MaxStream XBEE2 XBEE SERIES 2 OEM RF MODULE User Manual XBee XBee PRO ZB RF Modules

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Date Submitted	2011-11-25 00:00:00
Date Available	2011-11-25 00:00:00
Creation Date	2011-11-10 13:40:28
Producing Software	Acrobat Distiller 9.0.0 (Windows)
Document Lastmod	2011-11-10 13:53:06
Document Title	XBee/XBee-PRO ZB RF Modules
Document Creator	FrameMaker 9.0
Document Author:	Digi International

XBee®/XBee-PRO® ZB RF Modules
ZigBee RF Modules by Digi International
Models: XBEE2, XBEEPRO2, PRO S2B
Hardware: S2 and S2B
Firmware Versions:
- 20xx - Coordinator - AT/Transparent Operation
- 21xx - Coordinator - API Operation
- 22xx - Router - AT/Transparent Operation
- 23xx - Router - API Operation
- 28xx - End Device - AT/Transparent Operation
- 29xx - End Device - API Operation
Draft
Digi International Inc.
11001 Bren Road East
Minnetonka, MN 55343
877 912-3444 or 952 912-3444
http://www.digi.com
90000976_J
November
XBee®/XBee‐PRO® ZB RF Modules
© 2011 Digi International, Inc. All rights reserved
No part of the contents of this manual may be transmitted or reproduced in any
form or by any means without the written permission of Digi International, Inc.
ZigBee® is a registered trademark of the ZigBee Alliance.
XBee® and XBee‐PRO® are registered trademarks of Digi International, Inc.
Technical Support:
Phone:
(866) 765-9885 toll-free U.S.A. & Canada
(801) 765-9885 Worldwide
8:00 am - 5:00 pm [U.S. Mountain Time]
Live Chat:
www.digi.com
Online Support:
http://www.digi.com/support/eservice/login.jsp
Email:
rf-experts@digi.com
© 2011 Digi International, Inc.
XBee®/XBee‐PRO® ZB RF Modules
Contents
Overview 6
What's New in 2x7x 6
Firmware 6
Manual 7
Key Features 8
Worldwide Acceptance 8
Specifications 9
Hardware Specs for Programmable Variant 10
Mechanical Drawings 10
SIF Header Interface 11
Mounting Considerations 12
Pin Signals 13
EM250 Pin Mappings 14
Design Notes 14
Power Supply Design 14
Recommended Pin Connections 15
Board Layout 15
Electrical Characteristics 17
Module Operation for Programmable Variant 17
XBEE Programmable Bootloader 19
Overview 19
Bootloader Software Specifics 19
Bootloader Menu Commands 23
Firmware Updates 24
Output File configuration 25
RF Module Operation 26
Serial Communications 26
UART Data Flow 26
Serial Buffers 26
Serial Flow Control 27
Serial Interface Protocols 28
Modes of Operation 30
Operating Channel 35
ZigBee Application Layers: In Depth 35
Application Support Sublayer (APS) 35
Application Profiles 35
Coordinator Operation 36
Forming a Network 36
Channel Selection 36
PAN ID Selection 36
Security Policy 37
Persistent Data 37
XBee ZB Coordinator Startup 37
Permit Joining 38
Resetting the Coordinator 38
Leaving a Network 38
Replacing a Coordinator (Security Disabled Only) 39
Example: Starting a Coordinator 39
Example: Replacing a Coordinator (security disabled) 40
Router Operation 40
Discovering ZigBee Networks 40
Joining a Network 40
Authentication 40
Persistent Data 41
XBee ZB Router Joining 41
Permit Joining 43
Joining Always Enabled 43
Joining Temporarily Enabled 43
Router Network Connectivity 43
Leaving a Network 45
Resetting the Router 46
Example: Joining a Network 46
End Device Operation 46
Discovering ZigBee Networks 46
Joining a Network 47
Idle Mode 30
Parent Child Relationship 47
Transmit Mode 30
End Device Capacity 47
Receive Mode 31
Authentication 47
Command Mode 31
Persistent Data 47
Sleep Mode 32
XBee ZigBee Networks 33
Orphan Scans 47
XBee: ZB End Device Joining 48
Introduction to ZigBee 33
Parent Connectivity 49
ZigBee Stack Layers 33
Resetting the End Device 49
Networking Concepts 33
Leaving a Network 49
Device Types 33
PAN ID 34
© 2011 Digi Internaitonal, Inc.
Example: Joining a Network 49
Channel Scanning 50
XBee®/XBee‐PRO® ZB RF Modules
Contents
Managing Multiple ZigBee Networks 50
PAN ID Filtering 50
Preconfigured Security Keys 50
Trust Center 73
Forming and Joining a Secure Network 73
Implementing Security on the XBee 73
Permit Joining 51
Enabling Security 74
Application Messaging 51
Setting the Network Security Key 74
Transmission, Addressing, and Routing 52
Addressing 52
64-bit Device Addresses 52
16-bit Device Addresses 52
Application Layer Addressing 52
Data Transmission 52
Broadcast Transmissions 53
Unicast Transmissions 53
Data Transmission Examples 55
RF Packet Routing 56
Link Status Transmission 57
AODV Mesh Routing 58
Many-to-One Routing 60
Source Routing 60
Encrypted Transmissions 63
Maximum RF Payload Size 63
Throughput 64
ZDO Transmissions 64
ZigBee Device Objects (ZDO) 64
Sending a ZDO Command 65
Receiving ZDO Commands and Responses 65
Transmission Timeouts 66
Unicast Timeout 67
Extended Timeout 67
Transmission Examples 68
Security 70
Security Modes 70
ZigBee Security Model 70
Network Layer Security 70
Frame Counter 71
Message Integrity Code 71
Network Layer Encryption and Decryption 71
Network Key Updates 71
APS Layer Security 71
Message integrity Code 72
APS Link Keys 72
APS Layer Encryption and Decryption 72
Network and APS Layer Encryption 72
© 2011 Digi Internaitonal, Inc.
Setting the APS Trust Center Link Key 74
Enabling APS Encryption 74
Using a Trust Center 74
XBee Security Examples 75
Example 1: Forming a network with security (pre-configured link keys) 75
Example 2: Forming a network with security (obtaining keys during joining) 75
Network Commissioning and Diagnostics 77
Device Configuration 77
Device Placement 77
Link Testing 77
RSSI Indicators 78
Device Discovery 78
Network Discovery 78
ZDO Discovery 78
Joining Announce 78
Commissioning Pushbutton and Associate LED 78
Commissioning Pushbutton 79
Associate LED 80
Managing End Devices 82
End Device Operation 82
Parent Operation 82
End Device Poll Timeouts 83
Packet Buffer Usage 83
Non-Parent Device Operation 83
XBee End Device Configuration 84
Pin Sleep 84
Cyclic Sleep 86
Transmitting RF Data 89
Receiving RF Data 89
IO Sampling 90
Waking End Devices with the Commissioning Pushbutton 90
Parent Verification 90
Rejoining 90
XBee Router/Coordinator Configuration 90
RF Packet Buffering Timeout 91
Child Poll Timeout 91
XBee®/XBee‐PRO® ZB RF Modules
Contents
Transmission Timeout 91
Putting it all Together 92
Short Sleep Periods 92
Extended Sleep Periods 92
Sleep Examples 92
XBee Analog and Digital IO Lines 94
IO Configuration 94
IO Sampling 94
with the API 123
Sending Public Profile Commands with the API 125
XBee Command Reference Tables 128
Module Support 138
Power up Module at 9600 Baud 138
X-CTU Configuration Tool 138
Customizing XBee ZB Firmware 138
Queried Sampling 96
Design Considerations for Digi Drop-In Networking
138
Periodic IO Sampling 96
XBee Bootloader 138
Change Detection Sampling 96
Programming XBee Modules 139
RSSI PWM 96
IO Examples 97
API Operation 98
API Frame Specifications 98
API Examples 100
API UART Exchanges 101
Serial Firmware Updates 139
Invoke XBee Bootloader 139
Send Firmware Image 139
SIF Firmware Updates 140
Writing Custom Firmware 140
Regulatory Compliance 140
AT Commands 101
Enabling GPIO 1 and 2 141
Transmitting and Receiving RF Data 101
Detecting XBee vs. XBee-PRO 141
Remote AT Commands 101
Source Routing 102
Ensuring Optimal Output Power 141
Improving Low Power Current Consumption 142
Supporting the API 102
XBee (non-PRO) Initialization: 142
API Frames 102
When sleeping (end devices): 142
AT Command 102
When waking from sleep (end devices): 142
AT Command - Queue Parameter Value 103
Appendix A:Definitions 144
ZigBee Transmit Request 103
Appendix B: Agency Certifications 146
Explicit Addressing ZigBee Command Frame 105
Appendix C:Migrating from ZNet 2.5 to XBee ZB 154
Remote AT Command Request 107
Create Source Route 108
Appendix D:Additional Information 155
AT Command Response 109
Modem Status 109
ZigBee Transmit Status 110
ZigBee Receive Packet 111
ZigBee Explicit Rx Indicator 112
ZigBee IO Data Sample Rx Indicator 113
XBee Sensor Read Indicator 114
Node Identification Indicator 116
Remote Command Response 117
Over-the-Air Firmware Update Status 118
Route Record Indicator 119
Many-to-One Route Request Indicator 120
Sending ZigBee Device Objects (ZDO) Commands
with the API 121
Sending ZigBee Cluster Library (ZCL) Commands
© 2011 Digi Internaitonal, Inc.
1. Overview
This manual describes the operation of the XBee/XBee-PRO ZB RF module, which
consists of ZigBee firmware loaded onto XBee S2 and S2B hardware, models:
XBEE2, XBEEPRO2 and PRO S2B. The XBee/XBee-PRO ZB RF Modules are
designed to operate within the ZigBee protocol and support the unique needs of
low-cost, low-power wireless sensor networks. The modules require minimal
power and provide reliable delivery of data between remote devices.
The modules operate within the ISM 2.4 GHz frequency band and are compatible
with the following:
•XBee RS-232 Adapter
•XBee RS-485 Adapter
•XBee Analog I/O Adapter
•XBee Digital I/O Adapter
•XBee Sensor
•XBee USB Adapter
•XStick
•ConnectPort X Gateways
•XBee Wall Router.
The XBee/XBee-PRO ZB firmware release can be installed on XBee ZNet or ZB modules. The XBee ZB firmware is based
on the EmberZNet 3.x ZigBee PRO Feature Set mesh networking stack, while the XBee ZNet 2.5 firmware is based on
Ember's proprietary "designed for ZigBee" mesh stack (EmberZNet 2.5.x). ZB and ZNet 2.5 firmware are similar in
nature, but not over-the-air compatible. Devices running ZNet 2.5 firmware cannot talk to devices running the ZB firmware.
What's New in 2x7x
Firmware
XBee/XBee-PRO ZB firmware includes the following new features (compared with 2x6x):
•Using Ember stack version 3.4.1.
•Support for the PRO S2B with temperature compensation and an overvoltage check. Within 15 seconds of
the supply voltage exceeding 3.9V, the API will emit a 0x08 modem status (Overvoltage) message, and 
then the AT/API versions will do a watchdog reset.
•ZDO pass-through added. If AO=3, then ZDO requests which are not supported by the stack will be 
passed out the UART.
•An attempt to send an oversized packet (256+ bytes) will result in a Tx Status message with a status code
of 0x74.
•End devices have two speed polling. 7.5 seconds is the slow rate, which switches to the fast rate to transact with its parent. When transactions are done, it switches back to the slow rate.
•A new receive option bit (0x40) indicates if the packet came from an end device.
•Added extended timeout option since end devices need more time than routers to ack their packets.
•An option bit (0x01) was added to disable APS retries.
•If an end device has not had its polls answered for 5 secs, it will leave and attempt to rejoin the network.
•XBee S2B has a new TP command which returns the temperature compensation sensor reading in units of
Celsius degrees.
•The PP command returns the power dBm setting when PL4 is selected.
•The PO command sets the slow polling rate on end devices. Range is 1-0x1770 in units of 10 msec (10 
msec to 60 sec). Default is 0 which invokes a 100 msec delay.
•Rejoining now can proceed without a NR or NRO command after a Mgmt_Leave_req is processed.
•Command ranges were changed for the SC, IR, and LT commands.
•A PAN ID corruption problem was fixed.
See the 2x7x release notes for a complete list of new features and bug fixes at www.digi.com/support.
© 2011 Digi International, Inc.
XBee®/XBee‐PRO® ZB RF Modules
Manual
The XBee/XBee-PRO/S2B ZB 2x7x manual includes the following corrections over the 2x6x manual:
•Descriptions and specification for the PRO S2B.
•SIF Header Interface, pin 8 relabeled as pin 10.
•Pin mappings for pins 22 and 24 updated.
•New modem status codes were added.
•Corrections to the ZigBee Receive Packet description.
•Description changes for the SC, PL, PP, AO, IR, %V, and PO commands.
•Updates to Appendix B.
© 2011 Digi International, Inc.
XBee®/XBee‐PRO® ZB RF Modules
Key Features
High Performance, Low Cost
XBee
Low Power
XBee
• Indoor/Urban: up to 133’ (40 m)
• TX Peak Current: 40 mA (@3.3 V)
• Outdoor line-of-sight: up to 400’ (120 m)
• RX Current: 40 mA (@3.3 V)
• Transmit Power: 2 mW (3 dBm)
• Power-down Current: < 1 A
• Receiver Sensitivity: -96 dBm
XBee-PRO (S2)
• Indoor/Urban: up to 300’ (90 m), 200' (60
m) for International variant
• Outdoor line-of-sight: up to 2 miles (3200
m), 5000' (1500 m) for International variant
• Transmit Power: 50mW (17dBm), 10mW
(10dBm) for International variant
• Receiver Sensitivity: -102 dBm
XBee-PRO (S2B)
• Indoor/Urban: up to 300’ (90 m), 200' (60
m) for International variant
• Outdoor line-of-sight: up to 2 miles (3200
m), 5000' (1500 m) for International variant
• Transmit Power: 63mW (18dBm), 10mW
(10dBm) for International variant
• Receiver Sensitivity: -102 dBm
Advanced Networking & Security
XBee-PRO (S2)
• TX Peak Current: 295mA (170mA for
international variant)
• RX Current: 45 mA (@3.3 V)
• Power-down Current: 3.5 A typical
@ 25 degrees C
XBee-PRO (S2B)
• TX Peak Current: 205mA (117mA for 
international variant)
• RX Current: 47 mA (@3.3 V)
• Power-down Current: 3.5 A typical 
@ 25 degrees C
Easy-to-Use
No configuration necessary for out-of box
RF communications
AT and API Command Modes for 
configuring module parameters
Small form factor
Retries and Acknowledgements
Extensive command set
DSSS (Direct Sequence Spread Spectrum)
Free X-CTU Software
(Testing and configuration software)
Each direct sequence channel has over
65,000 unique network addresses available
Free & Unlimited Technical Support
Point-to-point, point-to-multipoint 
and peer-to-peer topologies supported
Self-routing, self-healing and fault-tolerant
mesh networking
Worldwide Acceptance
FCC Approval (USA) Refer to Appendix A for FCC Requirements. Systems that contain XBee®/
XBee-PRO® ZB RF Modules inherit Digi Certifications.
ISM (Industrial, Scientific & Medical) 2.4 GHz frequency band
Manufactured under ISO 9001:2000 registered standards
XBee®/XBee-PRO® ZB RF Modules are optimized for use in US, Canada, Europe, Australia, and
Japan (contact Digi for complete list of agency approvals).
© 2011 Digi International, Inc.
XBee®/XBee‐PRO® ZB RF Modules
Specifications
Specifications of the XBee®/XBee‐PRO® ZB RF Module
Specification
XBee
XBee-PRO (S2)
XBee-PRO (S2B)
Indoor/Urban Range
up to 133 ft. (40 m)
Up to 300 ft. (90 m), up to 200 ft (60 m) Up to 300 ft. (90 m), up to 200 ft (60 m)
international variant
international variant
Outdoor RF line-of-sight
Range
up to 400 ft. (120 m)
Up to 2 miles (3200 m), up to 5000 ft
(1500 m) international variant
Transmit Power Output
2mW (+3dBm), boost mode enabled 50mW (+17 dBm)
1.25mW (+1dBm), boost mode
10mW (+10 dBm) for International
disabled
variant
63mW (+18 dBm)
10mW (+10 dBm) for International variant
RF Data Rate
250,000 bps
250,000 bps
250,000 bps
Data Throughput
up to 35000 bps (see chapter 4)
up to 35000 bps (see chapter 4)
up to 35000 bps (see chapter 4)
1200 bps - 1 Mbps
(non-standard baud rates also
supported)
1200 bps - 1 Mbps
(non-standard baud rates also supported)
-96 dBm, boost mode enabled
-95 dBm, boost mode disabled
-102 dBm
-102 dBm
Supply Voltage
2.1 - 3.6 V
3.0 - 3.4 V
2.7 - 3.6 V
Operating Current
(Transmit, max output
power)
40mA (@ 3.3 V, boost mode
enabled)
35mA (@ 3.3 V, boost mode
disabled)
295mA (@3.3 V)
170mA (@3.3 V) international variant
205mA, up to 220 mA with programmable
variant (@3.3 V)
117mA, up to 132 mA with programmable
variant (@3.3 V), International variant
Operating Current
(Receive))
40mA (@ 3.3 V, boost mode
enabled)
38mA (@ 3.3 V, boost mode
disabled)
45 mA (@3.3 V)
47 mA, up to 62 mA with programmable
variant (@3.3 V)
15mA
15mA
< 1 uA @ 25oC
3.5 A typical @ 25oC
3.5 A typical @ 25oC
Operating Frequency
Band
ISM 2.4 GHz
ISM 2.4 GHz
ISM 2.4 GHz
Dimensions
0.960” x 1.087” (2.438cm x 2.761cm) 0.960 x 1.297 (2.438cm x 3.294cm)
0.960 x 1.297 (2.438cm x 3.294cm)
Operating Temperature
-40 to 85º C (industrial)
-40 to 85º C (industrial)
Antenna Options
Integrated Whip Antenna, Embedded
Integrated Whip, Embedded PCB
PCB Antenna, RPSMA or U.FL
Antenna, RPSMA, or U.FL Connector
Connector
Performance
1200 bps - 1 Mbps
Serial Interface Data Rate
(non-standard baud rates also
(software selectable)
supported)
Receiver Sensitivity
Up to 2 miles (3200 m), up to 5000 ft (1500
m) international variant
Power Requirements
Idle Current (Receiver off) 15mA
Power-down Current
General
-40 to 85º C (industrial)
Integrated Whip Antenna, Embedded PCB
Antenna, RPSMA or U.FL Connector
Networking & Security
Supported Network
Topologies
Point-to-point, Point-to-multipoint,
Peer-to-peer, and Mesh
Point-to-point, Point-to-multipoint, Peer- Point-to-point, Point-to-multipoint, Peer-toto-peer, and Mesh
peer, and Mesh
Number of Channels
16 Direct Sequence Channels
14 Direct Sequence Channels
15 Direct Sequence Channels
Channels
11 to 26
11 to 24
11 to 25
Addressing Options
PAN ID and Addresses, Cluster IDs
and Endpoints (optional)
PAN ID and Addresses, Cluster IDs and PAN ID and Addresses, Cluster IDs and
Endpoints (optional)
Endpoints (optional)
United States (FCC Part
15.247)
FCC ID: OUR-XBEE2
FCC ID: MCQ-XBEEPRO2
FCC ID: MCQ-PROS2B
Industry Canada (IC)
IC: 4214A-XBEE2
IC: 1846A-XBEEPRO2
IC: 1846A-PROS2B
Europe (CE)
ETSI
ETSI (International variant)
ETSI (10 mW max)
Agency Approvals
© 2011 Digi International, Inc.
