC

normally available throughout an industrial environment. Electrical power in some areas where

the PLCs are installed is not always stable and storms can cause power surges. Due to this,

powerline ﬁlters are recommended for protecting the PLCs from power surges.

Enclosures

Your selection of a proper enclosure is important to ensure safe and proper operation of your

Do-more system. Applications of Do-more systems vary and may require additional features.

The minimum considerations for enclosures include:

• Conformance to electrical standards

• Protection from the elements in an industrial environment

• Common ground reference

• Maintenance of speciﬁed ambient temperature

• Access to equipment

• Security or restricted access

• Sufﬁcient space for proper installation and maintenance of equipment

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–9

Chapter 8: Installation and Wiring

Environmental Speciﬁcations

The following table lists the environmental speciﬁcations that generally apply to the Do-more system

(CPU, Bases, I/O Modules). I/O module operation may ﬂuctuate depending on the ambient

temperature and your application. Please refer to the appropriate I/O module speciﬁcations for

the temperature derating curves applying to speciﬁc modules.

Marine Use

American Bureau of Shipping (ABS) certiﬁcation requires ﬂame-retarding insulation as per 4-8-

3/5.3.6(a). ABS will accept Navy low smoke cables, cable qualiﬁed to NEC “Plenum rated” (ﬁre

resistant level 4), or other similar ﬂammability resistant rated cables. Use cable speciﬁcations

for your system that meet a recognized ﬂame retardant standard (i.e. UL, IEEE, etc.) including

evidence of cable test certiﬁcation (i.e. tests certiﬁcate, UL ﬁle number, etc.).

NOTE: Wiring needs to be “low smoke” per the above paragraph. Teﬂon coated wire is also recommended.

Agency Approvals

Some applications require agency approvals. Typical agency approvals which your application

may require are:

• UL (Underwriters’ Laboratories, Inc.)

• CSA (Canadian Standards Association)

• FM (Factory Mutual Research Corporation)

• cUL (Canadian Underwriters’ Laboratories, Inc.)

24VDC Power Bases

Follow these additional installation guidelines when installing D2-03BDC1-1, D2-04BDC1-1,

D2-06BDC1-1 and D2-09BDC1-1 bases:

• Install these bases in compliance with the enclosure, mounting, spacing, and segregation requirements

of the ultimate application.

• These bases must be used within their marked ratings.

• These bases are intended to be installed within an enclosure rated at least IP54.

• Provisions should be made to prevent the rated voltage being exceeded by transient disturbances of

more than 40%.

Specification Rating

Storage temperature –4° F to 158° F (–20° C to 70° C)

Ambient operating temperature 32° F to 131° F (0° C to 55° C)

Ambient humidity* 30% – 95% relative humidity (Non–condensing)

Vibration resistance MIL STD 810C, Method 514.2

Shock resistance MIL STD 810C, Method 516.2

Noise immunity NEMA (ICS3–304)

Atmosphere No corrosive gases

* Equipment will operate below 30% humidity. However, static electricity problems occur much more

frequently at lower humidity levels. Make sure you take adequate precautions when you touch the

equipment. Consider using ground straps, anti-static ﬂoor coverings, etc., if you use the equipment in

low humidity environments.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–10

Chapter 8: Installation and Wiring

Installing Bases for Do-more

Mounting the Base

All I/O configurations of the

Do-more may use any of the base

conﬁgurations. The bases are secured

to the equipment panel or mounting

location using four M4 screws in

the corner tabs of the base. The full

mounting dimensions are given in

the previous section on Mounting

Guidelines.

WARNING: To minimize the risk of electrical shock, personal injury, or equipment damage, always

disconnect the system power before installing or removing any system component.

Using Mounting Rails

The bases can also be secured to the cabinet by using mounting rails. You should use rails that

conform to DIN EN standard 50 022. Refer to our catalog for a complete line of DIN rail,

DINnectors and DIN rail mounted apparatus.

These rails are approximately 35mm high, with a depth of 7.5 mm. If you mount the base on a

rail, you should also consider using end brackets on each end of the rail. The end brackets help

keep the base from sliding horizontally along

the rail. This helps minimize the possibility of

accidentally pulling the wiring loose.

If you examine the bottom of the base, you’ll

notice small retaining clips. To secure the

base to a DIN rail, place the base onto the

rail and gently push up on the retaining

clips. The clips lock the base onto the rail.

To remove the base, pull down on the

retaining clips, lift up on the base slightly,

and pull it away from the rail.