XBee®/XBee‐PRO® ZB RF Modules
Specifications of the XBee®/XBee‐PRO® ZB RF Module
Specification
XBee
XBee-PRO (S2)
XBee-PRO (S2B)
Australia
C-Tick
C-Tick
C-Tick
Japan
R201WW07215215
R201WW08215142 (international
variant)
R201WW10215062 (international variant)
RoHS
Compliant
Compliant
Compliant
Hardware Specs for Programmable Variant
The following specifications need to be added to the current measurement of the previous table if the module
has the programmable secondary processor. For example, if the secondary processor is running and
constantly collecting DIO samples at a rate while having the RF portion of the XBEE sleeping the new current
will be I total = Ir2 + I0, where Ir2 is the runtime current of the secondary processor and Is is the sleep current
of the RF portion of the module of the XBEE-PRO (S2B) listed in the table below.
Specifications of the programmable secondary processor
Optional Secondary Processor Specification
These numbers add to S2B specifications
(Add to RX, TX, and sleep currents depending on
mode of operation)
Runtime current for 32k running at 20MHz
+14mA
Runtime current for 32k running at 1MHz
+1mA
Sleep current
+0.5uA typical
For additional specifications see Freescale Datasheet and
Manual
MC9S08QE32
Minimum Reset low pulse time for EM250
+50 nS (additional resistor increases minimum time)
VREF Range
1.8VDC to VCC
Mechanical Drawings
Mechanical drawings of the XBee®/XBee‐PRO® ZB RF Modules (antenna options not shown)
© 2011 Digi International, Inc.
10
XBee®/XBee‐PRO® ZB RF Modules
Mechanical Drawings for the RPSMA Variant
SIF Header Interface
The XBee/XBee-PRO ZB modules include a SIF programming header that can be used with Ember's
programming tools to upload custom firmware images onto the XBee module. The SIF header orientation and
pinout are shown below.
A male header can be populated on the XBee that mates with Ember's 2x5 ribbon cable. The male header and
ribbon cables are available from Samtec:
2x5 Male Header - FTSH-105-01-F-DV-K
2x5 Ribbon Cable - FFSD-05-D-12.00-01-N
© 2011 Digi International, Inc.
11
XBee®/XBee‐PRO® ZB RF Modules
Mounting Considerations
The XBee module was designed to mount into a receptacle (socket) and therefore does not require any
soldering when mounting it to a board. The XBee-PRO Development Kits contain RS-232 and USB interface
boards which use two 20-pin receptacles to receive modules.
XBee‐PRO Module Mounting to an RS‐232 Interface Board.
The receptacles used on Digi development boards are manufactured by Century Interconnect. Several other
manufacturers provide comparable mounting solutions; however, Digi currently uses the following
receptacles:
• Through-hole single-row receptacles - 
Samtec P/N: MMS-110-01-L-SV (or equivalent)
• Through-hole single-row receptacles - 
Mill-Max P/N: 831-43-0101-10-001000
• Surface-mount double-row receptacles - 
Century Interconnect P/N: CPRMSL20-D-0-1 (or equivalent)
• Surface-mount single-row receptacles - 
Samtec P/N: SMM-110-02-SM-S
Digi also recommends printing an outline of the module on the board to indicate the orientation the
module should be mounted.
© 2011 Digi International, Inc.
12
XBee®/XBee‐PRO® ZB RF Modules
Pin Signals
Pin Assignments for the XBee/XBee‐PRO Modules
(Low‐asserted signals are distinguished with a horizontal line above signal name.)
Pin #
Name
Direction
Default State
VCC
Description
Power supply
DOUT
Output
Output
UART Data Out
DIN / CONFIG
Input
Input
UART Data In
DIO12
Both
Disabled
Digital I/O 12
Module Reset (reset pulse must be at least 200
ns)
RX Signal Strength Indicator / Digital IO
RESET
Both
Open-Collector with
pull-up
RSSI PWM / DIO10
Both
Output
DIO11
Both
Input
Digital I/O 11
[reserved]
Disabled
Do not connect
DTR / SLEEP_RQ/ DIO8
Both
Input
Pin Sleep Control Line or Digital IO 8
10
GND
Ground
11
DIO4
Both
Disabled
Digital I/O 4
Clear-to-Send Flow Control or Digital I/O 7. CTS, if
enabled, is an output.
12
CTS / DIO7
Both
Output
13
ON / SLEEP
Output
Output
Module Status Indicator or Digital I/O 9
Not used for EM250. Used for programmable
secondary processor.
For compatibility with other XBEE modules, we
recommend connecting this pin voltage reference
if Analog sampling is desired.
Otherwise, connect to GND.
14
VREF
Input
15
Associate / DIO5
Both
Output
Associated Indicator, Digital I/O 5
16
RTS / DIO6
Both
Input
Request-to-Send Flow Control, Digital I/O 6. RTS,
if enabled, is an input.
17
AD3 / DIO3
Both
Disabled
Analog Input 3 or Digital I/O 3
18
AD2 / DIO2
Both
Disabled
Analog Input 2 or Digital I/O 2
19
AD1 / DIO1
Both
Disabled
Analog Input 1 or Digital I/O 1
20
AD0 / DIO0 /
Commissioning Button
Disabled
Analog Input 0, Digital IO 0, or Commissioning
Button
Both
• Signal Direction is specified with respect to the module
• See Design Notes section below for details on pin connections.
© 2011 Digi International, Inc.
13
XBee®/XBee‐PRO® ZB RF Modules
EM250 Pin Mappings
The following table shows how the EM250 pins are used on the XBee.
EM250 Pin Number XBee Pin Number
13 (Reset)
5*
19 (GPIO 11)
16*
20 (GPIO 12)
12*
21 (GPIO 0)
15
Other Usage
Connected to pin 8 on 2x5 SIF header.
22 (GPIO 1)
XBee
Tied to ground (module identification)
XBee-PRO (S2)
Low-asserting shutdown line for output power compensation circuitry.
XBee-PRO (S2B)
Used to communicate with Temp Sensor and control Shutdown for low power mode.
24 (GPIO 2)
XBee
Not connected. Configured as output low.
XBee-PRO (S2)
Powers the output power compensation circuitry.
XBee-PRO (S2B)
Used to communicate with Temp Sensor and control Shutdown for low power mode.
25 (GPIO 3)
13
26 (GPIO 4 / ADC 0)
20
Connected to pin 9 on 2x5 SIF header.
27 (GPIO 5 / ADC 1)
19
Connected to pin 10 on 2x5 SIF header.
29 (GPIO 6 /ADC 2)
18
30 (GPIO 7 / ADC 3
17
31 (GPIO 8)
32 (GPIO 9)
2*
33 (GPIO 10)
3*
34 (SIF_CLK)
Connected to pin 6 on 2x5 SIF header.
35 (SIF_MISO)
Connected to pin 2 on 2x5 SIF header.
36 (SIF_MOSI)
Connected to pin 4 on 2x5 SIF header.
37 (SIF_LOAD)
Connected to pin 7 on 2x5 SIF header.
40 (GPIO 16)
41 (GPIO 15)
42 (GPIO 14)
43 (GPIO 13)
11
* NOTE: These lines may not go to the external XBEE pins of the module if the programmable secondary processor
is populated.
Design Notes
The XBee modules do not specifically require any external circuitry or specific connections for proper
operation. However, there are some general design guidelines that are recommended for help in
troubleshooting and building a robust design.
Power Supply Design
Poor power supply can lead to poor radio performance especially if the supply voltage is not kept within
tolerance or is excessively noisy. To help reduce noise a 1uF and 8.2pF capacitor are recommended to be
placed as near to pin1 on the PCB as possible. If using a switching regulator for your power supply, switching
frequencies above 500kHz are preferred. Power supply ripple should be limited to a maximum 250mV peak to
peak.
Note – For designs using the programmable modules an additional 10uF decoupling cap is recommended near
pin 1 of the module. The nearest proximity to pin 1 of the 3 caps should be in the following order: 8.2pf, 1uF
followed by 10uF.
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XBee®/XBee‐PRO® ZB RF Modules
Recommended Pin Connections
The only required pin connections are VCC, GND, DOUT and DIN. To support serial firmware updates, VCC,
GND, DOUT, DIN, RTS, and DTR should be connected.
All unused pins should be left disconnected. All inputs on the radio can be pulled high with 30k internal pull-up
resistors using the PR software command. No specific treatment is needed for unused outputs.
For applications that need to ensure the lowest sleep current, inputs should never be left floating. Use internal
or external pull-up or pull-down resistors, or set the unused I/O lines to outputs.
Other pins may be connected to external circuitry for convenience of operation including the Associate LED pin
(pin 15) and the Commissioning pin (pin 20). The Associate LED pin will flash differently depending on the
state of the module to the network, and a pushbutton attached to pin 20 can enable various join functions
without having to send UART commands. Please see the commissioning pushbutton and associate LED section
in chapter 7 for more details. The source and sink capabilities are limited to 4mA for all pins on the module.
The VRef pin (pin 14) is not used on this module. For compatibility with other XBee modules, we recommend
connecting this pin to a voltage reference if analog sampling is desired. Otherwise, connect to GND.
Board Layout
XBee modules do not have any specific sensitivity to nearby processors, crystals or other PCB components.
Other than mechanical considerations, no special PCB placement is required for integrating XBee radios except
for those with integral antennas. In general, Power and GND traces should be thicker than signal traces and be
able to comfortably support the maximum currents.
The radios are also designed to be self sufficient and work with the integrated and external antennas without
the need for additional ground planes on the host PCB. However, considerations should be taken on the choice
of antenna and antenna location. Metal objects that are near an antenna cause reflections and may reduce the
ability for an antenna to efficiently radiate. Using an integral antenna (like a wire whip antenna) in an enclosed
metal box will greatly reduce the range of a radio. For this type of application an external antenna would be a
better choice.
External antennas should be positioned away from metal objects as much as possible. Metal objects next to
the antenna or between transmitting and receiving antennas can often block or reduce the transmission
distance. Some objects that are often overlooked are metal poles, metal studs or beams in structures,
concrete (it is usually reinforced with metal rods), metal enclosures, vehicles, elevators, ventilation ducts,
refrigerators and microwave ovens.
The Wire Whip Antenna should be straight and perpendicular to the ground plane and/or chassis. It should
reside above or away from any metal objects like batteries, tall electrolytic capacitors or metal enclosures. If
the antenna is bent to fit into a tight space, it should be bent so that as much of the antenna as possible is
away from metal. Caution should be used when bending the antenna, since this will weaken the solder joint
where the antenna connects to the module. Antenna elements radiate perpendicular to the direction they
point. Thus a vertical antenna emits across the horizon.
Chip Antennas should not have any ground planes or metal objects above or below the module at the antenna
location. For best results the module should be in a plastic enclosure, instead of metal one. It should be placed
at the edge of the PCB to which it is mounted. The ground, power and signal planes should be vacant
immediately below the antenna section (See drawing for recommended keepout area).
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XBee®/XBee‐PRO® ZB RF Modules
Electrical Characteristics
DC Characteristics of the XBee/XBee‐PRO
Symbol
Parameter
Condition
Min
Typical
Max
Units
VIL
Input Low Voltage
All Digital Inputs
0.2 * VCC
VIH
Input High Voltage
All Digital Inputs
0.8 * VCC
VOL
Output Low Voltage
VCC >= 2.7 V
0.18*VCC
VOH
Output High Voltage
VCC >= 2.7 V
0.82*VCC
IIIN
Input Leakage Current
VIN = VCC or GND, all inputs, per pin
0.5uA
uA
IOHS
Output source current (standard)
All digital outputs except
RSSI/PWM, DIO10, DIO4
mA
IOHH
Output source current (high
current)
RSSI/PWM, DIO10, DIO4 digital outputs
mA
IOLS
Output sink current (standard
All digital inputs except
RSSI/PWM, DIO10, DIO4
mA
IOLH
Output sink current (high current)
RSSI/PWM, DIO10, DIO4 digital outputs
mA
IOH + IOL
Total output current for all I/O pins
All digital outputs
40
mA
VREFI
VREF Internal
EM250 has an internal reference that is
fixed
1.21
VIADC
ADC input voltage range
VREFI
1.19
1.2
RIS
Input impedance
When taking a sample
M Ohm
RI
Input Impedance
When not taking a sample
10
M Ohm
Note – The signal-ended ADC measurements are limited in their range and only guaranteed for accuracy in
the range 0 to VREFI. The nature of the ADC’s internal design allows for measurements outside of this range
(+/- 200mV), but the accuracy of such measurements are not guaranteed.
Module Operation for Programmable Variant
The S2B modules that have the programmable option populated have a secondary processor with 32k of flash
and 2k of RAM. This allows module integrators to put custom code on the XBEE module to fit their own unique
needs. The DIN, DOUT, RTS, CTS, and RESET lines are intercepted by the secondary processor to allow it to be
in control of the data transmitted and received. All other lines are in parallel and can be controlled by either
the EM250 or the MC9S08QE micro (see Block Diagram for details). The EM250 by default has control of
certain lines. These lines can be released by the EM250 by sending the proper command(s) to disable the
desired DIO line(s) (see XBEE Command Reference Tables).
In order for the secondary processor to sample with ADCs, the XBEE pin 14 (VREF) needs to be connected to
a reference voltage.
Digi provides a bootloader that can take care of programming the processor over the air or through the serial
interface. This means that over the air updates can be supported through an XMODEM protocol. The processor
can also be programmed and debugged through a one wire interface BKGD (Pin 8).
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2. RF Module Operation
Serial Communications
The XBee RF Modules interface to a host device through a logic-level asynchronous serial port. Through its serial
port, the module can communicate with any logic and voltage compatible UART; or through a level translator to any
serial device (for example: through a RS-232 or USB interface board).
UART Data Flow
Devices that have a UART interface can connect directly to the pins of the RF module as shown in the figure
below.
System Data Flow Diagram in a UART‐interfaced environment
(Low‐asserted signals distinguished with horizontal line over signal name.)
DIN (data in)
DIN (data in)
DOUT (data out)
DOUT (data out)
Serial Data
Data enters the module UART through the DIN (pin 3) as an asynchronous serial signal. The signal should
idle high when no data is being transmitted.
Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit (high). The
following figure illustrates the serial bit pattern of data passing through the module.
UART data packet 0x1F (decimal number ʺ31ʺ) as transmitted through the RF module
Example Data Format is 8‐N‐1 (bits ‐ parity ‐ # of stop bits)
Serial communications depend on the two UARTs (the microcontroller's and the RF module's) to be
configured with compatible settings (baud rate, parity, start bits, stop bits, data bits).
The UART baud rate, parity, and stop bits settings on the XBee module can be configured with the BD, NB,
and SB commands respectively. See the command table in chapter 10 for details.
Serial Buffers
The XBee modules maintain small buffers to collect received serial and RF data, which is illustrated in the figure
below. The serial receive buffer collects incoming serial characters and holds them until they can be processed.
The serial transmit buffer collects data that is received via the RF link that will be transmitted out the UART.
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XBee®/XBee‐PRO® ZB RF Modules
TInternal Data Flow Diagram
Serial
Receiver
Buffer
DIN
RF TX
Buffer
Transmitter
RF Switch
CTS
Antenna
Port
Processor
DOUT
Serial Transmit
Buffer
RF RX
Buffer
Receiver
RTS
Serial Receive Buffer
When serial data enters the RF module through the DIN Pin (pin 3), the data is stored in the serial receive
buffer until it can be processed. Under certain conditions, the module may not be able to process data in
the serial receive buffer immediately. If large amounts of serial data are sent to the module, CTS flow
control may be required to avoid overflowing the serial receive buffer.
Cases in which the serial receive buffer may become full and possibly overflow:
1.
If the module is receiving a continuous stream of RF data, the data in the serial receive buffer
will not be transmitted until the module is no longer receiving RF data.
2.
If the module is transmitting an RF data packet, the module may need to discover the destination address or establish a route to the destination. After transmitting the data, the module may
need to retransmit the data if an acknowledgment is not received, or if the transmission is a broadcast. These issues could delay the processing of data in the serial receive buffer.
Serial Transmit Buffer
When RF data is received, the data is moved into the serial transmit buffer and sent out the UART. If the
serial transmit buffer becomes full enough such that all data in a received RF packet won’t fit in the serial
transmit buffer, the entire RF data packet is dropped.
Cases in which the serial transmit buffer may become full resulting in dropped RF packets
1. If the RF data rate is set higher than the interface data rate of the module, the module could
receive data faster than it can send the data to the host.
2. If the host does not allow the module to transmit data out from the serial transmit buffer
because of being held off by hardware flow control.
Serial Flow Control
The RTS and CTS module pins can be used to provide RTS and/or CTS flow control. CTS flow control provides an
indication to the host to stop sending serial data to the module. RTS flow control allows the host to signal the
module to not send data in the serial transmit buffer out the uart. RTS and CTS flow control are enabled using
the D6 and D7 commands.
CTS Flow Control
If CTS flow control is enabled (D7 command), when the serial receive buffer is 17 bytes away from being
full, the module de-asserts CTS (sets it high) to signal to the host device to stop sending serial data. CTS is
re-asserted after the serial receive buffer has 34 bytes of space.
RTS Flow Control
If RTS flow control is enabled (D6 command), data in the serial transmit buffer will not be sent out the
DOUT pin as long as RTS is de-asserted (set high). The host device should not de-assert RTS for long
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XBee®/XBee‐PRO® ZB RF Modules
periods of time to avoid filling the serial transmit buffer. If an RF data packet is received, and the serial
transmit buffer does not have enough space for all of the data bytes, the entire RF data packet will be
discarded.
Note: If the XBee is sending data out the UART when RTS is de-asserted (set high), the XBee could send
up to 5 characters out the UART after RTS is de-asserted.
Serial Interface Protocols
The XBee modules support both transparent and API (Application Programming Interface) serial interfaces.
Transparent Operation
When operating in transparent mode, the modules act as a serial line replacement. All UART data received
through the DIN pin is queued up for RF transmission. When RF data is received, the data is sent out
through the DOUT pin. The module configuration parameters are configured using the AT command mode
interface.
Data is buffered in the serial receive buffer until one of the following causes the data to be packetized and
transmitted:
•No serial characters are received for the amount of time determined by the RO (Packetization Timeout) parameter. If RO = 0, packetization begins when a character is received.
•The Command Mode Sequence (GT + CC + GT) is received. Any character buffered in the serial
receive buffer before the sequence is transmitted.
•The maximum number of characters that will fit in an RF packet is received.
RF modules that contain the following firmware versions will support Transparent Mode: 
20xx (AT coordinator), 22xx (AT router), and 28xx (AT end device).
API Operation
API operation is an alternative to transparent operation. The frame-based API extends the level to which a
host application can interact with the networking capabilities of the module. When in API mode, all data
entering and leaving the module is contained in frames that define operations or events within the module.
Transmit Data Frames (received through the DIN pin (pin 3)) include:
•RF Transmit Data Frame
•Command Frame (equivalent to AT commands)
Receive Data Frames (sent out the DOUT pin (pin 2)) include:
•RF-received data frame
•Command response
•Event notifications such as reset, associate, disassociate, etc.
The API provides alternative means of configuring modules and routing data at the host application layer. A
host application can send data frames to the module that contain address and payload information instead
of using command mode to modify addresses. The module will send data frames to the application
containing status packets; as well as source, and payload information from received data packets.
The API operation option facilitates many operations such as the examples cited below:
->
Transmitting data to multiple destinations without entering Command Mode
->
Receive success/failure status of each transmitted RF packet
->
Identify the source address of each received packet
RF modules that contain the following firmware versions will support API operation: 21xx (API coordinator),
23xx (API router), and 29xx (API end device).
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A Comparison of Transparent and API Operation
The following table compares the advantages of transparent and API modes of operation:
Transparent Operation Features
Simple Interface
All received serial data is transmitted unless the module is in command mode.
Easy to support
It is easier for an application to support transparent operation and command mode
API Operation Features
Transmitting RF data to multiple remotes only requires changing the address in the API frame. This
process is much faster than in transparent operation where the application must enter AT command
Easy to manage data
transmissions to multiple mode, change the address, exit command mode, and then transmit data.
destinations
Each API transmission can return a transmit status frame indicating the success or reason for
failure.
Received data frames
indicate the sender's
address
All received RF data API frames indicate the source address.
Advanced ZigBee
addressing support
API transmit and receive frames can expose ZigBee addressing fields including source and
destination endpoints, cluster ID and profile ID. This makes it easy to support ZDO commands and
public profile traffic.
Advanced networking
diagnostics
API frames can provide indication of IO samples from remote devices, and node identification
messages.