DIN Rail (Part No. DN-R35S1)

End Bracket (Part No. DN-EB35)

DIN Rail

Dimensions

7.5 mm

35 mm

Rotate base

into position.

Hook base

onto DIN rail at

top of mount-

ing slot.

Gently push up

retaining clips.

Retaining Clips

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

H2-DM1E

S-

TER

H2-DM1E

Mounting Clips

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–11

Chapter 8: Installation and Wiring

Installing Components in the Base

To insert components into the base: ﬁrst slide the module retaining clips to the out position

and align the PC board(s) of the module with the grooves on the top and bottom of the base.

Push the module straight into the base until it is ﬁrmly seated in the backplane connector.

Once the module is inserted into the base, push in the retaining clips to ﬁrmly secure the

module to the base.

WARNING: To minimize the risk of electrical shock, personal injury, or equipment damage, always

disconnect the system power before installing or removing any system component.

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

S-

TERM

H2-DM1E

CPU must be positioned in the

ﬁrst slot of the base

Align module PC board to slots

in base and slide in

Push the retaining clips

in to secure the module to

the Do-more base

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–12

Chapter 8: Installation and Wiring

Base Wiring Guidelines

Base Wiring

The following diagrams show the terminal

connections located on the power supply of the

Do-more bases. The base terminals can accept up

to 16 AWG. You may be able to use larger wiring

depending on the type of wire used, but 16 AWG

is the recommended size. Do not overtighten

the connector screws; the recommended torque

value is 7.81 lb·in (0.882 N·m).

NOTE: You can connect either a 115VAC or 220VAC supply to the AC terminals without the need of special

wiring or jumpers.

WARNING: Once the power wiring is connected, install the plastic protective cover. When the cover is

removed there is a risk of electrical shock if you accidentally touch the wiring or wiring terminals.

125 VDC Base T erminal Strip 12/24 VDC Base T erminal Strip

10.2 – 28.8 VDC

–

1 20 – 240 VDC

24 VDC OUT, 0.3A

–

1 10/220 V AC Base T erminal Strip

100 – 240 VAC

24 VDC OUT, 0.3A

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–13

Chapter 8: Installation and Wiring

I/O Modules Position and Wiring

Slot Numbering

The bases provide different numbers of slots for use with the I/O modules. You may notice

the bases refer to 3-slot, 4-slot, etc. One of the slots is dedicated to the CPU, so you always

have one less I/O slot. For example, you have ﬁve I/O slots with a 6-slot base. The I/O slots

are numbered 0–4. The CPU slot always contains a PLC CPU or other CPU–slot controller

and is not numbered.

Module Placement Restrictions

The following table lists the valid locations for all types of modules in a Do-more system:

Module/Unit Local CPU Base Ethernet Remote I/O Base

CPUs CPU Slot Only

DC Input Modules x x

AC Input Modules x x

DC Output Modules x x

AC Output Modules x x

Relay Output Modules x x

Analog Input and Output Modules x x

Ethernet Remote I/O

Ethernet Remote Master x

CPU Interface

Ethernet Base Controller CPU Slot Only

Specialty Modules

Counter I/O x

Ethernet Communications x

Simulator x x

Filler x x

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

H2-DM1E

H2 DM1E

RUN

TERM

STO

USB

PGM

PORT

RUN

STO

PORT

-2

ERIA

CPU Slot I/O Slots

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–14

Chapter 8: Installation and Wiring

Wiring the Different Module Connectors

There are two types of module connectors for the Do-more I/O. Some modules have normal

screw terminal connectors. Other modules have connectors with recessed screws. The recessed

screws help minimize the risk of someone accidentally touching active wiring.

Both types of connectors can be easily removed. If you examine the connectors closely, you’ll

notice there are squeeze tabs on the top and bottom. To remove the terminal block, press the

squeeze tabs and pull the terminal block away from the module.

We also have DIN rail mounted terminal blocks, DINnectors (refer to our catalog for a complete

listing of all available products). ZIPLink systems come with special pre–assembled cables with

the I/O connectors installed and wired.

WARNING: For some modules, field device power may still be present on the terminal block even though

the PLC system is turned off. To minimize the risk of electrical shock, check all field device power before

you remove the connector.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–15

Chapter 8: Installation and Wiring

I/O Wiring Checklist

Use the following guidelines when wiring the I/O modules in your system.

1. There is a limit to the size of wire the modules can accept. The table below lists the suggested

AWG for each module type. When making terminal connections, follow the suggested torque

values.

NOTE: 16 AWG Type TFFN or Type MTW is recommended. Other types of 16 AWG may be acceptable, but

it really depends on the thickness and stiffness of the wire insulation. If the insulation is too thick or stiff

and a majority of the module’s I/O points are used, then the plastic terminal cover may not close properly

or the connector may pull away from the module. This applies especially for high temperature

thermoplastics such as THHN.

2. Always use a continuous length of wire, do not combine wires to attain a needed length.

3. Use the shortest possible wire length.

4. Use wire trays for routing where possible.

5. Avoid running wires near high energy wiring. Also, avoid running input wiring close to output

wiring where possible.

6. To minimize voltage drops when wires must run a long distance , consider using multiple wires for

the return line.

7. Avoid running DC wiring in close proximity to AC wiring where possible.

8. Avoid creating sharp bends in the wires.

9. To reduce the risk of having a module with a blown fuse,

we suggest you add external fuses to your I/O wiring. A fast

blow fuse, with a lower current rating than the I/O module

fuse can be added to each common, or a fuse with a rating

of slightly less than the maximum current per output point

can be added to each output. Refer to our catalog for a

complete line of DINnectors, DIN rail mounted fuse

blocks.

Module type Suggested AWG Range Suggested Torque

4 point 16–24 AWG 7.81 lb·in (0.882 N·m)

8 point 16–24 AWG 7.81 lb·in (0.882 N·m)

12 point 16–24 AWG 2.65 lb·in (0.3 N·m)

16 point 16–24 AWG 2.65 lb·in (0.3 N·m)

H2-DM1E

DINnector External Fuses

(DIN rail mounted Fuses)

RS-232

SERIAL

USB

PGM

PORT

RUN

TERM

STOP

S-

TERM

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–16

Chapter 8: Installation and Wiring

ZIPLink Wiring System

The ZIPLink I/O connector systems allows quick and

easy connections using cables that are prewired to the I/O

module terminal blocks at one end and plug into a ZIPLink

connector module terminal block at the other end.

Use the following tables to specify your ZIPLink wiring system.

See the ZIPLink section of the catalog for more details.

ZIPLink system

connected to an I/O

Module

Do-more PLC Input Module ZIPLink Selector

PLC ZIPLink

Input

Module

# of

Terms Component Module Cable †

D2-08ND3 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-16ND3-2 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Sensor ZL-LTB16-24 ZL-D2-CBL19*

D2-32ND3¹ 40

Feedthrough ZL-RTB40 ZL-D24-CBL40*

ZL-D24-CBL40*X

Sensor ZL-LTB32-24 ZL-D24-CBL40*

ZL-D24-CBL40*X

D2-32ND3-2¹40

Feedthrough ZL-RTB40 ZL-D24-CBL40*

ZL-D24-CBL40*X

Sensor ZL-LTB32-24 ZL-D24-CBL40*

ZL-D24-CBL40*X

D2-08NA-1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-08NA-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-16NA 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Do-more PLC Analog Module ZIPLink Selector

PLC ZIPLink

Analog

Module

# of

Terms Component Module Cable

F2-04AD-1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08AD-1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-04AD-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08AD-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-02DA-1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-02DA-1L 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-02DAS-1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08DA-1 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

F2-02DA-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-02DA-2L 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-02DAS-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08DA-2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-4AD2DA 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-8AD4DA-1 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

F2-8AD4DA-2 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

F2-04RTD2Matched

Only See Note 2

F2-04THM2Matched

Only See Note 2

† X in the part number represents a 45° angle plug

* Select the cable length by replacing the * with: Blank = 0.5 m,

1 = 1.0 m, or -2 = 2.0 m.

1 To make a custom cable for the 32-point modules, use: Ribbon-style

Connector ZL-D24-CON-R, Solder-style 180° connector ZL-D24-CON

or Solder-style 45° connector ZL-D24-CON-X

2 The F2-04RTD and F2-04THM modules are not supported by the

ZIPLink wiring system.

Do-more PLC Combo In/Out Module ZIPLink

Selector

PLC ZIPLink

Combo

Module

# of

Terms Component Module Cable

D2-08CDR 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

NOTE: ZIPLink Connector Modules and ZIPLink Cables speciﬁcations

are in the ZIPLink catalog section.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–17

Chapter 8: Installation and Wiring

Do-more PLC Output Module ZIPLink Selector

PLC ZIPLink

Output Module # of Terms Component Module Cable †

D2-04TD1²10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-08TD1 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-08TD2 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-16TD1-2 19