Remote Configuration
Set / read configuration commands can be sent to remote devices to configure them as needed
using the API.
As a general rule of thumb, API firmware is recommended when a device:
•sends RF data to multiple destinations
•sends remote configuration commands to manage devices in the network
•receives IO samples from remote devices
•receives RF data packets from multiple devices, and the application needs to know which device sent
which packet
•must support multiple ZigBee endpoints, cluster IDs, and/or profile IDs
•uses the ZigBee Device Profile services.
If the above conditions do not apply (e.g. a sensor node, router, or a simple application), then AT firmware
might be suitable. It is acceptable to use a mixture of devices running API and AT firmware in a network.
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XBee®/XBee‐PRO® ZB RF Modules
Modes of Operation
Idle Mode
When not receiving or transmitting data, the RF module is in Idle Mode. The module shifts into the other modes
of operation under the following conditions:
•Transmit Mode (Serial data in the serial receive buffer is ready to be packetized)
•Receive Mode (Valid RF data is received through the antenna)
•Sleep Mode (End Devices only)
•Command Mode (Command Mode Sequence is issued)
Transmit Mode
When serial data is received and is ready for packetization, the RF module will exit Idle Mode and attempt to
transmit the data. The destination address determines which node(s) will receive the data.
Prior to transmitting the data, the module ensures that a 16-bit network address and route to the destination
node have been established.
If the destination 16-bit network address is not known, network address discovery will take place. If a route is
not known, route discovery will take place for the purpose of establishing a route to the destination node. If a
module with a matching network address is not discovered, the packet is discarded. The data will be transmitted
once a route is established. If route discovery fails to establish a route, the packet will be discarded.
Transmit Mode Sequence
Successful
Transmission
Idle Mode
New
Transmission
16-bit Network
Address Known?
Route Known?
16-bit Network
Address Discovery
No
Transmit Data
No
No
16-bit Network
Address Discovered?
Yes
Yes
Route Discovery
Yes
Route Discovered?
Yes
No
Data Discarded
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XBee®/XBee‐PRO® ZB RF Modules
When data is transmitted from one node to another, a network-level acknowledgement is transmitted back
across the established route to the source node. This acknowledgement packet indicates to the source node that
the data packet was received by the destination node. If a network acknowledgement is not received, the
source node will re-transmit the data.
It is possible in rare circumstances for the destination to receive a data packet, but for the source to not receive
the network acknowledgment. In this case, the source will retransmit the data, which could cause the
destination to receive the same data packet multiple times. The XBee modules do not filter out duplicate
packets. The application should include provisions to address this potential issue
See Data Transmission and Routing in chapter 4 for more information.
Receive Mode
If a valid RF packet is received, the data is transferred to the serial transmit buffer.
Command Mode
To modify or read RF Module parameters, the module must first enter into Command Mode - a state in which
incoming serial characters are interpreted as commands. Refer to the API Mode section in chapter 9 for an
alternate means of configuring modules.
AT Command Mode
To Enter AT Command Mode:
Send the 3-character command sequence “+++” and observe guard times before and after the command characters. [Refer to the “Default AT Command Mode Sequence” below.]
Default AT Command Mode Sequence (for transition to Command Mode):
•No characters sent for one second [GT (Guard Times) parameter = 0x3E8]
•Input three plus characters (“+++”) within one second [CC (Command Sequence Character) parameter = 0x2B.]
•No characters sent for one second [GT (Guard Times) parameter = 0x3E8]
Once the AT command mode sequence has been issued, the module sends an "OK\r" out the DOUT pin. The
"OK\r" characters can be delayed if the module has not finished transmitting received serial data.
When command mode has been entered, the command mode timer is started (CT command), and the
module is able to receive AT commands on the DIN pin.
All of the parameter values in the sequence can be modified to reflect user preferences.
NOTE: Failure to enter AT Command Mode is most commonly due to baud rate mismatch. By default,
the BD (Baud Rate) parameter = 3 (9600 bps).
To Send AT Commands:
Send AT commands and parameters using the syntax shown below.
Figure 2‐01. Syntax for sending AT Commands
To read a parameter value stored in the RF module’s register, omit the parameter field.
The preceding example would change the RF module Destination Address (Low) to “0x1F”. To store the new
value to non-volatile (long term) memory, subsequently send the WR (Write) command.
For modified parameter values to persist in the module’s registry after a reset, changes must be saved to
non-volatile memory using the WR (Write) Command. Otherwise, parameters are restored to previously
saved values after the module is reset.
Command Response
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When a command is sent to the module, the module will parse and execute the command. Upon
successful execution of a command, the module returns an “OK” message. If execution of a command
results in an error, the module returns an “ERROR” message.
Applying Command Changes
Any changes made to the configuration command registers through AT commands will not take effect until
the changes are applied. For example, sending the BD command to change the baud rate will not change
the actual baud rate until changes are applied. Changes can be applied in one of the following ways:
•The AC (Apply Changes) command is issued.
•AT command mode is exited.
To Exit AT Command Mode:
1. Send the ATCN (Exit Command Mode) command (followed by a carriage return).
[OR]
2. If no valid AT Commands are received within the time specified by CT (Command Mode Timeout)
Command, the RF module automatically returns to Idle Mode.
For an example of programming the RF module using AT Commands and descriptions of each configurable parameter, please see the Command Reference Table chapter.
Sleep Mode
Sleep modes allow the RF module to enter states of low power consumption when not in use. The XBee RF
modules support both pin sleep (sleep mode entered on pin transition) and cyclic sleep (module sleeps for a
fixed time). XBee sleep modes are discussed in detail in chapter 6.
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3. XBee ZigBee Networks
Introduction to ZigBee
ZigBee is an open global standard built on the IEEE 802.15.4 MAC/PHY. ZigBee defines a network layer above the
802.15.4 layers to support advanced mesh routing capabilities. The ZigBee specification is developed by a growing
consortium of companies that make up the ZigBee Alliance. The Alliance is made up of over 300 members, including
semiconductor, module, stack, and software developers.
ZigBee Stack Layers
The ZigBee stack consists of several layers including the PHY, MAC, Network, Application Support Sublayer (APS),
and ZigBee Device Objects (ZDO) layers. Technically, an Application Framework (AF) layer also exists, but will be
grouped with the APS layer in remaining discussions. The ZigBee layers are shown in the figure below.
A description of each layer appears in the following table:
ZigBee Layer
Description
PHY
Defines the physical operation of the ZigBee device
including receive sensitivity, channel rejection, output
power, number of channels, chip modulation, and
transmission rate specifications. Most ZigBee
applications operate on the 2.4 GHz ISM band at a
250kbps data rate. See the IEEE 802.15.4
specification for details.
MAC
Manages RF data transactions between neighboring
devices (point to point). The MAC includes services
such as transmission retry and acknowledgment
management, and collision avoidance techniques
(CSMA-CA).
Network
Adds routing capabilities that allows RF data packets
to traverse multiple devices (multiple "hops") to route
data from source to destination (peer to peer).
APS (AF)
Application layer that defines various addressing
objects including profiles, clusters, and endpoints.
ZDO
Application layer that provides device and service
discovery features and advanced network
management capabilities.
Networking Concepts
Device Types
ZigBee defines three different device types: coordinator, router, and end device.
Node Types / Sample of a Basic ZigBee Network Topology
A coordinator has the following characteristics: it
•Selects a channel and PAN ID (both 64-bit and 16-bit) to start the network
•Can allow routers and end devices to join the network
•Can assist in routing data
•Cannot sleep--should be mains powered
•Can buffer RF data packets for sleeping end device children.
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A router has the following characteristics: it
•Must join a ZigBee PAN before it can transmit, receive, or route data
•After joining, can allow routers and end devices to join the network
•After joining, can assist in routing data
•Cannot sleep--should be mains powered.
•Can buffer RF data packets for sleeping end device children.
An end device has the following characteristics: it
•Must join a ZigBee PAN before it can transmit or receive data
•Cannot allow devices to join the network
•Must always transmit and receive RF data through its parent. Cannot route data.
•Can enter low power modes to conserve power and can be battery-powered.
An example of such a network is shown below:
In ZigBee networks, the coordinator must select a PAN ID (64-bit and 16-bit) and channel to start a network.
After that, it behaves essentially like a router. The coordinator and routers can allow other devices to join the
network and can route data.
After an end device joins a router or coordinator, it must be able to transmit or receive RF data through that
router or coordinator. The router or coordinator that allowed an end device to join becomes the "parent" of the
end device. Since the end device can sleep, the parent must be able to buffer or retain incoming data packets
destined for the end device until the end device is able to wake and receive the data.
PAN ID
ZigBee networks are called personal area networks or PANs. Each network is defined with a unique PAN
identifier (PAN ID). This identifier is common among all devices of the same network. ZigBee devices are either
preconfigured with a PAN ID to join, or they can discovery nearby networks and select a PAN ID to join.
ZigBee supports both a 64-bit and a 16-bit PAN ID. Both PAN IDs are used to uniquely identify a network.
Devices on the same ZigBee network must share the same 64-bit and 16-bit PAN IDs. If multiple ZigBee
networks are operating within range of each other, each should have unique PAN IDs.
The 16-bit PAN ID is used as a MAC layer addressing field in all RF data transmissions between devices in a
network. However, due to the limited addressing space of the 16-bit PAN ID (65,535 possibilities), there is a
possibility that multiple ZigBee networks (within range of each other) could use the same 16-bit PAN ID. To
resolve potential 16-bit PAN ID conflicts, the ZigBee Alliance created a 64-bit PAN ID.
The 64-bit PAN ID (also called the extended PAN ID), is intended to be a unique, non-duplicated value. When a
coordinator starts a network, it can either start a network on a preconfigured 64-bit PAN ID, or it can select a
random 64-bit PAN ID. The 64-bit PAN ID is used during joining; if a device has a preconfigured 64-bit PAN ID,
it will only join a network with the same 64-bit PAN ID. Otherwise, a device could join any detected PAN and
inherit the PAN ID from the network when it joins. The 64-bit PAN ID is included in all ZigBee beacons and is
used in 16-bit PAN ID conflict resolution.
Routers and end devices are typically configured to join a network with any 16-bit PAN ID as long as the 64-bit
PAN ID is valid. Coordinators typically select a random 16-bit PAN ID for their network.
Since the 16-bit PAN ID only allows up to 65,535 unique values, and since the 16-bit PAN ID is randomly
selected, provisions exist in ZigBee to detect if two networks (with different 64-bit PAN IDs) are operating on
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XBee®/XBee‐PRO® ZB RF Modules
the same 16-bit PAN ID. If such a conflict is detected, the ZigBee stack can perform PAN ID conflict resolution to
change the 16-bit PAN ID of the network in order to resolve the conflict. See the ZigBee specification for details.
To summarize, ZigBee routers and end devices should be configured with the 64-bit PAN ID of the network they
want to join. They typically acquire the 16-bit PAN ID when they join a network.
Operating Channel
ZigBee utilizes direct-sequence spread spectrum modulation and operates on a fixed channel. The 802.15.4 PHY
defines 16 operating channels in the 2.4 GHz frequency band. XBee modules support all 16 channels and XBeePRO modules support 14 of the 16 channels.
ZigBee Application Layers: In Depth
This section provides a more in-depth look at the ZigBee application stack layers (APS, ZDO) including a discussion
on ZigBee endpoints, clusters, and profiles. Much of the material in this section can introduce unnecessary details of
the ZigBee stack that are not required in many cases.
Skip this section if
•The XBee does not need to interoperate or talk to non-Digi ZigBee devices
•The XBee simply needs to send data between devices.
Read this section if
•The XBee may talk to non-Digi ZigBee devices
•The XBee requires network management and discovery capabilities of the ZDO layer
•The XBee needs to operate in a public application profile (smart energy, home automation, etc.)
Application Support Sublayer (APS)
The APS layer in ZigBee adds support for application profiles, cluster IDs, and endpoints.
Application Profiles
Application profiles specify various device descriptions including required functionality for various devices. The
collection of device descriptions forms an application profile. Application profiles can be defined as "Public" or
"Private" profiles. Private profiles are defined by a manufacturer whereas public profiles are defined, developed,
and maintained by the ZigBee Alliance. Each application profile has a unique profile identifier assigned by the
ZigBee Alliance.
Examples of public profiles include:
•Home Automation
•Smart Energy
•Commercial Building Automation
The Smart Energy profile, for example, defines various device types including an energy service portal, load
controller, thermostat, in-home display, etc. The Smart Energy profile defines required functionality for each
device type. For example, a load controller must respond to a defined command to turn a load on or off. By
defining standard communication protocols and device functionality, public profiles allow interoperable ZigBee
solutions to be developed by independent manufacturers.
Digi XBee ZB firmware operates on a private profile called the Digi Drop-In Networking profile. However, the API
firmware in the module can be used in many cases to talk to devices in public profiles or non-Digi private
profiles. See the API Operations chapter for details.
Clusters
A cluster is an application message type defined within a profile. Clusters are used to specify a unique
function, service, or action. For example, the following are some clusters defined in the home automation
profile:
•On/Off - Used to switch devices on or off (lights, thermostats, etc.)
•Level Control - Used to control devices that can be set to a level between on and off
•Color Control - Controls the color of color capable devices.
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Each cluster has an associated 2-byte cluster identifier (cluster ID). The cluster ID is included in all
application transmissions. Clusters often have associated request and response messages. For example, a
smart energy gateway (service portal) might send a load control event to a load controller in order to
schedule turning on or off an appliance. Upon executing the event, the load controller would send a load
control report message back to the gateway.
Devices that operate in an application profile (private or public) must respond correctly to all required
clusters. For example, a light switch that will operate in the home automation public profile must correctly
implement the On/Off and other required clusters in order to interoperate with other home automation
devices. The ZigBee Alliance has defined a ZigBee Cluster Library (ZCL) that contains definitions or various
general use clusters that could be implemented in any profile.
XBee modules implement various clusters in the Digi private profile. In addition, the API can be used to
send or receive messages on any cluster ID (and profile ID or endpoint). See the Explicit Addressing ZigBee
Command API frame in chapter 3 for details.
Endpoints
The APS layer includes supports for endpoints. An endpoint can be thought of as a running application,
similar to a TCP/IP port. A single device can support one or more endpoints. Each application endpoint is
identified by a 1-byte value, ranging from 1 to 240. Each defined endpoint on a device is tied to an
application profile. A device could, for example, implement one endpoint that supports a Smart Energy load
controller, and another endpoint that supports other functionality on a private profile.
ZigBee Device Profile
Profile ID 0x0000 is reserved for the ZigBee Device Profile. This profile is implemented on all ZigBee
devices. Device Profile defines many device and service discovery features and network management
capabilities. Endpoint 0 is a reserved endpoint that supports the ZigBee Device Profile. This endpoint is
called the ZigBee Device Objects (ZDO) endpoint.
ZigBee Device Objects (ZDO)
The ZDO (endpoint 0) supports the discovery and management capabilities of the ZigBee Device Profile. A
complete listing of all ZDP services is included in the ZigBee specification. Each service has an associated
cluster ID.
The XBee ZB firmware allows applications to easily send ZDO messages to devices in the network using the
API. See the ZDO Transmissions section in chapter 4 for details.
Coordinator Operation
Forming a Network
The coordinator is responsible for selecting the channel, PAN ID (16-bit and 64-bit), security policy, and stack
profile for a network. Since a coordinator is the only device type that can start a network, each ZigBee network
must have one coordinator. After the coordinator has started a network, it can allow new devices to join the
network. It can also route data packets and communicate with other devices on the network.
To ensure the coordinator starts on a good channel and unused PAN ID, the coordinator performs a series of
scans to discover any RF activity on different channels (energy scan) and to discover any nearby operating PANs
(PAN scan). The process for selecting the channel and PAN ID are described in the following sections.
Channel Selection
When starting a network, the coordinator must select a "good" channel for the network to operate on. To do
this, it performs an energy scan on multiple channels (frequencies) to detect energy levels on each channel.
Channels with excessive energy levels are removed from its list of potential channels to start on.
PAN ID Selection
After completing the energy scan, the coordinator scans its list of potential channels (remaining channels after
the energy scan) to obtain a list of neighboring PANs. To do this, the coordinator sends a beacon request
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(broadcast) transmission on each potential channel. All nearby coordinators and routers (that have already
joined a ZigBee network) will respond to the beacon request by sending a beacon back to the coordinator. The
beacon contains information about the PAN the device is on, including the PAN identifiers (16-bit and 64-bit).
This scan (collecting beacons on the potential channels) is typically called an active scan or PAN scan.
After the coordinator completes the channel and PAN scan, it selects a random channel and unused 16-bit PAN
ID to start on.
Security Policy
The security policy determines which devices are allowed to join the network, and which device(s) can
authenticate joining devices. See chapter 5 for a detailed discussion of various security policies.
Persistent Data
Once a coordinator has started a network, it retains the following information through power cycle or reset
events:
•PAN ID
•Operating channel
•Security policy and frame counter values
•Child table (end device children that are joined to the coordinator).
The coordinator will retain this information indefinitely until it leaves the network. When the coordinator leaves
a network and starts a new network, the previous PAN ID, operating channel, and child table data are lost.
XBee ZB Coordinator Startup
The following commands control the coordinator network formation process.
Network formation commands used by the coordinator to form a network.
Command
Description
ID
Used to determine the 64-bit PAN ID. If set to 0 (default), a random 64-bit PAN ID will be selected.
SC
Determines the scan channels bitmask (up to 16 channels) used by the coordinator when forming a
network. The coordinator will perform an energy scan on all enabled SC channels. It will then perform a
PAN ID scan and then form the network on one of the SC channels.
SD
Set the scan duration period. This value determines how long the coordinator performs an energy scan or
PAN ID scan on a given channel.
ZS
Set the ZigBee stack profile for the network.
EE
Enable or disable security in the network.
NK
Set the network security key for the network. If set to 0 (default), a random network security key will be
used.
KY
Set the trust center link key for the network. If set to 0 (default), a random link key will be used.
EO
Set the security policy for the network.
Once the coordinator starts a network, the network configuration settings and child table data persist through
power cycles as mentioned in the "Persistent Data" section.
When the coordinator has successfully started a network, it
•Allows other devices to join the network for a time (see NJ command)
•Sets AI=0
•Starts blinking the Associate LED
•Sends an API modem status frame ("coordinator started") out the UART (API firmware only).
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These behaviors are configurable using the following commands:
Command
Description
NJ
Sets the permit-join time on the coordinator,
measured in seconds.
D5
Enables the Associate LED functionality.
LT
Sets the Associate LED blink time when
joined. Default is 1 blink per second.
If any of the command values in the network formation commands table changes, the coordinator will leave its
current network and start a new network, possibly on a different channel. Note that command changes must be
applied (AC or CN command) before taking effect.
Permit Joining
The permit joining attribute on the coordinator is configurable with the NJ command. NJ can be configured to
always allow joining, or to allow joining for a short time.
Joining Always Enabled
If NJ=0xFF (default), joining is permanently enabled. This mode should be used carefully. Once a network
has been deployed, the application should strongly consider disabling joining to prevent unwanted joins
from occurring.
Joining Temporarily Enabled
If NJ < 0xFF, joining will be enabled only for a number of seconds, based on the NJ parameter. The timer is
started once the XBee joins a network. Joining will not be re-enabled if the module is power cycled or reset.
The following mechanisms can restart the permit-joining timer:
•Changing NJ to a different value (and applying changes with the AC or CN commands)
•Pressing the commissioning button twice (enables joining for 1 minute)
•Issuing the CB command with a parameter of 2 (software emulation of a 2 button press - enables
joining for 1 minute).
Resetting the Coordinator
When the coordinator is reset or power cycled, it checks its PAN ID, operating channel and stack profile against
the network configuration settings (ID, CH, ZS). It also verifies the saved security policy against the security
configuration settings (EE, NK, KY). If the coordinator's PAN ID, operating channel, stack profile, or security
policy is not valid based on its network and security configuration settings, then the coordinator will leave the
network and attempt to form a new network based on its network formation command values.
To prevent the coordinator from leaving an existing network, the WR command should be issued after all
network formation commands have been configured in order to retain these settings through power cycle or
reset events.