Feedthrough ZL-RTB20 ZL-D2-CBL19*

Fuse ZL-RFU204ZL-D2-CBL19*

Relay ZL-RRL16-24-1 ZL-D2-CBL19*

D2-16TD2-2 19

Feedthrough ZL-RTB20 ZL-D2-CBL19*

Fuse ZL-RFU204ZL-D2-CBL19*

Relay ZL-RRL16-24-2 ZL-D2-CBL19*

F2-16TD1P 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Relay ZL-RRL16-24-1 ZL-D2-CBL19*

F2-16TD2P 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Relay ZL-RRL16-24-2 ZL-D2-CBL19*

D2-32TD1¹40

Feedthrough ZL-RTB40 ZL-D24-CBL40*

ZL-D24-CBL40*X

Fuse ZL-RFU404ZL-D24-CBL40*

ZL-D24-CBL40*X

D2-32TD2¹40

Feedthrough ZL-RTB40 ZL-D24-CBL40*

ZL-D24-CBL40*X

Fuse ZL-RFU404ZL-D24-CBL40*

ZL-D24-CBL40*X

D2-08TA 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08TA 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-12TA 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Fuse ZL-RFU204ZL-D2-CBL19*

D2-04TRS²10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-08TR 10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

F2-08TRS²19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

F2-08TR³10 Feedthrough ZL-RTB20 ZL-D2-CBL10*

D2-12TR 19 Feedthrough ZL-RTB20 ZL-D2-CBL19*

Fuse ZL-RFU204ZL-D2-CBL19*

† X in the part number represents a 45° angle plug

* Select the cable length by replacing the * with: Blank = 0.5 m, -1 = 1.0 m, or -2 = 2.0 m.

1 To make a custom cable for the 32-point modules, use: Ribbon-style Connector ZL-D24-CON-R,

Solder-style 180° connector ZL-D24-CON or Solder-style 45° connector ZL-D24-CON-X

2 Caution: The D2-04TD1, D2-04TRS, and F2-08TRS outputs are derated not to exceed module specs

2A per point and 2A per common when used with the ZIPLink wiring system.

3 The F2-08TR outputs are derated not to exceed 2A per point and 4A per common when used with

the ZIPLink wiring system.

4 Note: Fuses (5 x 20 mm) are not included. See Edison Electronic Fuse section for (5 x 20 mm) fuse.

S500 and GMA electronic circuit protection for fast-acting maximum protection. S506 and GMC

electronic circuit protection for time-delay performance. Ideal for inductive circuits. To ensure

proper operation, do not exceed the voltage and current rating of ZIPLink module. ZL-RFU20 = 2A

per circuit; ZL-RFU40 = 400mA per circuit.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–18

Chapter 8: Installation and Wiring

I/O Wiring Strategies

The Do-more PLC system is very ﬂexible and will work in many different wiring conﬁgurations.

By studying this section before actual installation, you can probably ﬁnd the best wiring

strategy for your application. This will help to lower system cost, wiring errors, and avoid

safety problems.

PLC Isolation Boundaries

PLC circuitry is divided into three main regions separated by isolation boundaries, shown in

the drawing below. Electrical isolation provides safety, so that a fault in one area does not

damage another. A transformer in the power supply provides isolation between the primary

and secondary sides. Opto-couplers provide isolation in Input and Output circuits. This

isolates logic circuitry from the ﬁeld side, where factory machinery connects. Note the discrete

inputs are isolated from the discrete outputs, because each is isolated from the logic side.

Isolation boundaries protect the operator interface (and the operator) from power input faults

or ﬁeld wiring faults. When wiring a PLC, it is extremely important to avoid making external

connections that connect logic side circuits to any other.

In addition to the basic circuits covered above, AC-powered and 125VDC bases include an

auxiliary +24VDC power supply with its own isolation boundary. Since the supply output is

isolated from the other three circuits, it can power input and/or output circuits!

Safety Guidelines

Input Module

CPU

Comm.

Main

Power

Supply

Auxiliary

+24VDC

Supply

T o Programming

Device, Operator

Inputs Commons Commons Outputs

+24VDC Out

PLC

Interface, Network

Output Module

Internal Backplane

Supply for

Output Circuit

Primary Side Secondary , or

Logic side

Field Side

Power

Input

CPU

Input

Module

Main

Power

Supply

Inputs

Outputs

Power

Input

Output

Module

Primary Side Secondary, or

Logic side

Field Side

PLC

Programming Device,

Operator Interface, or Network

Isolation

Boundary

Isolation

Boundary

(backplane)

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–19

Chapter 8: Installation and Wiring

Powering I/O Circuits with the Auxiliary Supply

In some cases, using the built-in auxiliary +24VDC supply can result in a cost savings for your

control system. It can power combined loads up to 300mA. Be careful not to exceed the current

rating of the supply. If you are the system designer for your application, you may be able to

select and design in ﬁeld devices which can use the +24VDC auxiliary supply.