Leaving a Network
There are a couple of mechanisms that will cause the coordinator to leave its current PAN and start a new
network based on its network formation parameter values. These include the following:
•Change the ID command such that the current 64-bit PAN ID is invalid.
•Change the SC command such that the current channel (CH) is not included in the channel mask.
•Change the ZS or any of the security command values (excluding NK).
•Issue the NR0 command to cause the coordinator to leave.
•Issue the NR1 command to send a broadcast transmission, causing all devices in the network to leave and
migrate to a different channel.
•Press the commissioning button 4 times or issue the CB command with a parameter of 4.
•Issue a network leave command.
Note that changes to ID, SC, ZS, and security command values only take effect when changes are applied (AC
or CN commands).
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Replacing a Coordinator (Security Disabled Only)
In rare occasions, it may become necessary to replace an existing coordinator in a network with a new physical
device. If security is not enabled in the network, a replacement XBee coordinator can be configured with the
PAN ID (16-bit and 64-bit), channel, and stack profile settings of a running network in order to replace an
existing coordinator.
NOTE: Having two coordinators on the same channel, stack profile, and PAN ID (16-bit and 64-bit) can cause
problems in the network and should be avoided. When replacing a coordinator, the old coordinator should be
turned off before starting the new coordinator.
To replace a coordinator, the following commands should be read from a device on the network:
AT Command
Description
OP
Read the operating 64-bit PAN
ID.
OI
Read the operating 16-bit PAN
ID.
CH
Read the operating channel.
ZS
Read the stack profile.
Each of the commands listed above can be read from any device on the network. (These parameters will be the
same on all devices in the network.) After reading these commands from a device on the network, these
parameter values should be programmed into the new coordinator using the following commands.
AT Command
Description
ID
Set the 64-bit PAN ID to match
the read OP value.
II
Set the initial 16-bit PAN ID to
match the read OI value.
SC
Set the scan channels bitmask
to enable the read operating
channel (CH command). For
example, if the operating
channel is 0x0B, set SC to
0x0001. If the operating channel
is 0x17, set SC to 0x1000.
ZS
Set the stack profile to match the
read ZS value.
Note: II is the initial 16-bit PAN ID. Under certain conditions, the ZigBee stack can change the 16-bit PAN ID of
the network. For this reason, the II command cannot be saved using the WR command. Once II is set, the
coordinator leaves the network and starts on the 16-bit PAN ID specified by II.
Example: Starting a Coordinator
1. Set SC and ID to the desired scan channels and PAN ID values. (The defaults should suffice.)
2. If SC or ID is changed from the default, issue the WR command to save the changes.
3. If SC or ID is changed from the default, apply changes (make SC and ID changes take effect)
either by sending the AC command or by exiting AT command mode.
4. The Associate LED will start blinking once the coordinator has selected a channel and PAN ID.
5. The API Modem Status frame ("Coordinator Started") is sent out the UART (API firmware only).
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6. Reading the AI command (association status) will return a value of 0, indicating a successful
startup.
7. Reading the MY command (16-bit address) will return a value of 0, the ZigBee-defined 16-bit
address of the coordinator.
After startup, the coordinator will allow joining based on its NJ value.
Example: Replacing a Coordinator (security disabled)
1. Read the OP, OI, CH, and ZS commands on the running coordinator.
2. Set the ID, SC, and ZS parameters on the new coordinator, followed by WR command to save
these parameter values.
3. Turn off the running coordinator.
4. Set the II parameter on the new coordinator to match the read OI value on the old coordinator.
5. Wait for the new coordinator to start (AI=0).
Router Operation
Routers must discover and join a valid ZigBee network before they can participate in a ZigBee network. After a
router has joined a network, it can allow new devices to join the network. It can also route data packets and
communicate with other devices on the network.
Discovering ZigBee Networks
To discover nearby ZigBee networks, the router performs a PAN (or active) scan, just like the coordinator does
when it starts a network. During the PAN scan, the router sends a beacon request (broadcast) transmission on
the first channel in its scan channels list. All nearby coordinators and routers operating on that channel (that are
already part of a ZigBee network) respond to the beacon request by sending a beacon back to the router. The
beacon contains information about the PAN the nearby device is on, including the PAN identifier (PAN ID), and
whether or not joining is allowed. The router evaluates each beacon received on the channel to determine if a
valid PAN is found. A router considers a PAN to be valid if the PAN:
•Has a valid 64-bit PAN ID (PAN ID matches ID if ID > 0)
•Has the correct stack profile (ZS command)
•Is allowing joining.
If a valid PAN is not found, the router performs the PAN scan on the next channel in its scan channels list and
continues scanning until a valid network is found, or until all channels have been scanned. If all channels have
been scanned and a valid PAN was not discovered, all channels will be scanned again.
The ZigBee Alliance requires that certified solutions not send beacon request messages too frequently. To meet
certification requirements, the XBee firmware attempts 9 scans per minute for the first 5 minutes, and 3 scans
per minute thereafter. If a valid PAN is within range of a joining router, it should typically be discovered within a
few seconds.
Joining a Network
Once the router discovers a valid network, it sends an association request to the device that sent a valid beacon
requesting a join on the ZigBee network. The device allowing the join then sends an association response frame
that either allows or denies the join.
When a router joins a network, it receives a 16-bit address from the device that allowed the join. The 16-bit
address is randomly selected by the device that allowed the join.
Authentication
In a network where security is enabled, the router must then go through an authentication process. See the
Security chapter for a discussion on security and authentication.
After the router is joined (and authenticated, in a secure network), it can allow new devices to join the network.
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Persistent Data
Once a router has joined a network, it retains the following information through power cycle or reset events:
•PAN ID
•Operating channel
•Security policy and frame counter values
•Child table (end device children that are joined to the coordinator).
The router will retain this information indefinitely until it leaves the network. When the router leaves a network,
the previous PAN ID, operating channel, and child table data are lost.
XBee ZB Router Joining
When the router is powered on, if it is not already joined to a valid ZigBee network, it immediately attempts to
find and join a valid ZigBee network.
Note: The DJ command can be set to 1 to disable joining. The DJ parameter cannot be written with WR, so a
power cycle always clears the DJ setting.
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The following commands control the router joining process.
Command
Description
ID
Sets the 64-bit PAN ID to join. Setting ID=0 allows the router to join any
64-bit PAN ID.
SC
Set the scan channels bitmask that determines which channels a router
will scan to find a valid network. SC on the router should be set to match
SC on the coordinator. For example, setting SC to 0x281 enables
scanning on channels 0x0B, 0x12, and 0x14, in that order.
SD
Set the scan duration, or time that the router will listen for beacons on
each channel.
ZS
Set the stack profile on the device.
EE
Enable or disable security in the network. This must be set to match the
EE value (security policy) of the coordinator.
KY
Set the trust center link key. If set to 0 (default), the link key is expected to
be obtained (unencrypted) during joining.
Once the router joins a network, the network configuration settings and child table data persist through power
cycles as mentioned in the "Persistent Data" section previously. If joining fails, the status of the last join
attempt can be read in the AI command register.
If any of the above command values change, when command register changes are applied (AC or CN
commands), the router will leave its current network and attempt to discover and join a new valid network.
When a ZB router has successfully joined a network, it:
•Allows other devices to join the network for a time
•Sets AI=0
•Starts blinking the Associate LED
•Sends an API modem status frame ("associated") out the UART (API firmware only).
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These behaviors are configurable using the following commands:
Command
Description
NJ
Sets the permit-join time on
the router, or the time that it
will allow new devices to join
the network, measured in
seconds. If NJ=0xFF, permit
joining will always be enabled.
D5
Enables the Associate LED
functionality.
LT
Sets the Associate LED blink
time when joined. Default is 2
blinks per second (router).
Permit Joining
The permit joining attribute on the router is configurable with the NJ command. NJ can be configured to always
allow joining, or to allow joining for a short time.
Joining Always Enabled
If NJ=0xFF (default), joining is permanently enabled. This mode should be used carefully. Once a network has
been deployed, the application should strongly consider disabling joining to prevent unwanted joins from
occurring.
Joining Temporarily Enabled
If NJ < 0xFF, joining will be enabled only for a number of seconds, based on the NJ parameter. The timer is
started once the XBee joins a network. Joining will not be re-enabled if the module is power cycled or reset. The
following mechanisms can restart the permit-joining timer:
•Changing NJ to a different value (and applying changes with the AC or CN commands)
•Pressing the commissioning button twice (enables joining for 1 minute)
•Issuing the CB command with a parameter of 2 (software emulation of a 2 button press - enables joining
for 1 minute)
•Causing the router to leave and rejoin the network.
Router Network Connectivity
Once a router joins a ZigBee network, it remains connected to the network on the same channel and PAN ID as
long as it is not forced to leave. (See Leaving a Network section for details.) If the scan channels (SC), PAN ID
(ID) and security settings (EE, KY) do not change after a power cycle, the router will remain connected to the
network after a power cycle.
If a router may physically move out of range of the network it initially joined, the application should include
provisions to detect if the router can still communicate with the original network. If communication with the
original network is lost, the application may choose to force the router to leave the network (see Leaving a
Network section for details). The XBee firmware includes two provisions to automatically detect the presence of
a network, and leave if the check fails.
Power-On Join Verification
The JV command (join verification) enables the power-on join verification check. If enabled, the XBee will
attempt to discover the 64-bit address of the coordinator when it first joins a network. Once it has joined, it
will also attempt to discover the 64-bit address of the coordinator after a power cycle event. If 3 discovery
attempts fail, the router will leave the network and try to join a new network. Power-on join verification is
disabled by default (JV defaults to 0).
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Network Watchdog
The NW command (network watchdog timeout) can be used for a powered router to periodically check for
the presence of a coordinator to verify network connectivity. The NW command specifies a timeout in
minutes where the router must receive communication from the coordinator or data collector. The following
events restart the network watchdog timer:
•RF data received from the coordinator
•RF data sent to the coordinator and an acknowledgment was received
•Many-to-one route request was received (from any device)
•Changing the value of NW.
If the watchdog timer expires (no valid data received for NW time), the router will attempt to discover the
64-bit address of the coordinator. If the address cannot be discovered, the router records one watchdog
timeout. Once three consecutive network watchdog timeouts have expired (3 * NW) and the coordinator
has not responded to the address discovery attempts, the router will leave the network and attempt to join
a new network. Anytime a router receives valid data from the coordinator or data collector, it will clear the
watchdog timeouts counter and restart the watchdog timer. The watchdog timer (NW command) is settable
to several days. The network watchdog feature is disabled by default (NW defaults to 0).
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Network Watchdog Behavior
Clear Network Watchdog Failure Count
Restart Network Watchdog Timer
Yes
Received RF
Communication from
Coordinator or Data
Collector
No
No
Network Watchdog
Timer Expired?
Yes
Discover Coordinator
Network
Watchdog
Failure Count
=3?
Yes
Coordinator
Found?
No
Network Watchdog Failure
Count +=1
No
Yes
Leave
Leaving a Network
There are a couple of mechanisms that will cause the router to leave its current PAN and attempt to discover
and join a new network based on its network joining parameter values.
These include the following:
•Change the ID command such that the current 64-bit PAN ID is invalid.
•Change the SC command such that the current channel (CH) is not included in the channel mask.
•Change the ZS or any of the security command values.
•Issue the NR0 command to cause the router to leave.
•Issue the NR1 command to send a broadcast transmission, causing all devices in the network to leave and
migrate to a different channel.
•Press the commissioning button 4 times or issue the CB command with a parameter of 4.
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•Issue a network leave command.
Note that changes to ID, SC, ZS, and security command values only take effect when changes are applied (AC
or CN commands).
Resetting the Router
When the router is reset or power cycled, it checks its PAN ID, operating channel and stack profile against the
network configuration settings (ID, SC, ZS). It also verifies the saved security policy is valid based on the
security configuration commands (EE, KY). If the router's PAN ID, operating channel, stack profile, or security
policy is invalid, the router will leave the network and attempt to join a new network based on its network
joining command values.
To prevent the router from leaving an existing network, the WR command should be issued after all network
joining commands have been configured in order to retain these settings through power cycle or reset events.
Example: Joining a Network
After starting a coordinator (that is allowing joins), the following steps will cause a router to join the network:
1. Set ID to the desired 64-bit PAN ID, or to 0 to join any PAN.
2. Set SC to the list of channels to scan to find a valid network.
3. If SC or ID is changed from the default, apply changes (make SC and ID changes take effect)
by issuing the AC or CN command.
4. The Associate LED will start blinking once the router has joined a PAN.
5. If the Associate LED is not blinking, the AI command can be read to determine the cause of join
failure.
6. Once the router has joined, the OP and CH commands will indicate the operating 64-bit PAN ID
and channel the router joined.
7. The MY command will reflect the 16-bit address the router received when it joined.
8. The API Modem Status frame ("Associated") is sent out the UART (API firmware only).
9. The joined router will allow other devices to join for a time based on its NJ setting.
End Device Operation
Similar to routers, end devices must also discover and join a valid ZigBee network before they can participate in
a network. After an end device has joined a network, it can communicate with other devices on the network.
Since end devices are intended to be battery powered and therefore support low power (sleep) modes, end
devices cannot allow other devices to join, nor can they route data packets.
Discovering ZigBee Networks
End devices go through the same process as routers to discover networks by issuing a PAN scan. After sending
the broadcast beacon request transmission, the end device listens for a short time in order to receive beacons
sent by nearby routers and coordinators on the same channel. The end device evaluates each beacon received
on the channel to determine if a valid PAN is found. An end device considers a PAN to be valid if the PAN:
•Has a valid 64-bit PAN ID (PAN ID matches ID if ID > 0)
•Has the correct stack profile (ZS command)
•Is allowing joining
•Has capacity for additional end devices (see End Device Capacity section below).
If a valid PAN is not found, the end device performs the PAN scan on the next channel in its scan channels list
and continues this process until a valid network is found, or until all channels have been scanned. If all channels
have been scanned and a valid PAN was not discovered, the end device may enter a low power sleep state and
scan again later.
If scanning all SC channels fails to discover a valid PAN, XBee ZB modules will attempt to enter a low power
state and will retry scanning all SC channels after the module wakes from sleeping. If the module cannot enter
a low power state, it will retry scanning all channels, similar to the router. To meet ZigBee Alliance
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requirements, the end device will attempt up to 9 scans per minute for the first 5 minutes, and 3 scans per
minute thereafter.
Note: The XBee ZB end device will not enter sleep until it has completed scanning all SC channels for a valid
network.
Joining a Network
Once the end device discovers a valid network, it joins the network, similar to a router, by sending an
association request (to the device that sent a valid beacon) to request a join on the ZigBee network. The device
allowing the join then sends an association response frame that either allows or denies the join.
When an end device joins a network, it receives a 16-bit address from the device that allowed the join. The 16bit address is randomly selected by the device that allowed the join.
Parent Child Relationship
Since an end device may enter low power sleep modes and not be immediately responsive, the end device relies
on the device that allowed the join to receive and buffer incoming messages in its behalf until it is able to wake
and receive those messages. The device that allowed an end device to join becomes the parent of the end
device, and the end device becomes a child of the device that allowed the join.
End Device Capacity
Routers and coordinators maintain a table of all child devices that have joined called the child table. This table is
a finite size and determines how many end devices can join. If a router or coordinator has at least one unused
entry in its child table, the device is said to have end device capacity. In other words, it can allow one or more
additional end devices to join. ZigBee networks should have sufficient routers to ensure adequate end device
capacity.
In the XBee ZB 2x6x firmware, a coordinator can support 10 end devices, and a router can support 12 end
devices.
In ZB firmware, the NC command (number of remaining end device children) can be used to determine how
many additional end devices can join a router or coordinator. If NC returns 0, then the router or coordinator
device has no more end device capacity. (Its child table is full.)
Also of note, since routers cannot sleep, there is no equivalent need for routers or coordinators to track joined
routers. Therefore, there is no limit to the number of routers that can join a given router or coordinator device.
(There is no "router capacity" metric.)
Authentication
In a network where security is enabled, the end device must then go through an authentication process. See
chapter 5 for a discussion on security and authentication.
Persistent Data
The end device can retain its PAN ID, operating channel, and security policy information through a power cycle.
However, since end devices rely heavily on a parent, the end device does an orphan scan to try and contact its
parent. If the end device does not receive an orphan scan response (called a coordinator realignment
command), it will leave the network and try to discover and join a new network. When the end device leaves a
network, the previous PAN ID and operating channel settings are lost.
Orphan Scans
When an end device comes up from a power cycle, it performs an orphan scan to verify it still has a valid parent.
The orphan scan is sent as a broadcast transmission and contains the 64-bit address of the end device. Nearby
routers and coordinator devices that receive the broadcast check their child tables for an entry that contains the
end device's 64-bit address. If an entry is found with a matching 64-bit address, the device sends a coordinator
realignment command to the end device that includes the end device's 16-bit address, 16-bit PAN ID, operating
channel, and the parent's 64-bit and 16-bit addresses.
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If the orphaned end device receives a coordinator realignment command, it is considered joined to the network.
Otherwise, it will attempt to discover and join a valid network.
XBee: ZB End Device Joining
When an end device is powered on, if it is not joined to a valid ZigBee network, or if the orphan scan fails to find
a parent, it immediately attempts to find and join a valid ZigBee network.
Note: The DJ command can be set to 1 to disable joining. The DJ parameter cannot be written with WR, so a
power cycle always clears the DJ setting.
Similar to a router, the following commands control the end device joining process.
Network joining commands used by an end device to join a network.
Command
Description
ID
Sets the 64-bit PAN ID to join. Setting ID=0 allows the router
to join any 64-bit PAN ID.
SC
Set the scan channels bitmask that determines which
channels an end device will scan to find a valid network. SC
on the end device should be set to match SC on the
coordinator and routers in the desired network. For example,
setting SC to 0x281 enables scanning on channels 0x0B,
0x12, and 0x14, in that order.
SD
Set the scan duration, or time that the end device will listen
for beacons on each channel.
ZS
Set the stack profile on the device.
EE
Enable or disable security in the network. This must be set to
match the EE value (security policy) of the coordinator.
KY
Set the trust center link key. If set to 0 (default), the link key
is expected to be obtained (unencrypted) during joining.
Once the end device joins a network, the network configuration settings can persist through power cycles as
mentioned in the "Persistent Data" section previously. If joining fails, the status of the last join attempt can be
read in the AI command register.
If any of these command values changes, when command register changes are applied, the end device will
leave its current network and attempt to discover and join a new valid network.
When a ZB end device has successfully started a network, it
•Sets AI=0
•Starts blinking the Associate LED
•Sends an API modem status frame ("associated") out the UART (API firmware only)
•Attempts to enter low power modes.
These behaviors are configurable using the following commands:
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Command
Description
D5
Enables the Associate LED functionality.
LT
Sets the Associate LED blink time when joined. Default is 2 blinks per
second (end devices).
SM, SP, ST, SN,
SO
Parameters that configure the sleep mode characteristics. (See
Managing End Devices chapter for details.)
Parent Connectivity
The XBee ZB end device sends regular poll transmissions to its parent when it is awake. These poll
transmissions query the parent for any new received data packets. The parent always sends a MAC layer
acknowledgment back to the end device. The acknowledgment indicates whether the parent has data for the
end device or not.
If the end device does not receive an acknowledgment for 3 consecutive poll requests, it considers itself
disconnected from its parent and will attempt to discover and join a valid ZigBee network. See "Managing End
Devices" chapter for details.
Resetting the End Device
When the end device is reset or power cycled, if the orphan scan successfully locates a parent, the end device
then checks its PAN ID, operating channel and stack profile against the network configuration settings (ID, SC,
ZS). It also verifies the saved security policy is valid based on the security configuration commands (EE, KY). If
the end device's PAN ID, operating channel, stack profile, or security policy is invalid, the end device will leave
the network and attempt to join a new network based on its network joining command values.
To prevent the end device from leaving an existing network, the WR command should be issued after all
network joining commands have been configured in order to retain these settings through power cycle or reset
events.
Leaving a Network
There are a couple of mechanisms that will cause the router to leave its current PAN and attempt to discover
and join a new network based on its network joining parameter values. These include the following:
•The ID command changes such that the current 64-bit PAN ID is invalid.
•The SC command changes such that the current operating channel (CH) is not included in the channel
mask.