All AC powered and 125VDC bases feature the internal auxiliary supply. If input devices AND

output loads need +24VDC power, the auxiliary supply may be able to power both circuits as

shown in the following diagram.

The 12/24VDC powered bases are designed for application environments in which low-

voltage DC power is more readily available than AC. These include a wide range of

battery–powered applications, such as remotely-located control, in vehicles, portable machines,

etc. For this application type, all input devices and output loads typically use the same DC

power source. Typical wiring for DC-powered applications is shown in the following diagram.

Input Module

Auxiliary

+24VDC

Supply

Power Input Do-more PLC

Output Module

Loads

AC Power or 125VDC Bases

+ –

Inputs Com. Outputs Com.

Input Module

Power Input

PLC

Output Module

Loads

DC Power

–

Inputs Com. Outputs Com.

Do-more

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–20

Chapter 8: Installation and Wiring

Powering I/O Circuits Using Separate Supplies

In most applications it will be necessary to power the input devices from one power source,

and to power output loads from another source. Loads often require high-energy AC power,

while input sensors use low-energy DC. If a machine operator is likely to come in close

contact with input wiring, then safety reasons also require isolation from high-energy output

circuits. It is most convenient if the loads can use the same power source as the PLC, and the

input sensors can use the auxiliary supply, as shown to the left in the ﬁgure below.

If the loads cannot be powered from the PLC supply, then a separate supply must be used as

shown to the right in the ﬁgure below.

Some applications will use the PLC external power source to also power the input circuit.

This typically occurs on DC-powered PLCs, as shown in the drawing below to the left. The

inputs share the PLC power source supply, while the outputs have their own separate supply.

A worst-case scenario, from a cost and complexity viewpoint, is an application which requires

separate power sources for the PLC, input devices, and output loads. The example wiring

diagram below on the right shows how this can work, but also the auxiliary supply output is

an unused resource. You will want to avoid this situation if possible.

Input Module

Auxiliary

+24VDC

Supply

Power Input PLC

Output Module

Loads

AC Power

+ –

Inputs Com. Outputs Com.

Input Module

Auxiliary

+24VDC

Supply

Power Input PLC

Output Module

Loads

AC Power

+ –

Inputs Com. Outputs Com.

Load

Supply

Do-more Do-more

Input Module

Power Input

PLC

Output Module

Loads

DC Power

–

Inputs Com. Outputs Com.

Load

Supply

Input Module

Auxiliary

+24VDC

Supply

Power Input PLC

Output Module

Loads

AC Power

+ –

Inputs Com. Outputs Com.

Load

Supply

Input

Supply

Do-more Do-more

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–21

Chapter 8: Installation and Wiring

Sinking / Sourcing Concepts

Before going further in the study of wiring strategies, you must have a solid understanding of

“sinking” and “sourcing” concepts. Use of these terms occurs frequently in input or output

circuit discussions. It is the goal of this section to make these concepts easy to understand,

further ensuring your success in installation. First the following short deﬁnitions are provided,

followed by practical applications.

Sinking = provides a path to supply ground (–)

Sourcing = provides a path to supply source (+)

First you will notice these are only associated with DC circuits and not AC, because of the

reference to (+) and (–) polarities. Therefore, sinking and sourcing terminology only applies

to DC input and output circuits. Input and output points that are sinking only or sourcing

only can conduct current in only one direction. This means it is possible to connect the

external supply and ﬁeld device to the I/O point with current trying to ﬂow in the wrong

direction, and the circuit will not operate. However, you can successfully connect the supply

and ﬁeld device every time by understanding “sourcing” and “sinking”.

For example, the ﬁgure to the right depicts a “sinking”

input. To properly connect the external supply, you

will have to connect it so the input provides a path to

ground (–). Start at the PLC input terminal, follow

through the input sensing circuit, exit at the common

terminal, and connect the supply (–) to the common

terminal. By adding the switch, between the supply

(+) and the input, the circuit has been completed .

Current ﬂows in the direction of the arrow when the

switch is closed.

Apply the circuit principle above to the four possible

combinations of input/output sinking/sourcing types as shown below. The I/O module

speciﬁcations found in the “Speciﬁcations” chapters list the input or output type.

–

Input

Sensing

PLC

Input

Common

(sinking)

–

Input

Sensing

Load

Sinking Input Sinking Output

Sourcing Input Sourcing Output

PLC

Input

Common

–

Output

Switch

PLC Output

Common

–

Input

Sensing

Load

PLC

Input

Common

–

Output

Switch

PLC

Output

Common

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–22

Chapter 8: Installation and Wiring

I/O “Common” Terminal Concepts

In order for a PLC I/O circuit to operate,

current must enter at one terminal and exit at

another. Therefore, at least two terminals are

associated with every I/O point. In the ﬁgure

to the right, the Input or Output terminal is

the main path for the current. An additional

terminal must provide the return path to the

power supply.

If there were unlimited space and budget for

I/O terminals, every I/O point could have

two dedicated terminals as the ﬁgure above

shows. However, providing this level of

ﬂexibility is not practical or even necessary for

most applications. So, most Input or Output

points on PLCs are in groups which share the

return path (called commons). The ﬁgure

to the right shows a group (or bank) of four

input points which share a common return

path. In this way, the four inputs require only

ﬁve terminals instead of eight.

NOTE: In the circuit above, the current in the common path is 4 times any channel’s input current when

all inputs are energized. This is especially important in output circuits, where heavier gauge wire is

sometimes necessary on commons.

Most Do-more input and output modules group their I/O

points into banks that share a common return path. The best

indication of I/O common grouping is on the wiring label, such

as the one shown to the right. There are two circuit banks with

eight input points in each. The common terminal for each is

labeled “CA” and “CB”, respectively.

In the wiring label example, the positive terminal of a DC supply

connects to the common terminals. Some symbols you will see

on the wiring labels, and their meanings are:

AC supply AC or DC supply

Input Switch Output Load

DC supply

+–

–

I/O

Circuit

PLC

(I/O Point)

Return Path

Field

Device

Main Path

–

Input

Sensing

PLC

Input 4

Common

Input 3

Input 2

Input 1

D2-16ND3-2

VDC

20-28VDC

8mA

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–23

Chapter 8: Installation and Wiring

Connecting DC I/O to “Solid State” Field Devices

In the previous section on Sourcing and Sinking concepts, the DC I/O circuits were explained

to sometimes only allow current to ﬂow one way. This is also true for many of the ﬁeld devices

which have solid-state (transistor) interfaces. In other words, ﬁeld devices can also be sourcing

or sinking.

NOTE: When connecting two devices in a series DC circuit, one device must be wired as sourcing and the

other as sinking.

Solid State Input Sensors

Several DC input modules are ﬂexible because they detect current ﬂow in either direction,

so they can be wired as either sourcing or sinking. In the following circuit, a ﬁeld device has

an open-collector NPN transistor output. It sinks current from the PLC input point, which

sources current. The power supply can be the +24 auxiliary supply or another supply (+12

VDC or +24VDC), as long as the input speciﬁcations are met.

In the above circuit, a ﬁeld device has an open-collector PNP transistor output. It sources

current to the PLC input point, which sinks the current back to ground. Since the ﬁeld device

is sourcing current, no additional power supply is required.

Solid State Output Loads

Sometimes an application requires connecting a PLC output point to a solid state input on a

device. This type of connection is usually made to carry a low-level control signal, not to send

DC power to an actuator.

Several of the Do-more DC output modules are the sinking type. This means that each DC

output provides a path to ground when it is energized. In the following circuit, the PLC output

point sinks current to the output common when energized. It is connected to a sourcing input

of a ﬁeld device input.

Field Device

+–

PLC DC Input

Output

Ground

Input

Common

Supply

(sinking) (sourcing)

Field Device

PLC DC Input

Output (sourcing)

Ground

Input

Common

(sinking)

Field Device

Output

Ground

Input

Common

PLC DC Sinking Output

+DC pwr

–

(sourcing)

(sinking)

Power

10–30 VDC

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–24

Chapter 8: Installation and Wiring

In the next example a PLC sinking DC output point is connected to the sinking input of a ﬁeld

device. This is a little tricky, because both the PLC output and ﬁeld device input are sinking

type. Since the circuit must have one sourcing and one sinking device, a sourcing capability

needs to be added to the PLC output by using a pull-up resistor. In the circuit below, a Rpull-up

is connected from the output to the DC output circuit power input.

NOTE : DO NOT attempt to drive a heavy load (>25mA) with this pull-up method

NOTE : Using the pull-up resistor to implement a sourcing output has the effect of inverting the output

point logic. In other words, the ﬁeld device input is energized when the PLC output is OFF, from a ladder

logic point of view. Your ladder program must comprehend this and generate an inverted output. Or, you

may choose to cancel the effect of the inversion elsewhere, such as in the ﬁeld device.