•The ZS or any of the security command values change.
•The NR0 command is issued to cause the end device to leave.
•The NR1 command is issued to send a broadcast transmission, causing all devices in the network to leave
and migrate to a different channel.
•The commissioning button is pressed 4 times or the CB command is issued with a parameter of 4.
•The end device's parent is powered down or the end device is moved out of range of the parent such that
the end device fails to receive poll acknowledgment messages.
Note that changes to command values only take effect when changes are applied (AC or CN commands).
Example: Joining a Network
After starting a coordinator (that is allowing joins), the following steps will cause an XBee end device to join the
network:
1. Set ID to the desired 64-bit PAN ID, or to 0 to join any PAN.
2. Set SC to the list of channels to scan to find a valid network.
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3. If SC or ID is changed from the default, apply changes (make SC and ID changes take effect)
by issuing the AC or CN command.
4. The Associate LED will start blinking once the end device has joined a PAN.
5. If the Associate LED is not blinking, the AI command can be read to determine the cause of join
failure.
6. Once the end device has joined, the OP and CH commands will indicate the operating 64-bit
PAN ID and channel the end device joined.
7. The MY command will reflect the 16-bit address the router received when it joined.
8. The API Modem Status frame ("Associated") is sent out the UART (API firmware only).
9. The joined end device will attempt to enter low power sleep modes based on its sleep
configuration commands (SM, SP, SN, ST, SO).
Channel Scanning
As mentioned previously, routers and end devices must scan one or more channels to discover a valid network
to join. When a join attempt begins, the XBee sends a beacon request transmission on the lowest channel
specified in the SC (scan channels) command bitmask. If a valid PAN is found on the channel, the XBee will
attempt to join the PAN on that channel. Otherwise, if a valid PAN is not found on the channel, it will attempt
scanning on the next higher channel in the SC command bitmask. The XBee will continue to scan each channel
(from lowest to highest) in the SC bitmask until a valid PAN is found or all channels have been scanned. Once all
channels have been scanned, the next join attempt will start scanning on the lowest channel specified in the SC
command bitmask.
For example, if the SC command is set to 0x400F, the XBee would start scanning on channel 11 (0x0B) and scan
until a valid beacon is found, or until channels 11, 12, 13, 14, and 25 have been scanned (in that order).
Once an XBee router or end device joins a network on a given channel, if the XBee is told to leave (see "Leaving
a Network" section), it will leave the channel it joined on and continue scanning on the next higher channel in
the SC bitmask.
For example, if the SC command is set to 0x400F, and the XBee joins a PAN on channel 12 (0x0C), if the XBee
leaves the channel, it will start scanning on channel 13, followed by channels 14 and 25 if a valid network is not
found. Once all channels have been scanned, the next join attempt will start scanning on the lowest channel
specified in the SC command bitmask.
Managing Multiple ZigBee Networks
In some applications, multiple ZigBee networks may exist in proximity of each other. The application may need
provisions to ensure the XBee joins the desired network. There are a number of features in ZigBee to manage
joining among multiple networks. These include the following:
•PAN ID Filtering
•Preconfigured Security Keys
•Permit Joining
•Application Messaging
PAN ID Filtering
The XBee can be configured with a fixed PAN ID by setting the ID command to a non-zero value. If the PAN ID
is set to a non-zero value, the XBee will only join a network with the same PAN ID.
Preconfigured Security Keys
Similar to PAN ID filtering, this method requires a known security key be installed on a router to ensure it will
join a ZigBee network with the same security key. If the security key (KY command) is set to a non-zero value,
and if security is enabled (EE command), an XBee router or end device will only join a network with the same
security key.
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Permit Joining
The Permit Joining parameter can be disabled in a network to prevent unwanted devices from joining. When a
new device must be added to a network, permit-joining can be enabled for a short time on the desired network.
In the XBee firmware, joining is disabled by setting the NJ command to a value less than 0xFF on all routers and
coordinator devices. Joining can be enabled for a short time using the commissioning push-button (see Network
Commissioning chapter for details) or the CB command.
Application Messaging
If the above mechanisms are not feasible, the application could build in a messaging framework between the
coordinator and devices that join its network. For example, the application code in joining devices could send a
transmission to the coordinator after joining a network, and wait to receive a defined reply message. If the
application does not receive the expected response message after joining, the application could force the XBee
to leave and continue scanning (see NR parameter).
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4. Transmission, Addressing, and Routing
Addressing
All ZigBee devices have two different addresses, a 64-bit and a 16-bit address. The characteristics of each are
described below.
64-bit Device Addresses
The 64-bit address is a unique device address assigned during manufacturing. This address is unique to each
physical device. The 64-bit address includes a 3-byte Organizationally Unique Identifier (OUI) assigned by the
IEEE. The 64-bit address is also called the extended address.
16-bit Device Addresses
A device receives a 16-bit address when it joins a ZigBee network. For this reason, the 16-bit address is also
called the "network address". The 16-bit address of 0x0000 is reserved for the coordinator. All other devices
receive a randomly generated address from the router or coordinator device that allows the join. The 16-bit
address can change under certain conditions:
•An address conflict is detected where two devices are found to have the same 16-bit address
•A device leaves the network and later joins (it can receive a different address)
All ZigBee transmissions are sent using the source and destination 16-bit addresses. The routing tables on
ZigBee devices also use 16-bit addresses to determine how to route data packets through the network.
However, since the 16-bit address is not static, it is not a reliable way to identify a device.
To solve this problem, the 64-bit destination address is often included in data transmissions to guarantee data is
delivered to the correct destination. The ZigBee stack can discover the 16-bit address, if unknown, before
transmitting data to a remote.
Application Layer Addressing
ZigBee devices can support multiple application profiles, cluster IDs, and endpoints. (See "ZigBee Application
Layers - In Depth" in chapter 3.) Application layer addressing allows data transmissions to be addressed to
specific profile IDs, cluster IDs, and endpoints. Application layer addressing is useful if an application must
•Interoperate with other ZigBee devices outside of the Digi application profile
•Utilize service and network management capabilities of the ZDO
•Operate on a public application profile such as Home Controls or Smart Energy.
The API firmware provides a simple yet powerful interface that can easily send data to any profile ID, endpoint,
and cluster ID combination on any device in a ZigBee network.
Data Transmission
ZigBee data packets can be sent as either unicast or broadcast transmissions. Unicast transmissions route data from
one source device to one destination device, whereas broadcast transmissions are sent to many or all devices in the
network.
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Broadcast Transmissions
Broadcast transmissions within the ZigBee protocol are intended to be propagated throughout the entire
network such that all nodes receive the transmission. To accomplish this, the coordinator and all routers that
receive a broadcast transmission will retransmit the packet three times.
Note: when a router or coordinator delivers a broadcast transmission to an end device child, the transmission is
only sent once (immediately after the end device wakes and polls the parent for any new data). See Parent
Operation section in chapter 6 for details.
Broadcast Data Transmission
Legend
C=Coordinator
R=Router
E=End Device
Each node that transmits the broadcast will also create an entry in a local broadcast transmission table. This
entry is used to keep track of each received broadcast packet to ensure the packets are not endlessly
transmitted. Each entry persists for 8 seconds. The broadcast transmission table holds 8 entries.
For each broadcast transmission, the ZigBee stack must reserve buffer space for a copy of the data packet. This
copy is used to retransmit the packet as needed. Large broadcast packets will require more buffer space. This
information on buffer space is provided for general knowledge; the user does not and cannot change any buffer
spacing. Buffer spacing is handled automatically by the XBee module.
Since broadcast transmissions are retransmitted by each device in the network, broadcast messages should be
used sparingly.
Unicast Transmissions
Unicast transmissions are sent from one source device to another destination device. The destination device
could be an immediate neighbor of the source, or it could be several hops away. Unicast transmissions that are
sent along a multiple hop path require some means of establishing a route to the destination device. See the
"RF Packet Routing" section in chapter 4 for details.
Address Resolution
As mentioned previously, each device in a ZigBee network has both a 16-bit (network) address and a 64-bit
(extended) address. The 64-bit address is unique and assigned to the device during manufacturing, and the
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16-bit address is obtained after joining a network. The 16-bit address can also change under certain
conditions.
When sending a unicast transmission, the ZigBee network layer uses the 16-bit address of the destination
and each hop to route the data packet. If the 16-bit address of the destination is not known, the ZigBee
stack includes a discovery provision to automatically discover the destination device's 16-bit address before
routing the data.
To discover a 16-bit address of a remote, the device initiating the discovery sends a broadcast address
discovery transmission. The address discovery broadcast includes the 64-bit address of the remote device
whose 16-bit address is being requested. All nodes that receive this transmission check the 64-bit address
in the payload and compare it to their own 64-bit address. If the addresses match, the device sends a
response packet back to the initiator. This response includes the remote's 16-bit address. When the
discovery response is received, the initiator will then transmit the data.
Address Table
Each ZigBee device maintains an address table that maps a 64-bit address to a 16-bit address. When a
transmission is addressed to a 64-bit address, the ZigBee stack searches the address table for an entry
with a matching 64-bit address, in hopes of determining the destination's 16-bit address. If a known 16-bit
address is not found, the ZigBee stack will perform address discovery to discover the device's current 16bit address.
Sample Address Table
64-bit Address
16-bit Address
0013 A200 4000 0001 0x4414
0013 A200 400A 3568 0x1234
0013 A200 4004 1122
0xC200
0013 A200 4002 1123
0xFFFE (unknown)
The XBee modules can store up to 10 address table entries. For applications where a single device (e.g.
coordinator) may send unicast transmissions to more than 10 devices, the application should implement an
address table to store the 16-bit and 64-bit addresses for each remote device. Any XBee that will send data
to more than 10 remotes should also use API firmware. The application can then send both the 16-bit and
64-bit addresses to the XBee in the API transmit frames which will significantly reduce the number of 16-bit
address discoveries and greatly improve data throughput.
If an application will support an address table, the size should ideally be larger than the maximum number
of destination addresses the device will communicate with. Each entry in the address table should contain a
64-bit destination address and its last known 16-bit address.
When sending a transmission to a destination 64-bit address, the application should search the address
table for a matching 64-bit address. If a match is found, the 16-bit address should be populated into the
16-bit address field of the API frame. If a match is not found, the 16-bit address should be set to 0xFFFE
(unknown) in the API transmit frame.
The API provides indication of a remote device's 16-bit address in the following frames:
•All receive data frames
Rx Data (0x90)
Rx Explicit Data (0x91)
IO Sample Data (0x92)
Node Identification Indicator (0x95)
Route Record Indicator (0xA1)
etc.
•Transmit status frame (0x8B)
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The application should always update the 16-bit address in the address table when one of these frames is
received to ensure the table has the most recently known 16-bit address. If a transmission failure occurs,
the application should set the 16-bit address in the table to 0xFFFE (unknown).
Fragmentation
Each unicast transmission may support up to 84 bytes of RF payload. (Enabling security or using source
routing can reduce this number. See the NP command for details.) However, the XBee ZB firmware supports
a ZigBee feature called fragmentation that allows a single large data packet to be broken up into multiple
RF transmissions and reassembled by the receiver before sending data out its UART. This is shown in the
image below.
The API transmit frame can include up to 255 bytes of data, which will be broken up into multiple
transmissions and reassembled on the receiving side. If one or more of the fragmented messages are not
received by the receiving device, the receiver will drop the entire message, and the sender will indicate a
transmission failure in the Tx Status API frame. ZB firmware can only support one fragmented packet at a
time at the receive node, due to memory constraints.
Applications that do not wish to use fragmentation should avoid sending more than the maximum number
of bytes in a single RF transmission. See the "Maximum RF Payload Size" section for details.
Devices will not receive or reassemble fragmented RF packets if RTS flow control is enabled (D6 command).
Data Transmission Examples
AT Firmware
To send a data packet in AT firmware, the DH and DL commands must be set to match the 64-bit address of
the destination device. DH must match the upper 4-bytes, and DL must match the lower 4 bytes. Since the
coordinator always receives a 16-bit address of 0x0000, a 64-bit address of 0x0000000000000000 is
defined as the coordinator's address (in ZB firmware). The default values of DH and DL are 0x00, which
sends data to the coordinator.
Example 1: Send a transmission to the coordinator.
(In this example, a '\r' refers to a carriage return character.)
A router or end device can send data in two ways. First, set the destination address (DH and DL
commands) to 0x00.
1. Enter command mode ('+++')
2. After receiving an OK\r, issue the following commands:
a. ATDH0\r
b. ATDL0\r
c. ATCN\r
3. Verify that each of the 3 commands returned an OK\r response.
4. After setting these command values, all serial characters will be sent as a unicast transmission
to the coordinator.
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Alternatively, if the coordinator's 64-bit address is known, DH and DL can be set to the coordinator's 64-bit
address. Suppose the coordinator's address is 0x0013A200404A2244.
1. Enter command mode ('+++')
2. After receiving an OK\r, issue the following commands:
a. ATDH13A200\r
b. ATDL404A2244\
c. ATCN\r
3. Verify that each of the 3 commands returned an OK\r response.
4. After setting these command values, all serial characters will be sent as a unicast transmission
to the coordinator.
API Firmware
Use the transmit request, or explicit transmit request frame (0x10 and 0x11 respectively) to send data to
the coordinator. The 64-bit address can either be set to 0x0000000000000000, or to the 64-bit address of
the coordinator. The 16-bit address should be set to 0xFFFE when using the 64-bit address of all 0x00s.
To send an ascii "1" to the coordinator's 0x00 address, the following API frame can be used:
7E 00 0F 10 01 0000 0000 0000 0000 FFFE 00 00 31 C0
If the explicit transmit frame is used, the cluster ID should be set to 0x0011, the profile ID to 0xC105, and
the source and destination endpoints to 0xE8 (recommended defaults for data transmissions in the Digi
profile.) The same transmission could be sent using the following explicit transmit frame:
7E 00 15 11 01 0000 0000 0000 0000 FFFE E8 E8 0011 C105 00 00 31 18
Notice the 16-bit address is set to 0xFFFE. This is required when sending to a 64-bit address of 0x00s.
Now suppose the coordinator's 64-bit address is 0x0013A200404A2244. The following transmit request API
frame (0x10) will send an ASCII "1" to the coordinator:
7E 00 0F 10 01 0013 A200 404A 2244 0000 0000 31 18
Example 2: Send a broadcast transmission.
(In this example, a '\r' refers to a carriage return character.)
Perform the following steps to configure a broadcast transmission:
1. Enter command mode ('+++')
2. After receiving an OK\r, issue the following commands:
a. ATDH0\r
b. ATDLffff\r
c. ATCN\r
3. Verify that each of the 3 commands returned an OK\r response
4. After setting these command values, all serial characters will be sent as a broadcast
transmission.
API Firmware
This example will use the transmit request API frame (0x10) to send an ASCII "1" in a broadcast
transmission.
To send an ascii "1" as a broadcast transmission, the following API frame can be used:
7E 00 0F 10 01 0000 0000 0000 FFFF FFFE 00 00 31 C2
Notice the destination 16-bit address is set to 0xFFFE for broadcast transmissions.
RF Packet Routing
Unicast transmissions may require some type of routing. ZigBee includes several different ways to route data, each
with its own advantages and disadvantages. These are summarized in the table below.
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Routing Approach Description
When to Use
Ad hoc On-demand
Routing paths are created between source and Use in networks that will not scale beyond about
Distance Vector (AODV) destination, possibly traversing multiple nodes 40 destination devices.
Mesh Routing
(“hops”). Each device knows who to send data
to next to eventually reach the destination
Many-to-One Routing
A single broadcast transmission configures
Useful when many remote devices send data to
reverse routes on all devices into the device that a single gateway or collector device.
sends the broadcast
Source Routing
Data packets include the entire route the packet Improves routing efficiency in large networks
should traverse to get from source to
(over 40 remote devices)
destination
Note – End devices do not make use of these routing protocols. Rather, an end device sends a unicast transmission to its
parent and allows the parent to route the data packet in its behalf.
Note - A network cannot revert from Many-to-One routing to AODV routing without first doing a network reset (NR).
Link Status Transmission
Before discussing the various routing protocols, it is worth understanding the primary mechanism in ZigBee for
establishing reliable bi-directional links. This mechanism is especially useful in networks that may have a
mixture of devices with varying output power and/or receiver sensitivity levels.
Each coordinator or router device periodically sends a link status message. This message is sent as a 1-hop
broadcast transmission, received only by one-hop neighbors. The link status message contains a list of
neighboring devices and incoming and outgoing link qualities for each neighbor. Using these messages,
neighboring devices can determine the quality of a bi-directional link with each neighbor and use that
information to select a route that works well in both directions.
For example, consider a network of two neighboring devices that send periodic link status messages. Suppose
that the output power of device A is +18dBm, and the output power of device B is +3dBm (considerably less
than the output power of device A). The link status messages might indicate the following:
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This mechanism enables devices A and B to recognize that the link is not reliable in both directions and select a
different neighbor when establishing routes. (Such links are called asymmetric links, meaning the link quality is
not similar in both directions.)
When a router or coordinator device powers on, it sends link status messages every couple seconds to attempt
to discover link qualities with its neighbors quickly. After being powered on for some time, the link status
messages are sent at a much slower rate (about every 3-4 times per minute).
AODV Mesh Routing
ZigBee employs mesh routing to establish a route between the source device and the destination. Mesh routing
allows data packets to traverse multiple nodes (hops) in a network to route data from a source to a destination.
Routers and coordinators can participate in establishing routes between source and destination devices using a
process called route discovery. The Route discovery process is based on the AODV (Ad-hoc On-demand Distance
Vector routing) protocol.
Sample Transmission Through a Mesh Network
AODV (Ad-hoc On-demand Distance Vector) Routing Algorithm
Routing under the AODV protocol is accomplished using tables in each node that store the next hop
(intermediary node between source and destination nodes) for a destination node. If a next hop is not known,
route discovery must take place in order to find a path. Since only a limited number of routes can be stored on
a Router, route discovery will take place more often on a large network with communication between many
different nodes.
Node
R3
R5
Destination Address
Next Hop Address
Router 6
Coordinator
Router 6
Router 5
Router 6
Router 6
When a source node must discover a route to a destination node, it sends a broadcast route request command.
The route request command contains the source network address, the destination network address and a path
cost field (a metric for measuring route quality). As the route request command is propagated through the
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network (refer to the Broadcast Transmission), each node that re-broadcasts the message updates the path
cost field and creates a temporary entry in its route discovery table.
Sample Route Request (Broadcast) Transmission Where R3 is Trying to Discover a Route to R6
When the destination node receives a route request, it compares the ‘path cost’ field against previously received
route request commands. If the path cost stored in the route request is better than any previously received, the
destination node will transmit a route reply packet to the node that originated the route request. Intermediate
nodes receive and forward the route reply packet to the source node (the node that originated route request).
Sample Route Reply (Unicast) Where R6 Sends a Route Reply to R3.
Note: R6 could send multiple replies if it identifies a better route.
Retries and Acknowledgments
ZigBee includes acknowledgment packets at both the Mac and Application Support (APS) layers. When data is
transmitted to a remote device, it may traverse multiple hops to reach the destination. As data is transmitted
from one node to its neighbor, an acknowledgment packet (Ack) is transmitted in the opposite direction to
indicate that the transmission was successfully received. If the Ack is not received, the transmitting device will
retransmit the data, up to 4 times. This Ack is called the Mac layer acknowledgment.
In addition, the device that originated the transmission expects to receive an acknowledgment packet (Ack)
from the destination device. This Ack will traverse the same path that the data traversed, but in the opposite
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direction. If the originator fails to receive this Ack, it will retransmit the data, up to 2 times until an Ack is
received. This Ack is called the ZigBee APS layer acknowledgment.
Refer to the ZigBee specification for more details.
Many-to-One Routing
In networks where many devices must send data to a central collector or gateway device, AODV mesh routing
requires significant overhead. If every device in the network had to discover a route before it could send data to
the data collector, the network could easily become inundated with broadcast route discovery messages.
Many-to-one routing is an optimization for these kinds of networks. Rather than require each device to do its
own route discovery, a single many-to-one broadcast transmission is sent from the data collector to establish
reverse routes on all devices. This is shown in the figure below. The left side shows the many broadcasts the
devices can send when they create their own routes and the route replies generated by the data collector. The
right side shows the benefits of many-to-one routing where a single broadcast creates reverse routes to the
data collector on all routers.
The many-to-one broadcast is a route request message with the target discovery address set to the address of
the data collector. Devices that receive this route request create a reverse many-to-one routing table entry to
create a path back to the data collector. The ZigBee stack on a device uses historical link quality information
about each neighbor to select a reliable neighbor for the reverse route.
When a device sends data to a data collector, and it finds a many-to-one route in its routing table, it will
transmit the data without performing a route discovery. The many-to-one route request should be sent
periodically to update and refresh the reverse routes in the network.
Applications that require multiple data collectors can also use many-to-one routing. If more than one data
collector device sends a many-to-one broadcast, devices will create one reverse routing table entry for each
collector.
In ZB firmware, the AR command is used to enable many-to-one broadcasting on a device. The AR command
sets a time interval (measured in 10 second units) for sending the many to one broadcast transmission. (See
the command table for details.)
Source Routing
In applications where a device must transmit data to many remotes, AODV routing would require performing
one route discovery for each destination device to establish a route. If there are more destination devices than
there are routing table entries, established AODV routes would be overwritten with new routes, causing route
discoveries to occur more regularly. This could result in larger packet delays and poor network performance.
ZigBee source routing helps solve these problems. In contrast to many-to-one routing that establishes routing
paths from many devices to one data collector, source routing allows the collector to store and specify routes for
many remotes.
To use source routing, a device must use the API firmware, and it must send periodic many-to-one route
request broadcasts (AR command) to create a many-to-one route to it on all devices. When remote devices
send RF data using a many-to-one route, they first send a route record transmission. The route record
transmission is unicast along the many-to-one route until it reaches the data collector. As the route record
traverses the many-to-one route, it appends the 16-bit address of each device in the route into the RF payload.
When the route record reaches the data collector, it contains the address of the sender, and the 16-bit address
of each hop in the route. The data collector can store the routing information and retrieve it later to send a
source routed packet to the remote. This is shown in the images below.
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The data collector sends a
Many-to-One route request
broadcast to create reverse
routes on all devices.
A remote device sends an RF data packet
to the data collector. (This is prefaced by
a route record transmission to the data
collector.)
After obtaining a source route, the data
collector sends a source routed
transmission to the remote device.
Acquiring Source Routes
Acquiring source routes requires the remote devices to send a unicast to a data collector (device that sends
many-to-one route request broadcasts). There are several ways to force remotes to send route record
transmissions.
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1.
If the application on remote devices periodically sends data to the data collector, each
transmission will force a route record to occur.
2.
The data collector can issue a network discovery command (ND command) to force all XBee
devices to send a network discovery response. Each network discovery response will be prefaced by a route
record.
3.
Periodic IO sampling can be enabled on remotes to force them to send data at a regular rate.
Each IO sample would be prefaced by a route record. (See chapter 8 for details.)
4.
If the NI string of the remote device is known, the DN command can be issued with the NI
string of the remote in the payload. The remote device with a matching NI string would send a route record
and a DN response.
Storing Source Routes
When a data collector receives a route record, it sends it out the UART as a Route Record Indicator API
frame (0xA1). To use source routing, the application should receive these frames and store the source
route information.
Sending a Source Routed Transmission
To send a source routed transmission, the application should send a Create Source Route API frame (0x21)
to the XBee to create a source route in its internal source route table. After sending the Create Source
Route API frame, the application can send data transmission or remote command request frames as needed
to the same destination, or any destination in the source route. Once data must be sent to a new
destination (a destination not included in the last source route), the application should first send a new
Create Source Route API frame. The XBee can buffer one source route that includes up to 10 hops
(excluding source and destination).
For example, suppose a network exists with a coordinator and 5 routers (R1, R2, R3, R4, R5) with known
source routes as shown below.
To send a source-routed packet to R3, the application must send a Create Source Route API frame (0x21)
to the XBee, with a destination of R3, and 2 hops (R1 and R2). If the 64- bit address of R3 is 0x0013A200
404a1234 and the 16-bit addresses of R1, R2, and R3 are:
Device 16-bit address
R1
0xAABB
R2
0xCCDD
R3
0xEEFF
Then the Create Source Route API frame would be:
7E 0012 21 00 0013A200 404A1234 EEFF 00 02 CCDD AABB 5C
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Where:
0x0012 - length
0x21 - API ID (create source route)
0x00 - frame ID (set to 0 always)
0x0013A200 404A1234 - 64-bit address of R3 (destination)
0xEEFF - 16-bit address of R3 (destination)
0x00 - Route options (set to 0)
0x02 - Number of intermediate devices in the source route
0xCCDD - Address of furthest device (1-hop from target)
0xAABB - Address of next-closer device
0x5C - Checksum (0xFF - SUM (all bytes after length))
Repairing Source Routes
It is possible in a network to have an existing source route fail (i.e. a device in the route moves or goes
down, etc.). If a device goes down in a source routed network, all routes that used the device will be
broken.
As mentioned previously, source routing must be used with many-to-one routing. (A device that uses
source routing must also send a periodic many-to-one broadcast in order to keep routes fresh). If a source
route is broken, remote devices must send in new route record transmissions to the data collector to
provide it with a new source route. This requires that remote devices periodically send data transmissions
into the data collector. See the earlier "Acquiring Source Routes" section for details.
Retries and Acknowledgments
ZigBee includes acknowledgment packets at both the Mac and Application Support (APS) layers. When data
is transmitted to a remote device, it may traverse multiple hops to reach the destination. As data is
transmitted from one node to its neighbor, an acknowledgment packet (Ack) is transmitted in the opposite
direction to indicate that the transmission was successfully received. If the Ack is not received, the
transmitting device will retransmit the data, up to 4 times. This Ack is called the Mac layer
acknowledgment.
In addition, the device that originated the transmission expects to receive an acknowledgment packet (Ack)
from the destination device. This Ack will traverse the same path that the data traversed, but in the
opposite direction. If the originator fails to receive this Ack, it will retransmit the data, up to 2 times until an
Ack is received. This Ack is called the ZigBee APS layer acknowledgment.
Refer to the ZigBee specification for more details.
Encrypted Transmissions
Encrypted transmissions are routed similar to non-encrypted transmissions with one exception. As an encrypted
packet propagates from one device to another, each device decrypts the packet using the network key, and
authenticates the packet by verifying packet integrity. It then re-encrypts the packet with its own source address
and frame counter values, and sends the message to the next hop. This process adds some overhead latency to
unicast transmissions, but it helps prevent replay attacks. See chapter 5 for details.
Maximum RF Payload Size
XBee ZB firmware includes a command (ATNP) that returns the maximum number of RF payload bytes that can be
sent in a unicast transmission. Querying the NP command, like most other commands, returns a HEXADECIMAL
value. This number will change based on whether security is enabled or not. If security is enabled (EE command),
the maximum number of RF payload bytes decreases since security requires additional overhead.
After reading the NP value, the following conditions can affect the maximum number of data bytes in a single RF
transmission:
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•Broadcast transmissions can support 8 bytes more than unicast transmissions.
•If source routing is used, the 16-bit addresses in the source route are inserted into the RF payload space. For
example, if NP returns 84 bytes, and a source route must traverse 3 intermediate hops (3 16-bit addresses),
the total number of bytes that can be sent in one RF packet is 78.
•Enabling APS encryption (API tx option bit set) will reduce the number of payload bytes by 4.
Throughput
Throughput in a ZigBee network can vary by a number of variables, including: number of hops, encryption enabled/
disabled, sleeping end devices, failures/route discoveries. Our empirical testing showed the following throughput
performance in a robust operating environment (low interference).
Data Throughput*
Configuration
Data Throughput
1 hop, RR, SD
35kbps
1 hop, RR, SE
19kbps
1 hop, RE, SD
25kbps
1 hop, RE, SE
16kbps
1 hop, ER, SD
21kbps
1 hop, ER, SE
16kbps
4 hops, RR, SD 10kbps
4 hops, RR, SE 5kbps
RR = router to router,
RE = router to end device (non-sleeping),
ER = end device (non-sleeping) to router,
SD = security disabled,
SE = security enabled.
4 hops = 5 nodes total, 3 intermediate router nodes
* Data throughput measurements were made setting the serial interface rate to 115200 bps, and measuring the
time to send 100,000 bytes from source to destination. During the test, no route discoveries or failures occurred.
ZDO Transmissions
ZigBee defines a ZigBee Device Objects layer (ZDO) that can provide device and service discovery and network
management capabilities. This layer is described below.
ZigBee Device Objects (ZDO)
The ZigBee Device Objects (ZDO) is supported to some extent on all ZigBee devices. The ZDO is an endpoint
that implements services described in the ZigBee Device Profile in the ZigBee specification. Each service has an
assigned cluster ID, and most service requests have an associated response. The following table describes some
common ZDO services.
Cluster Name Cluster ID Description
© 2011 Digi International, Inc.
Network Address
Request
0x0000
Request a 16-bit address of the
radio with a matching 64-bit
address (required parameter).
Active Endpoints
Request
0x0005
Request a list of endpoints from a
remote device.
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LQI Request
0x0031
Request data from a neighbor table
of a remote device.
Routing Table
Request
0x0032
Request to retrieve routing table
entries from a remote device.
Network Address
Response
0x8000
Response that includes the 16-bit
address of a device.
Cluster Name Cluster ID Description
LQI Response
0x8031
Response that includes neighbor
table data from a remote device.
Routing Table
Response
0x8032
Response that includes routing
table entry data from a remote
device.
Refer to the ZigBee specification for a detailed description of all ZigBee Device Profile services.
Sending a ZDO Command
To send a ZDO command, an explicit transmit API frame must be used and formatted correctly. The source and
destination endpoints must be set to 0, and the profile ID must be set to 0. The cluster ID must be set to match
the cluster ID of the appropriate service. For example, to send an active endpoints request, the cluster ID must
be set to 0x0005.
The first byte of payload in the API frame is an application sequence number (transaction sequence number)
that can be set to any single byte value. This same value will be used in the first byte of the ZDO response. All
remaining payload bytes must be set as required by the ZDO. All multi-byte values must be sent in little endian
byte order.
Receiving ZDO Commands and Responses
In XBee ZB firmware, ZDO commands can easily be sent using the API. In order to receive incoming ZDO
commands, receiver application addressing must be enabled with the AO command. (See examples later in this
section.) Not all incoming ZDO commands are passed up to the application.
When a ZDO message is received on endpoint 0 and profile ID 0, the cluster ID indicates the type of ZDO
message that was received. The first byte of payload is generally a sequence number that corresponds to a
sequence number of a request. The remaining bytes are set as defined by the ZDO. Similar to a ZDO request,
all multi-byte values in the response are in little endian byte order.
Example 1: Send a ZDO LQI Request to read the neighbor table contents of a remote.
Looking at the ZigBee specification, the cluster ID for an LQI Request is 0x0031, and the payload only
requires a single byte (start index). This example will send an LQI request to a remote device with a 64-bit
address of 0x0013A200 40401234. The start index will be set to 0, and the transaction sequence number
will be set to 0x76
API Frame:
7E 0016 11 01 0013A200 40401234 FFFE 00 00 0031 0000 00 00 76 00 CE
0x0016 - length
0x11 - Explicit transmit request
0x01 - frame ID (set to a non-zero value to enable the transmit status message, or set to 0 to disable)
0x0013A200 40401234 - 64-bit address of the remote
0xFFFE - 16-bit address of the remote (0xFFFE = unknown). Optionally, set to the 16-bit address of the
destination if known.
0x00 - Source endpoint
0x00 - Destination endpoint
0x0031 - Cluster ID (LQI Request, or Neighbor table request)
0x0000 - Profile ID (ZigBee Device Profile)
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0x00 - Broadcast radius
0x00 - Tx Options
0x76 - Transaction sequence number
0x00 - Required payload for LQI request command
0xCE - Checksum (0xFF - SUM (all bytes after length))
Description:
This API frame sends a ZDO LQI request (neighbor table request) to a remote device to obtain data from its
neighbor table. Recall that the AO command must be set correctly on an API device to enable the explicit
API receive frames in order to receive the ZDO response.
Example 2: Send a ZDO Network Address Request to discover the 16-bit address of a remote.
Looking at the ZigBee specification, the cluster ID for a network Address Request is 0x0000, and the
payload only requires the following:
[64-bit address] + [Request Type] + [Start Index]
This example will send a Network Address Request as a broadcast transmission to discover the 16-bit
address of the device with a 64-bit address of 0x0013A200 40401234. The request type and start index will
be set to 0, and the transaction sequence number will be set to 0x44
API Frame:
7E 001F 11 01 00000000 0000FFFF FFFE 00 00 0000 0000 00 00 44 34124040 00A21300 00 00 33
0x001F - length
0x11 - Explicit transmit request
0x01 - frame ID (set to a non-zero value to enable the transmit status message, or set to 0 to disable)
0x00000000 0000FFFF - 64-bit address for a broadcast transmission
0xFFFE - Set to this value for a broadcast transmission.
0x00 - Source endpoint
0x00 - Destination endpoint
0x0000 - Cluster ID (Network Address Request)
0x0000 - Profile ID (ZigBee Device Profile)
0x00 - Broadcast radius
0x00 - Tx Options
0x44 - Transaction sequence number
0x34124040 00A21300 00 00 - Required payload for Network Address Request command
0x33 - Checksum (0xFF - SUM (all bytes after length))
Description:
This API frame sends a broadcast ZDO Network Address Request to obtain the 16-bit address of a device
with a 64-bit address of 0x0013A200 40401234. Note the bytes for the 64-bit address were inserted in
little endian byte order. All multi-byte fields in the API payload of a ZDO command must have their data
inserted in little endian byte order. Also recall that the AO command must be set correctly on an API device
to enable the explicit API receive frames in order to receive the ZDO response.
Transmission Timeouts
The ZigBee stack includes two kinds of transmission timeouts, depending on the nature of the destination device.
For destination devices such as routers whose receiver is always on, a unicast timeout is used. The unicast timeout
estimates a timeout based on the number of unicast hops the packet should traverse to get data to the destination
device. For transmissions destined for end devices, the ZigBee stack uses an extended timeout that includes the
unicast timeout (to route data to the end device's parent), and it includes a timeout for the end device to finish
sleeping, wake, and poll the parent for data.
The ZigBee stack includes some provisions for a device to detect if the destination is an end device or not. The
ZigBee stack uses the unicast timeout unless it knows the destination is an end device.
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The XBee API includes a transmit options bit that can be set to specify if the extended timeout should be used for a
given transmission. If this bit is set, the extended timeout will be used when sending RF data to the specified
destination. To improve routing reliability, applications should set the extended timeout bit when sending data to end
devices if:
•The application sends data to 10 or more remote devices, some of which are end devices, AND
•The end devices may sleep longer than the unicast timeout
Equations for these timeouts are computed in the following sections.
Note: The timeouts in this section are worst-case timeouts and should be padded by a few hundred milliseconds.
These worst-case timeouts apply when an existing route breaks down (e.g. intermediate hop or destination device
moved).
Unicast Timeout
The unicast timeout is settable with the NH command. The actual unicast timeout is computed as ((50 * NH) +
100). The default NH value is 30 which equates to a 1.6 second timeout.
The unicast timeout includes 3 transmission attempts (1 attempt and 2 retries). The maximum total timeout is
about:
3 * ((50 * NH) + 100).
For example, if NH=30 (0x1E), the unicast timeout is about
3 * ((50 * 30) + 100), or
3 * (1500 + 100), or
3 * (1600), or
4800 ms, or
4.8 seconds.
Extended Timeout
The worst-case transmission timeout when sending data to an end device is somewhat larger than when
transmitting to a router or coordinator. As described later in chapter 6, RF data packets are actually sent to the
parent of the end device, who buffers the packet until the end device wakes to receive it. The parent will buffer
an RF data packet for up to (1.2 * SP) time.
To ensure the end device has adequate time to wake and receive the data, the extended transmission timeout
to an end device is:
(50 * NH) + (1.2 * SP)
This timeout includes the packet buffering timeout (1.2 * SP) and time to account for routing through the mesh
network (50 * NH).
If an acknowledgment is not received within this time, the sender will resend the transmission up to two more
times. With retries included, the longest transmission timeout when sending data to an end device is:
3 * ((50 * NH) + (1.2 * SP))
The SP value in both equations must be entered in millisecond units. (The SP command setting uses 10ms units
and must be converted to milliseconds to be used in this equation.)
For example, suppose a router is configured with NH=30 (0x1E) and SP=0x3E8 (10,000 ms), and that it is
either trying to send data to one of its end device children, or to a remote end device. The total extended
timeout to the end device is about:
3 * ((50 * NH) + (1.2 * SP)), or
3 * (1500 + 12000), or
3 * (13500), or
40500 ms, or
40.5 seconds.
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Transmission Examples
Example 1: Send a unicast API data transmission to the coordinator using 64-bit address 0, with
payload "TxData".
API Frame:
7E 0014 10 01 00000000 00000000 FFFE 00 00 54 78 44 61 74 61
AB
Field Composition:
0x0014 - length
0x10 - API ID (tx data)
0x01 - frame ID (set greater than 0 to enable the tx-status response)
0x00000000 00000000 - 64-bit address of coordinator (ZB definition)
0xFFFE - Required 16-bit address if sending data to 64-bit address of 0.
0x00 - Broadcast radius (0 = max hops)
0x00 - Tx options
0x54 78 44 61 74 61 - ASCII representation of "TxData" string
0xAB - Checksum (0xFF - SUM (all bytes after length))
Description:
This transmission sends the string "TxData" to the coordinator, without knowing the coordinator device's 64-bit
address. A 64-bit address of 0 is defined as the coordinator in ZB firmware. If the coordinator's 64-bit address
was known, the 64-bit address of 0 could be replaced with the coordinator's 64-bit address, and the 16-bit
address could be set to 0.
Example 2 - Send a broadcast API data transmission that all devices can receive (including sleeping
end devices), with payload "TxData".
API Frame:
7E 0014 10 01 00000000 0000FFFF FFFE 00 00 54 78 44 61 74 61
AD
Field Composition:
0x0014 - length
0x10 - API ID (tx data)
0x01 - frame ID (set to a non-zero value to enable the tx-status response)
0x00000000 0000FFFF - Broadcast definition (including sleeping end devices
0xFFFE - Required 16-bit address to send broadcast transmission.
0x00 - Broadcast radius (0 = max hops)
0x00 - Tx options
0x54 78 44 61 74 61 - ASCII representation of "TxData" string
0xAD - Checksum (0xFF - SUM (all bytes after length))
Description:
This transmission sends the string "TxData" as a broadcast transmission. Since the destination address is set to
0xFFFF, all devices, including sleeping end devices can receive this broadcast.
If receiver application addressing is enabled, the XBee will report all received data frames in the explicit format
(0x91) to indicate the source and destination endpoints, cluster ID, and profile ID that each packet was received
on. (Status messages like modem status and route record indicators are not affected.)
To enable receiver application addressing, set the AO command to 1 using the AT command frame (0x08).
Here's how to do this:
API Frame:
7E 0005 08 01 414F 01 65
Field Composition:
0x0005 - length
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0x08 - API ID (at command)
0x01 - frame ID (set to a non-zero value to enable AT command response frames)
0x414F - ASCII representation of 'A','O' (the command being issued)
0x01 - Parameter value
0x65 - Checksum (0xFF - SUM (all bytes after length))
Description:
Setting AO=1 is required for the XBee to use the explicit receive API frame (0x91) when RF data packets are
received. This is required if the application needs indication of source or destination endpoint, cluster ID, and/
or profile ID values used in received ZigBee data packets. ZDO messages can only be received if AO=1.
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5. Security
ZigBee supports various levels of security that can be configured depending on the needs of the application. Security
provisions include:
•128-bit AES encryption
•Two security keys that can be preconfigured or obtained during joining
•Support for a trust center
•Provisions to ensure message integrity, confidentiality, and authentication.
The first half of this chapter describes various security features defined in the ZigBee-PRO specification, while the last
half illustrates how the XBee and XBee-PRO modules can be configured to support these features
Security Modes
The ZigBee standard supports three security modes – residential, standard, and high security. Residential security
was first supported in the ZigBee 2006 standard. This level of security requires a network key be shared among
devices. Standard security adds a number of optional security enhancements over residential security, including an
APS layer link key. High security adds entity authentication, and a number of other features not widely supported.