It is important to choose the correct value of Rpull-up. In order to do so, you need to know the

nominal input current to the ﬁeld device (Iinput) when the input is energized. If this value is

not known, it can be calculated as shown (a typical value is 15mA). Then use Iinput and the

voltage of the external supply to compute Rpull-up. Then calculate the power Ppull-up (in watts),

in order to size Rpull-up properly.

Of course, the easiest way to drive a sinking input ﬁeld device is to use a DC sourcing output

module as shown below. The Darlington NPN stage will have about 1.5 V ON-state saturation,

but this is not a problem with low-current solid-state loads.

Field Device

Output

Ground

Input

Common

PLC DC Sourcing Output

+DC pwr

–

(sourcing)

(sinking)

Supply

input

Field Device

Output

Ground

Input

Common

PLC DC Output

+DC pwr

–

(sourcing)

(sinking)

Power

(sinking)

pull-up

Supply

input

pull-up

Rinput

=supply

V – 0.7 –

input

I=input (turn–on)

input

pull-up

P=supply

pullup

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–25

Chapter 8: Installation and Wiring

Relay Output Guidelines

Several output modules in the Do-more I/O family feature relay outputs: D2–04TRS,

D2–08TR, D2–12TR, D2–08CDR, F2–08TR and F2–08TRS. Relays are best for the

following applications:

• Loads that require higher currents than the solid-state outputs can deliver

• Cost-sensitive applications

• Some output channels need isolation from other outputs (such as when some loads require different

voltages than other loads)

Some applications in which NOT to use relays:

• Loads that require currents under 10mA

• Loads which must be switched at high speed or heavy duty cycle

Relay outputs in the Do-more output modules are available in two

contact arrangements, shown to the right. The Form A type, or

SPST (single pole, single throw) type, is normally open and is the

simplest to use. The Form C type, or SPDT (single pole, double

throw) type, has a center contact which moves and a stationary

contact on either side. This provides a normally closed contact

and a normally open contact.

Some relay output module’s relays share common terminals,

which connect to the wiper contact in each relay of the bank.

Other relay modules have relays which are completely isolated

from each other. In all cases, the module drives the relay coil

when the corresponding output point is on.

Relay with Form A contacts

Relay with Form C contacts

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–26

Chapter 8: Installation and Wiring

Relay Outputs – Transient Suppression for Inductive Loads in a Control System

The following pages are intended to give a quick overview of the negative effects of transient

voltages on a control system and provide some simple advice on how to effectively minimize

them. The need for transient suppression is often not apparent to the newcomers in the

automation world. Many mysterious errors that can afﬂict an installation can be traced back

to a lack of transient suppression.

What is a Transient Voltage and Why is it Bad?

Inductive loads (devices with a coil) generate transient voltages as they transition from being

energized to being de-energized. If not suppressed, the transient can be many times greater

than the voltage applied to the coil. These transient voltages can damage PLC outputs or other

electronic devices connected to the circuit, and cause unreliable operation of other electronics

in the general area. Transients must be managed with suppressors for long component life and

reliable operation of the control system.

This example shows a simple circuit with a small 24V/125mA/3W relay. As you can see, when

the switch is opened, thereby de-energizing the coil, the transient voltage generated across the

switch contacts peaks at 140V!

In the same circuit, replacing the relay with a larger 24V/290mA/7W relay will generate a

transient voltage exceeding 800V (not shown). Transient voltages like this can cause many

problems, including:

• Relay contacts driving the coil may experience arcing, which can pit the contacts and reduce the

relay’s lifespan.

• Solid state (transistor) outputs driving the coil can be damaged if the transient voltage exceeds the

transistor’s ratings. In extreme cases, complete failure of the output can occur the very ﬁrst time a

coil is de-energized.

• Input circuits, which might be connected to monitor the coil or the output driver, can also be

damaged by the transient voltage.

A very destructive side-effect of the arcing across relay contacts is the electromagnetic

interference (EMI) it can cause. This occurs because the arcing causes a current surge, which

releases RF energy. The entire length of wire between the relay contacts, the coil, and the

power source carries the current surge and becomes an antenna that radiates the RF energy. It

will readily couple into parallel wiring and may disrupt the PLC and other electronics in the

area. This EMI can make an otherwise stable control system behave unpredictably at times.

Oscilloscope

Relay Coil

(24V/125mA/3W,

AutomationDirect part no.