XBee ZB modules primarily support standard security, although end devices that support residential security can join
and interoperate with standard security devices. The remainder of this chapter focuses on material that is relevant
to standard security.
ZigBee Security Model
ZigBee security is applied to the Network and APS layers. Packets are encrypted with 128-bit AES encryption. A
network key and optional link key can be used to encrypt data. Only devices with the same keys are able to
communicate together in a network. Routers and end devices that will communicate on a secure network must
obtain the correct security keys.
Network Layer Security
The network key is used to encrypt the APS layer and application data. In addition to encrypting application
messages, network security is also applied to route request and reply messages, APS commands, and ZDO
commands. Network encryption is not applied to MAC layer transmissions such as beacon transmissions, etc. If
security is enabled in a network, all data packets will be encrypted with the network key.
Packets are encrypted and authenticated using 128-bit AES. This is shown in the figure below.
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Frame Counter
The network header of encrypted packets includes a 32-bit frame counter. Each device in the network maintains
a 32-bit frame counter that is incremented for every transmission. In addition, devices track the last known 32bit frame counter for each of its neighbors. If a device receives a packet from a neighbor with a smaller frame
counter than it has previously seen, the packet is discarded. The frame counter is used to protect against replay
attacks.
If the frame counter reaches a maximum value of 0xFFFFFFFF, it does not wrap to 0 and no more transmissions
can be sent. Due to the size of the frame counters, reaching the maximum value is a very unlikely event for
most applications. The following table shows the required time under different conditions, for the frame counter
to reach its maximum value.
Average Transmission Rate Time until 32-bit frame counter expires
1 / second
136 years
10 / second
13.6 years
To clear the frame counters without compromising security, the network key can be changed in the network.
When the network key is updated, the frame counters on all devices reset to 0. (See the Network Key Updates
section for details.)
Message Integrity Code
The network header, APS header, and application data are all authenticated with 128-bit AES. A hash is
performed on these fields and is appended as a 4-byte message integrity code (MIC) to the end of the packet.
The MIC allows receiving devices to ensure the message has not been changed. The MIC provides message
integrity in the ZigBee security model. If a device receives a packet and the MIC does not match the device’s
own hash of the data, the packet is dropped.
Network Layer Encryption and Decryption
Packets with network layer encryption are encrypted and decrypted by each hop in a route. When a device
receives a packet with network encryption, it decrypts the packet and authenticates the packet. If the device is
not the destination, it then encrypts and authenticates the packet, using its own frame counter and source
address in the network header section.
Since network encryption is performed at each hop, packet latency is slightly longer in an encrypted network
than in a non-encrypted network. Also, security requires 18 bytes of overhead to include a 32-bit frame counter,
an 8-byte source address, 4-byte MIC, and 2 other bytes. This reduces the number of payload bytes that can be
sent in a data packet.
Network Key Updates
ZigBee supports a mechanism for changing the network key in a network. When the network key is changed,
the frame counters in all devices reset to 0.
APS Layer Security
APS layer security can be used to encrypt application data using a key that is shared between source and
destination devices. Where network layer security is applied to all data transmissions and is decrypted and reencrypted on a hop-by-hop basis, APS security is optional and provides end-to-end security using an APS link
key that only the source and destination device know. APS security can be applied on a packet-by-packet basis.
APS security cannot be applied to broadcast transmissions.
If APS security is enabled, packets are encrypted and authenticated using 128-bit AES. This is shown in the
figure below:
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Message integrity Code
If APS security is enabled, the APS header and data payload are authenticated with 128-bit AES. A hash is
performed on these fields and appended as a 4-byte message integrity code (MIC) to the end of the packet.
This MIC is different than the MIC appended by the network layer. The MIC allows the destination device to
ensure the message has not been changed. If the destination device receives a packet and the MIC does not
match the destination device’s own hash of the data, the packet is dropped.
APS Link Keys
There are two kinds of APS link keys – trust center link keys and application link keys. A trust center link key is
established between a device and the trust center, where an application link key is established between a device
and another device in the network where neither device is the trust center.
APS Layer Encryption and Decryption
Packets with APS layer encryption are encrypted at the source and only decrypted by the destination. Since APS
encryption requires a 5-byte header and a 4-byte MIC, the maximum data payload is reduced by 9 bytes when
APS encryption is used.
Network and APS Layer Encryption
Network and APS layer encryption can both be applied to data. The following figure demonstrates the
authentication and encryption performed on the final ZigBee packet when both are applied.
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Trust Center
ZigBee defines a trust center device that is responsible for authenticating devices that join the network. The
trust center also manages link key distribution in the network.
Forming and Joining a Secure Network
The coordinator is responsible for selecting a network encryption key. This key can either be preconfigured or
randomly selected. In addition, the coordinator generally operates as a trust center and must therefore select
the trust center link key. The trust center link key can also be preconfigured or randomly selected.
Devices that join the network must obtain the network key when they join. When a device joins a secure
network, the network and link keys can be sent to the joining device. If the joining device has a pre-configured
trust center link key, the network key will be sent to the joining device encrypted by the link key. Otherwise, if
the joining device is not pre-configured with the link key, the device could only join the network if the network
key is sent unencrypted (“in the clear”). The trust center must decide whether or not to send the network key
unencrypted to joining devices that are not pre-configured with the link key. Sending the network key
unencrypted is not recommended as it can open a security hole in the network. To maximize security, devices
should be pre-configured with the correct link key.
Implementing Security on the XBee
If security is enabled in the XBee ZB firmware, devices acquire the network key when they join a network. Data
transmissions are always encrypted with the network key, and can optionally be end-to-end encrypted with the APS
link key. The following sections discuss the security settings and options in the XBee ZB firmware.
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Enabling Security
To enable security on a device, the EE command must be set to 1. If the EE command value is changed and
changes are applied (e.g. AC command), the XBee module will leave the network (PAN ID and channel) it was
operating on, and attempt to form or join a new network.
If EE is set to 1, all data transmissions will be encrypted with the network key. When security is enabled, the
maximum number of bytes in a single RF transmission will be reduced. See the NP command for details.
Note: The EE command must be set the same on all devices in a network. Changes to the EE command should
be written to non-volatile memory (to be preserved through power cycle or reset events) using the WR
command.
Setting the Network Security Key
The coordinator must select the network security key for the network. The NK command (write-only) is used to
set the network key. If NK=0 (default), a random network key will be selected. (This should suffice for most
applications.) Otherwise, if NK is set to a non-zero value, the network security key will use the value specified
by NK. NK is only supported on the coordinator.
Routers and end devices with security enabled (ATEE=1) acquire the network key when they join a network.
They will receive the network key encrypted with the link key if they share a pre-configured link key with the
coordinator. See the following section for details.
Setting the APS Trust Center Link Key
The coordinator must also select the trust center link key, using the KY command. If KY=0 (default), the
coordinator will select a random trust center link key (not recommended). Otherwise, if KY is set greater than 0,
this value will be used as the pre-configured trust center link key. KY is write-only and cannot be read.
Note: Application link keys (sent between two devices where neither device is the coordinator) are not
supported in ZB firmware at this time.
Random Trust Center Link Keys
If the coordinator selects a random trust center link key (KY=0, default), then it will allow devices to join
the network without having a pre-configured link key. However, this will cause the network key to be sent
unencrypted over-the-air to joining devices and is not recommended.
Pre-configured Trust Center Link Keys
If the coordinator uses a pre-configured link key (KY > 0), then the coordinator will not send the network
key unencrypted to joining devices. Only devices with the correct pre-configured link key will be able to join
and communicate on the network.
Enabling APS Encryption
APS encryption is an optional layer of security that uses the link key to encrypt the data payload. Unlike network
encryption that is decrypted and encrypted on a hop-by-hop basis, APS encryption is only decrypted by the
destination device. The XBee must be configured with security enabled (EE set to 1) to use APS encryption.
APS encryption can be enabled in API firmware on a per-packet basis. To enable APS encryption for a given
transmission, the "enable APS encryption" transmit options bit should be set in the API transmit frame. Enabling
APS encryption decreases the maximum payload size by 9 bytes.
Using a Trust Center
The EO command can be used to define the coordinator as a trust center. If the coordinator is a trust center, it
will be alerted to all new join attempts in the network. The trust center also has the ability to update or change
the network key on the network.
In ZB firmware, a secure network can be established with or without a trust center. Network and APS layer
encryption are supported if a trust center is used or not.
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Updating the Network Key with a Trust Center
If the trust center has started a network and the NK value is changed, the coordinator will update the
network key on all devices in the network. (Changes to NK will not force the device to leave the network.)
The network will continue to operate on the same channel and PAN ID, but the devices in the network will
update their network key, increment their network key sequence number, and restore their frame counters
to 0.
Updating the Network Key without a Trust Center
If the coordinator is not running as a trust center, the network reset command (NR1) can be used to force
all devices in the network to leave the current network and rejoin the network on another channel. When
devices leave and reform then network, the frame counters are reset to 0. This approach will cause the
coordinator to form a new network that the remaining devices should join. Resetting the network in this
manner will bring the coordinator and routers in the network down for about 10 seconds, and will likely
cause the 16-bit PAN ID and 16-bit addresses of the devices to change.
XBee Security Examples
This section covers some sample XBee configurations to support different security modes. Several AT commands are
listed with suggested parameter values. The notation in this section includes an '=' sign to indicate what each
command register should be set to - for example, EE=1. This is not the correct notation for setting command values
in the XBee. In AT command mode, each command is issued with a leading 'AT' and no '=' sign - for example ATEE1.
In the API, the two byte command is used in the command field, and parameters are populated as binary values in
the parameter field.
Example 1: Forming a network with security (pre-configured link keys)
1. Start a coordinator with the following settings:
a. ID=2234 (arbitrarily selected)
b. EE=1
c. NK=0
d. KY=4455
e. WR (save networking parameters to preserve them through power cycle)
2. Configure one or more routers or end devices with the following settings:
a. ID=2234
b. EE=1
c. KY=4455
d. WR (save networking parameters to preserve them through power cycle)
3. Read the AI setting on the coordinator and joining devices until they return 0 (formed or joined 
a network).
In this example, EE, ID, and KY are set the same on all devices. After successfully joining the secure network,
all application data transmissions will be encrypted by the network key. Since NK was set to 0 on the
coordinator, a random network key was selected. And since the link key (KY) was configured the same on all
devices, to a non-zero value, the network key was sent encrypted by the pre-configured link key (KY) when the
devices joined.
Example 2: Forming a network with security (obtaining keys during joining)
1. Start a coordinator with the following settings:
a. ID=2235
b. EE=1
c. NK=0
d. KY=0
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e. WR (save networking parameters to preserve them through power cycle)
2. Configure one or more routers or end devices with the following settings:
a. ID=2235
b. EE=1
c. KY=0
d. WR (save networking parameters to preserve them through power cycle)
3. Read the AI setting on the coordinator and joining devices until they return 0 (formed or joined
a network).
In this example, EE, ID, and KY are set the same on all devices. Since NK was set to 0 on the coordinator, a
random network key was selected. And since KY was set to 0 on all devices, the network key was sent
unencrypted ("in the clear") when the devices joined. This approach introduces a security vulnerability into the
network and is not recommended.
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6. Network Commissioning and Diagnostics
Network commissioning is the process whereby devices in a mesh network are discovered and configured for operation.
The XBee modules include several features to support device discovery and configuration. In addition to configuring
devices, a strategy must be developed to place devices to ensure reliable routes.
To accommodate these requirements, the XBee modules include various features to aid in device placement,
configuration, and network diagnostics.
Device Configuration
XBee/XBee-PRO ZB modules can be configured locally through serial commands (AT or API), or remotely through
remote API commands. API devices can send configuration commands to set or read the configuration settings of
any device in the network.
Device Placement
For a mesh network installation to be successful, the installer must be able to determine where to place individual
XBee devices to establish reliable links throughout the mesh network.
Link Testing
A good way to measure the performance of a mesh network is to send unicast data through the network from
one device to another to determine the success rate of many transmissions. To simplify link testing, the
modules support a loopback cluster ID (0x12) on the data endpoint (0xE8). Any data sent to this cluster ID on
the data endpoint will be transmitted back to the sender. This is shown in the figure below:
The configuration steps to send data to the loopback cluster ID depend on the firmware type.
AT Firmware
To send data to the loopback cluster ID on the data endpoint of a remote device, set the CI command value to
0x12. The SE and DE commands should be set to 0xE8 (default value). The DH and DL commands should be set
to the address of the remote (0 for the coordinator, or the 64-bit address of the remote). After exiting command
mode, any received serial characters will be transmitted to the remote device, and returned to the sender.
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API Firmware
Send an Explicit Addressing ZigBee Command API frame (0x11) using 0x12 as the cluster ID and 0xE8 as the
source and destination endpoint. Data packets received by the remote will be echoed back to the sender.
RSSI Indicators
It is possible to measure the received signal strength on a device using the DB command. DB returns the RSSI
value (measured in –dBm) of the last received packet. However, this number can be misleading. The DB value
only indicates the received signal strength of the last hop. If a transmission spans multiple hops, the DB value
provides no indication of the overall transmission path, or the quality of the worst link – it only indicates the
quality of the last link and should be used sparingly.
The DB value can be determined in hardware using the RSSI/PWM module pin (pin 6). If the RSSI PWM
functionality is enabled (P0 command), when the module receives data, the RSSI PWM is set to a value based
on the RSSI of the received packet. (Again, this value only indicates the quality of the last hop.) This pin could
potentially be connected to an LED to indicate if the link is stable or not.
Device Discovery
Network Discovery
The network discovery command can be used to discover all Digi modules that have joined a network. Issuing
the ND command sends a broadcast node discovery command throughout the network. All devices that receive
the command will send a response that includes the device’s addressing information, node identifier string (see
NI command), and other relevant information. This command is useful for generating a list of all module
addresses in a network.
When a device receives the node discovery command, it waits a random time before sending its own response.
The maximum time delay is set on the ND sender with the NT command. The ND originator includes its NT
setting in the transmission to provide a delay window for all devices in the network. Large networks may need
to increase NT to improve network discovery reliability. The default NT value is 0x3C (6 seconds).
ZDO Discovery
The ZigBee Device Profile includes provisions to discover devices in a network that are supported on all ZigBee
devices (including non-Digi products). These include the LQI Request (cluster ID 0x0031) and the Network
Update Request (cluster ID 0x0038). The LQI Request can be used to read the devices in the neighbor table of
a remote device, and the Network Update Request can be used to have a remote device do an active scan to
discover all nearby ZigBee devices. Both of these ZDO commands can be sent using the XBee Explicit API
transmit frame (0x11). See the API chapter for details. Refer to the ZigBee specification for formatting details of
these two ZDO frames.
Joining Announce
All ZigBee devices send a ZDO Device Announce broadcast transmission when they join a ZigBee network (ZDO
cluster ID 0x0013). These frames will be sent out the XBee's UART as an Explicit Rx Indicator API frame (0x91)
if AO is set to 1. The device announce payload includes the following information:
[ Sequence Number] + [16-bit address] + [64-bit address] + [Capability]
The 16-bit and 64-bit addresses are received in little-endian byte order (LSB first). See the ZigBee specification
for details.
Commissioning Pushbutton and Associate LED
The XBee modules support a set of commissioning and LED behaviors to aid in device deployment and
commissioning. These include the commissioning pushbutton definitions and associate LED behaviors. These
features can be supported in hardware as shown below.
Commissioning Pushbutton and Associate LED Functionalities
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Push button
20
XBee
15
Associate
LED
A pushbutton and an LED can be connected to module pins 20 and 15 respectively to
support the commissioning pushbutton and associate LED functionalities.
Commissioning Pushbutton
The commissioning pushbutton definitions provide a variety of simple functions to aid in deploying devices in a
network. The commissioning button functionality on pin 20 is enabled by setting the D0 command to 1 (enabled
by default).
Button
Presses
If module is joined to a network
If module is not joined to a network
• Wakes an end device for
30 seconds
• Wakes an end device for
30 seconds
• Sends a node identification broadcast transmission
• Blinks a numeric error
code on the Associate pin
indicating the cause of
join failure (see section
6.4.2).
• Sends a broadcast transmission to enable joining
on the coordinator and all
devices in the network for
1 minute. (If joining is
permanently enabled on a
device (NJ = 0xFF), this
action has no effect on
that device.)
• N/A
• Causes the device to leave
the PAN.
• Issues ATRE to restore
module parameters to
default values, including
ID and SC.
• Issues ATRE to restore
module parameters to
default values, including
ID and SC.
• The device attempts to
join a network based on
its ID and SC settings.
• The device attempts to
join a network based on
its ID and SC settings.
Button presses may be simulated in software using the ATCB command. ATCB should be issued with a
parameter set to the number of button presses to execute. (e.g. sending ATCB1 will execute the action(s)
associated with a single button press.)
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The node identification frame is similar to the node discovery response frame – it contains the device’s address,
node identifier string (NI command), and other relevant data. All API devices that receive the node identification
frame send it out their UART as an API Node Identification Indicator frame (0x95).
Associate LED
The Associate pin (pin 15) can provide indication of the device’s network status and diagnostics information. To
take advantage of these indications, an LED can be connected to the Associate pin as shown in the figure above.
The Associate LED functionality is enabled by setting the D5 command to 1 (enabled by default). If enabled, the
Associate pin is configured as an output and will behave as described in the following sections.
Joined Indication
The Associate pin indicates the network status of a device. If the module is not joined to a network, the
Associate pin is set high. Once the module successfully joins a network, the Associate pin blinks at a regular
time interval. This is shown in the following figure.
Joined Status of a Device
Associate
Device Not Joined
∆t
Device has joined a network
The associate pin can indicate the joined status of a device . Once the device has joined a
network, the associate pin toggles state at a regular interval (∆t). The time can be set by
using the LT command.
The LT command defines the blink time of the Associate pin. If set to 0, the device uses the default blink time
(500ms for coordinator, 250ms for routers and end devices).
Diagnostics Support
The Associate pin works with the commissioning pushbutton to provide additional diagnostics behaviors to aid in
deploying and testing a network. If the commissioning push button is pressed once, and the device has not
joined a network, the Associate pin blinks a numeric error code to indicate the cause of join failure. The number
of blinks is equal to (AI value – 0x20). For example, if AI=0x22, 2 blinks occur.
If the commissioning push button is pressed once, and the device has joined a network, the device transmits a
broadcast node identification packet. If the Associate LED functionality is enabled (D5 command), a device that
receives this transmission will blink its Associate pin rapidly for 1 second.
The following figures demonstrate these behaviors.
AI = 0x22
Associate
(D5 = 1
Device not joined)
AD0/DIO0
A single comm issioning button press when the device has not joined a network that
causes the associate pin to blink to indicate the AI Code where : AI = # blinks + 0x20.
In this example, AI = 0x22.
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Broadcast Node Identification Transmission
Associate Pin
(D5 = 1)
AD0/DIO0 Pin
(Remote Device)
A single button press on a remote device causes a broadcast node identification transmission
to be sent. All devices that receive this transmission blink their associate pin rapidly for one
second if the associate LED functionality is enabled. (D5 = 1)
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7. Managing End Devices
ZigBee end devices are intended to be battery-powered devices capable of sleeping for extended periods of time. Since
end devices may not be awake to receive RF data at a given time, routers and coordinators are equipped with additional
capabilities (including packet buffering and extended transmission timeouts) to ensure reliable data delivery to end
devices.
End Device Operation
When an end device joins a ZigBee network, it must find a router or coordinator device that is allowing end devices
to join. Once the end device joins a network, a parent-child relationship is formed between the end device and the
router or coordinator that allowed it to join. See chapter 3 for details.
When the end device is awake, it sends poll request messages to its parent. When the parent receives a poll request,
it checks a packet queue to see if it has any buffered messages for the end device. It then sends a MAC layer
acknowledgment back to the end device that indicates if it has data to send to the end device or not.
If the end device receives the acknowledgment and finds that the parent has no data for it, the end device can
return to idle mode or sleep. Otherwise, it will remain awake to receive the data. This polling mechanism allows the
end device to enter idle mode and turn its receiver off when RF data is not expected in order to reduce current
consumption and conserve battery life.