750-2C-24D)

24 VDC

160

140

120

100

-20

Volts

Example: Circuit with no Suppression

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–27

Chapter 8: Installation and Wiring

PLC’s Integrated Transient Suppressors

Although the PLC’s outputs typically have integrated suppressors to protect against transients,

they are not capable of handling them all. It is usually necessary to have some additional

transient suppression for an inductive load.

Here is another example using the same 24V/125mA/3W relay used earlier. This example

measures the PNP transistor output of a D0-06DD2 PLC, which incorporates an integrated

Zener diode for transient suppression. Instead of the 140V peak in the ﬁrst example, the

transient voltage here is limited to about 40V by the Zener diode. While the PLC will probably

tolerate repeated transients in this range for some time, the 40V is still beyond the module’s

peak output voltage rating of 30V.

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Example: Small Inductive Load with Only Integrated Suppression

The next example uses the same circuit as above, but with a larger 24V/290mA/7W relay,

thereby creating a larger inductive load. As you can see, the transient voltage generated is much

worse, peaking at over 50V. Driving an inductive load of this size without additional transient

suppression is very likely to permanently damage the PLC output.

Example: Larger Inductive Load with Only Integrated Suppression

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Additional transient suppression should be used in both these examples. If you are unable to

measure the transients generated by the connected loads of your control system, using additional

transient suppression on all inductive loads would be the safest practice.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–28

Chapter 8: Installation and Wiring

Types of Additional Transient Protection

DC Coils:

The most effective protection against transients from a DC coil is a ﬂyback diode. A ﬂyback

diode can reduce the transient to roughly 1V over the supply voltage, as shown in this example.

Oscilloscope

24 VDC

DC Flyback Circuit

Sinking

Sourcing

-5

Volts

Many AutomationDirect socketed relays and motor starters have add-on ﬂyback diodes

that plug or screw into the base, such as the AD-ASMD-250 protection diode module and

784-4C-SKT-1 socket module shown below. If an add-on ﬂyback diode is not available for

your inductive load, an easy way to add one is to use AutomationDirect’s DN-D10DR-A

diode terminal block, a 600VDC power diode mounted in a slim DIN rail housing.

DN-D10DR-A

Diode Terminal Block

AD-ASMD-250

Protection Diode Module

784-4C-SKT-1

Relay Socket

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M 8–29

Chapter 8: Installation and Wiring

24 VDC

DC MOV or TVS Diode Circuit

Sinking

Sourcing

ZL-TSD8-24

Transorb Module

AC Coils:

Two options for AC coils are MOVs or bi-directional TVS diodes. These devices are most

effective at protecting the driver from a transient voltage when connected across the driver

(PLC output) but are also commonly connected across the coil. The optimum voltage rating

for the suppressor is the lowest rated voltage available that will NOT conduct at the supply

voltage, while allowing a safe margin.

AutomationDirect’s ZL-TSD8-120 transorb module is a good choice for 120VAC circuits. It

is a bank of eight bi-directional 180V TVS diodes.

VAC

C MOV or Bi-Directional Diode Circuit

ZL-TSD8-120

Transorb Module

NOTE: Manufacturers of devices with coils frequently offer MOV or TVS diode suppressors as an add-

on option which mount conveniently across the coil. Before using them, carefully check the suppressor

ratings. Just because the suppressor is made speciﬁcally for that part does not mean it will reduce the

transient voltages to an acceptable level.

For example, a MOV or TVS diode rated for use on 24–48 VDC coils would need to have a

high enough voltage rating to NOT conduct at 48V. That suppressor might typically start

conducting at roughly 60VDC. If it were mounted across a 24V coil, transients of roughly

84V (if sinking output) or -60V (if sourcing output) could reach the PLC output. Many

semiconductor PLC outputs cannot tolerate such levels.

Two more common options for DC coils are Metal Oxide Varistors (MOV) or TVS diodes.

These devices should be connected across the driver (PLC output) for best protection as shown

below. The optimum voltage rating for the suppressor is the lowest rated voltage available that

will NOT conduct at the supply voltage, while allowing a safe margin.

AutomationDirect’s ZL-TSD8-24 transorb module is a good choice for 24VDC circuits. It is

a bank of 8 uni-directional 30V TVS diodes. Since they are uni-directional, be sure to observe

the polarity during installation. MOVs or bi-directional TVS diodes would install at the same

location, but have no polarity concerns.

Do-more H2 Series PLC User Manual, 1st Edition, Rev. E - H2-DM-M

8–30

Chapter 8: Installation and Wiring

Notes:

Chapter 8 Ch8

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