The end device can only send data directly to its parent. If an end device must send a broadcast or a unicast
transmission to other devices in the network, it sends the message directly to its parent and the parent performs
any necessary route or address discoveries to route the packet to the final destination.
Parent Operation
Each router or coordinator maintains a child table that contains the addresses of its end device children. A router or
coordinator that has unused entries in its child table is said to have end device capacity, or the ability to allow new
end devices to join. If the child table is completely filled (such that the number of its end device children matches
the number of child table entries), the device cannot allow any more end devices to join to it.
Since the end device children are not guaranteed to be awake at a given time, the parent is responsible for
managing incoming data packets in behalf of its end device children. If a parent receives an RF data transmission
destined for one of its end device children, and if the parent has enough unused buffer space, it will buffer the
packet. The data packet will remain buffered until a timeout expires, or until the end device sends a poll request to
retrieve the data.
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The parent can buffer one broadcast transmission for all of its end device children. When a broadcast transmission is
received and buffered, the parent sets a flag in its child table when each child polls and retrieves the packet. Once all
children have received the broadcast packet, the buffered broadcast packet is discarded. If all children have not
received a buffered broadcast packet and a new broadcast is received, the old broadcast packet is discarded, the
child table flags are cleared, and the new broadcast packet is buffered for the end device children. This is
demonstrated in the figure below.
When an end device sends data to its parent that is destined for a remote device in the network, the parent buffers
the data packet until it can establish a route to the destination. The parent may perform a route or 16-bit address
discovery in behalf of its end device children. Once a route is established, the parent sends the data transmission to
the remote device.
End Device Poll Timeouts
To better support mobile end devices (end devices that can move around in a network), parent router and
coordinator devices have a poll timeout for each end device child. If an end device does not send a poll request
to its parent within the poll timeout, the parent will remove the end device from its child table. This allows the
child table on a router or coordinator to better accommodate mobile end devices in the network.
Packet Buffer Usage
Packet buffer usage on a router or coordinator varies depending on the application. The following activities can
require use of packet buffers for up to several seconds:
•Route and address discoveries
•Application broadcast transmissions
•Stack broadcasts (e.g. ZDO "Device Announce" messages when devices join a network)
•Unicast transmissions (buffered until acknowledgment is received from destination or retries exhausted)
•Unicast messages waiting for end device to wake.
Applications that use regular broadcasting or that require regular address or route discoveries will use up a
significant number of buffers, reducing the buffer availability for managing packets for end device children.
Applications should reduce the number of required application broadcasts, and consider implementing an
external address table or many-to-one and source routing if necessary to improve routing efficiency.
Non-Parent Device Operation
Devices in the ZigBee network treat data transmissions to end devices differently than transmissions to other
routers and coordinators. Recall that when a unicast transmission is sent, if a network acknowledgment is not
received within a timeout, the device resends the transmission. When transmitting data to remote coordinator or
router devices, the transmission timeout is relatively short since these devices are powered and responsive.
However, since end devices may sleep for some time, unicast transmissions to end devices use an extended timeout
mechanism in order to allow enough time for the end device to wake and receive the data transmission from its
parent.
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If a non-parent device does not know the destination is an end device, it will use the standard unicast timeout for
the transmission. However, provisions exist in the Ember ZigBee stack for the parent to inform the message sender
that the destination is an end device. Once the sender discovers the destination device is an end device, future
transmissions will use the extended timeout. See the XBee Router / Coordinator Configuration section in this chapter
for details.
XBee End Device Configuration
XBee end devices support two different sleep modes:
•Pin Sleep
•Cyclic Sleep.
Pin sleep allows an external microcontroller to determine when the XBee should sleep and when it should wake by
controlling the Sleep_RQ pin. In contrast, cyclic sleep allows the sleep period and wake times to be configured
through the use of AT commands. The sleep mode is configurable with the SM command.
In both pin and cyclic sleep modes, XBee end devices poll their parent every 100ms while they are awake to retrieve
buffered data. When a poll request has been sent, the end device enables the receiver until an acknowledgment is
received from the parent. (It generally takes less than 10ms from the time the poll request is sent until the
acknowledgment is received.) The acknowledgment indicates if the parent has buffered data for the end device child
or not. If the acknowledgment indicates the parent has pending data, the end device will leave the receiver on to
receive the data. Otherwise, the end device will turn off the receiver and enter idle mode (until the next poll request
is sent) to reduce current consumption (and improve battery life).
Once the module enters sleep mode, the On/Sleep pin (pin 13) is de-asserted (low) to indicate the module is
entering sleep mode. If CTS hardware flow control is enabled (D7 command), the CTS pin (pin 12) is de-asserted
(high) when entering sleep to indicate that serial data should not be sent to the module. The module will not
respond to serial or RF data when it is sleeping. Applications that must communicate serially to sleeping end devices
are encouraged to observe CTS flow control.
When the XBee wakes from sleep, the On/Sleep pin is asserted (high), and if flow control is enabled, the CTS pin is
also asserted (low). If the module has not joined a network, it will scan all SC channels after waking to try and find
a valid network to join.
Pin Sleep
Pin sleep allows the module to sleep and wake according to the state of the Sleep_RQ pin (pin 9). Pin sleep
mode is enabled by setting the SM command to 1.
When Sleep_RQ is asserted (high), the module will finish any transmit or receive operations and enter a low
power state. For example, if the module has not joined a network and Sleep_RQ is asserted (high), the module
will sleep once the current join attempt completes (i.e. when scanning for a valid network completes). The
module will wake from pin sleep when the Sleep_RQ pin is de-asserted (low).
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In the figure above, t1, t2, and t3 represent the following events:
•T1 - Time when Sleep_RQ is asserted (high)
•T2 - Time when the XBee enters sleep (CTS state change only if hardware flow control is enabled)
•T3 - Time when Sleep_RQ is de-asserted (low) and the module wakes.
The time between T1 and T2 varies depending on the state of the module. In the worst case scenario, if the end
device is trying to join a network, or if it is waiting for an acknowledgment from a data transmission, the delay
could be up to a few seconds.
When the XBee is awake and is joined to a network, it sends a poll request to its parent to see if the parent has
any buffered data for it. The end device will continue to send poll requests every 100ms while it is awake.
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Demonstration of Pin Sleep
Parent and remote devices must be configured to buffer data correctly and to utilize adequate transmission
timeouts. See the XBee Router / Coordinator Configuration section in this chapter for details.
Cyclic Sleep
Cyclic sleep allows the module to sleep for a specified time and wake for a short time to poll its parent for any
buffered data messages before returning to sleep again. Cyclic sleep mode is enabled by setting the SM
command to 4 or 5. SM5 is a slight variation of SM4 that allows the module to be woken prematurely by
asserting the Sleep_RQ pin (pin 9). In SM5, the XBee can wake after the sleep period expires, or if a high-tolow transition occurs on the Sleep_RQ pin. Setting SM to 4 disables the pin wake option.
In cyclic sleep, the module sleeps for a specified time, and then wakes and sends a poll request to its parent to
discover if the parent has any pending data for the end device. If the parent has buffered data for the end
device, or if serial data is received, the XBee will remain awake for a time. Otherwise, it will enter sleep mode
immediately.
The On/Sleep line is asserted (high) when the module wakes, and is de-asserted (low) when the module sleeps.
If hardware flow control is enabled (D7 command), the CTS pin will assert (low) when the module wakes and
can receive serial data, and de-assert (high) when the module sleeps.
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In the figure above, t1, t2, and t3 represent the following events:
•T1 - Time when the module wakes from cyclic sleep
•T2 - Time when the module returns to sleep
•T3 - Later time when the module wakes from cyclic sleep.
The wake time and sleep time are configurable with software commands as described in the sections below.
Wake Time (Until Sleep)
In cyclic sleep mode (SM=4 or 5), if serial or RF data is received, the module will start a sleep timer (time
until sleep). Any data received serially or over the RF link will restart the timer. The sleep timer value is
settable with the ST command. While the module is awake, it will send poll request transmissions every
100ms to check its parent for buffered data messages. The module returns to sleep when the sleep timer
expires, or if the SI command is sent to it. The following image shows this behavior.
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DIN
ST = Time Awake
On/Sleep
A cyclic sleep end device enters sleep mode when no serial or RF data is received for ST time .
Legend
On/Sleep
Transmitting Poll
Request
Sleep Period
The sleep period is configured based on the SP, SN, and SO commands. The following table lists the
behavior of these commands.
Command
Range
Description
SP
0x20 - 0xAF0 (x 10 ms)
(320 - 28,000 ms)
Configures the sleep period of the module.
SN
1 - 0xFFFF
Configures the number of sleep periods
multiplier.
0 - 0xFF
Defines options for sleep mode behavior.
0x02 - Always wake for full ST time
0x04 - Enable extended sleep (sleep for full
(SP * SN) time)
SO
The XBee module supports both a short cyclic sleep and an extended cyclic sleep that make use of these
commands. These two modes allow the sleep period to be configured according to the application
requirements.
Short Cyclic Sleep
In short cyclic sleep mode, the sleep behavior of the module is defined by the SP and SN commands, and
the SO command must be set to 0x00 (default) or 0x02. In short cyclic sleep mode, the SP command
defines the sleep period and is settable up to 28 seconds. When the XBee enters short cyclic sleep, it
remains in a low power state until the SP time has expired.
After the sleep period expires, the XBee sends a poll request transmission to its parent to determine if its
parent has any buffered data waiting for the end device. Since router and coordinator devices can buffer
data for end device children up to 30 seconds, the SP range (up to 28 seconds) allows the end device to poll
regularly enough to receive buffered data. If the parent has data for the end device, the end device will
start its sleep timer (ST) and continue polling every 100ms to receive data. If the end device wakes and
finds that its parent has no data for it, the end device can return to sleep immediately.
The SN command can be used to control when the On/Sleep line is asserted (high). If SN is set to 1
(default), the On/Sleep line will be set high each time the XBee wakes from sleep. Otherwise, if SN is
greater than 1, the On/Sleep line will only be set high if RF data is received, or after SN wake cycles occur.
This allows an external device to remain powered off until RF data is received, or until a number of sleep
periods have expired (SN sleep periods). This mechanism allows the XBee to wake at regular intervals to
poll its parent for data without waking an external device for an extended time (SP * SN time). This is
shown in the figure below.
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On/Sleep
(SN = 3)
On/Sleep
(SN = 1)
∆t = SP * SN
Transmitting poll request to parent
∆t = SP
∆t = SP * SN
Transmitting poll request to parent
∆t = SP
Setting SN > 1 allows the XBee to silently poll for data without asserting On /Sleep. If RF data is received
when polling, On/Sleep will immediately assert .
Legend
Sleep_RQ
Transmitting Poll
Request
Note: SP controls the packet buffer time on routers and coordinators. SP should be set on all router and
coordinator devices to match the longest end device SP time. See the XBee Router / Coordinator
Configuration section for details.
Extended Cyclic Sleep
In extended cyclic sleep operation, an end device can sleep for a multiple of SP time which can extend the
sleep time up to several days. The sleep period is configured using the SP and SN commands. The total
sleep period is equal to (SP * SN) where SP is measured in 10ms units. The SO command must be set
correctly to enable extended sleep.
Since routers and coordinators can only buffer incoming RF data for their end device children for up to 30
seconds, if an end device sleeps longer than 30 seconds, devices in the network need some indication when
an end device is awake before they can send data to it. End devices that use extended cyclic sleep should
send a transmission (such as an IO sample) when they wake to inform other devices that they are awake
and can receive data. It is recommended that extended sleep end devices set SO to wake for the full ST
time in order to provide other devices with enough time to send messages to the end device.
Similar to short cyclic sleep, end devices running in this mode will return to sleep when the sleep timer
expires, or when the SI command is received.
Transmitting RF Data
An end device may transmit data when it wakes from sleep and has joined a network. End devices transmit
directly to their parent and then wait for an acknowledgment to be received. The parent will perform any
required address and route discoveries to help ensure the packet reaches the intended destination before
reporting the transmission status to the end device.
Receiving RF Data
After waking from sleep, an end device sends a poll request to its parent to determine if the parent has any
buffered data for it. In pin sleep mode, the end device polls every 100ms while the Sleep_RQ pin is de-asserted
(low). In cyclic sleep mode, the end device will only poll once before returning to sleep unless the sleep timer
(ST) is started (serial or RF data is received). If the sleep timer is started, the end device will continue to poll
every 100ms until the sleep timer expires.
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The XBee ZB 2x6x firmware includes an adaptive polling enhancement where, if an end device receives RF data
from its parent, it sends another poll after a very short delay to check for more data. The end device continues
to poll at a faster rate as long as it receives data from its parent. This feature greatly improves data throughput
to end devices. When the end device no longer receives data from its parent, it resumes polling every 100ms.
IO Sampling
End devices can be configured to send one or more IO samples when they wake from sleep. To enable IO
sampling on an end device, the IR command must be set to a non-zero value, and at least one analog or digital
IO pin must be enabled for sampling (D0 - D9, P0-P2 commands). If IO sampling is enabled, an end device
sends an IO sample when it wakes and starts the ST timer. It will continue sampling at the IR rate until the
sleep timer (ST) has expired. See chapter 8 for details.
Waking End Devices with the Commissioning Pushbutton
If the commissioning pushbutton functionality is enabled (D0 command), a high-to-low transition on the AD0/
DIO0 pin (pin 20) will cause an end device to wake for 30 seconds. See the Commissioning Pushbutton section
in chapter 7 for details.
Parent Verification
Since an end device relies on its parent to maintain connectivity with other devices in the network, XBee end
devices include provisions to verify its connection with its parent. End devices monitor their link with their
parent when sending poll messages and after a power cycle or reset event as described below.
When an end device wakes from sleep, it sends a poll request to its parent. In cyclic sleep, if RF or serial data is
not received and the sleep timer is not started, the end device polls one time and returns to sleep for another
sleep period. Otherwise, the end device continues polling every 100ms. If the parent does not send an
acknowledgment response to three consecutive poll request transmissions, the end device assumes the parent
is out of range, and attempts to find a new parent.
After a power-up or reset event, the end device does an orphan scan to locate its parent. If the parent does not
send a response to the orphan scan, the end device attempts to find a new parent.
Rejoining
Once all devices have joined a ZigBee network, the permit-joining attribute should be disabled such that new
devices are no longer allowed to join the network. Permit-joining can be enabled later as needed for short
times. This provides some protection in preventing other devices from joining a live network.
If an end device cannot communicate with its parent, the end device must be able to join a new parent to
maintain network connectivity. However, if permit-joining is disabled in the network, the end device will not find
a device that is allowing new joins.
To overcome this problem, ZigBee supports rejoining, where an end device can obtain a new parent in the same
network even if joining is not enabled. When an end device joins using rejoining, it performs a PAN ID scan to
discover nearby networks. If a network is discovered that has the same 64-bit PAN ID as the end device, it will
join the network by sending a rejoin request to one of the discovered devices. The device that receives the
rejoin request will send a rejoin response if it can allow the device to join the network (i.e. child table not full).
The rejoin mechanism can be used to allow a device to join the same network even if permit-joining is disabled.
To enable rejoining, NJ should be set less than 0xFF on the device that will join. If NJ < 0xFF, the device
assumes the network is not allowing joining and first tries to join a network using rejoining. If multiple rejoining
attempts fail, or if NJ=0xFF, the device will attempt to join using association.
XBee Router/Coordinator Configuration
XBee routers and coordinators may require some configuration to ensure the following are set correctly:
•RF packet buffering timeout
•Child poll timeout
•Transmission timeout.
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The value of these timeouts depends on the sleep time used by the end devices. Each of these timeouts are
discussed below.
RF Packet Buffering Timeout
When a router or coordinator receives an RF data packet intended for one of its end device children, it buffers
the packet until the end device wakes and polls for the data, or until a packet buffering timeout occurs. This
timeout is settable using the SP command. The actual timeout is (1.2 * SP), with a minimum timeout of 1.2
seconds and a maximum of 30 seconds. Since the packet buffering timeout is set slightly larger than the SP
setting, SP should be set the same on routers and coordinators as it is on cyclic sleep end devices. For pin sleep
devices, SP should be set as long as the pin sleep device can sleep, up to 30 seconds.
Note: In pin sleep and extended cyclic sleep, end devices can sleep longer than 30 seconds. If end devices sleep
longer than 30 seconds, parent and non-parent devices must know when the end device is awake in order to
reliably send data. For applications that require sleeping longer than 30 seconds, end devices should transmit
an IO sample or other data when they wake to alert other devices that they can send data to the end device.
Child Poll Timeout
Router and coordinator devices maintain a timestamp for each end device child indicating when the end device
sent its last poll request to check for buffered data packets. If an end device does not send a poll request to its
parent for a certain period of time, the parent will assume the end device has moved out of range and will
remove the end device from its child table. This allows routers and coordinators to be responsive to changing
network conditions. The NC command can be issued at any time to read the number of remaining (unused) child
table entries on a router or coordinator.
The child poll timeout is settable with the SP and SN commands. SP and SN should be set such that SP * SN
matches the longest expected sleep time of any end devices in the network. The actual timeout is calculated as
(3 * SP * SN), with a minimum of 5 seconds. For networks consisting of pin sleep end devices, the SP and SN
values on the coordinator and routers should be set such that SP * SN matches the longest expected sleep
period of any pin sleep device. The 3 multiplier ensures the end device will not be removed unless 3 sleep cycles
pass without receiving a poll request. The poll timeout is settable up to a couple of months.
Adaptive Polling
The PO command determines the regular polling rate. However, if RF data has been recently received by an end
device, it is likely that yet more RF data could be on the way. Therefore, the end device will poll at a faster rate,
gradually decreasing its adaptive poll rate until polling resumes at the regular rate as defined by the PO
command.
Transmission Timeout
As mentioned in chapter 4, when sending RF data to a remote router, since routers are always on, the timeout
is based on the number of hops the transmission may traverse. This timeout it settable using the NH command.
(See chapter 4 for details.)
Since end devices may sleep for lengthy periods of time, the transmission timeout to end devices also includes
some allowance for the sleep period of the end device. When sending data to a remote end device, the
transmission timeout is calculated using the SP and NH commands. If the timeout occurs and an
acknowledgment has not been received, the source device will resend the transmission until an
acknowledgment is received, up to two more times.
The transmission timeout per attempt is:
3 * ((unicast router timeout) + (end device sleep time)), or
3 * ((50 * NH) + (1.2 * SP)), where SP is measured in 10ms units.
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Putting it all Together
Short Sleep Periods
Pin and cyclic sleep devices that sleep less than 30 seconds can receive data transmissions at any time since
their parent device(s) will be able to buffer data long enough for the end devices to wake and poll to receive the
data. SP should be set the same on all devices in the network. If end devices in a network have more than one
SP setting, SP on the routers and coordinators should be set to match the largest SP setting of any end device.
This will ensure the RF packet buffering, poll timeout, and transmission timeouts are set correctly.
Extended Sleep Periods
Pin and cyclic sleep devices that might sleep longer than 30 seconds cannot receive data transmissions reliably
unless certain design approaches are taken. Specifically, the end devices should use IO sampling or another
mechanism to transmit data when they wake to inform the network they can receive data. SP and SN should be
set on routers and coordinators such that (SP * SN) matches the longest expected sleep time. This configures
the poll timeout so end devices are not expired from the child table unless a poll request is not received for 3
consecutive sleep periods.
As a general rule of thumb, SP and SN should be set the same on all devices in almost all cases.
Sleep Examples
This section covers some sample XBee configurations to support different sleep modes. Several AT commands are
listed with suggested parameter values. The notation in this section includes an '=' sign to indicate what each
command register should be set to - for example, SM=4. This is not the correct notation for setting command values
in the XBee. In AT command mode, each command is issued with a leading 'AT' and no '=' sign - for example ATSM4.
In the API, the two byte command is used in the command field, and parameters are populated as binary values in
the parameter field.
Example 1
Configure a device to sleep for 20 seconds, but set SN such that the On/Sleep line will remain deasserted for up to 1 minute.
The following settings should be configured on the end device.
SM = 4 (cyclic sleep) or 5 (cyclic sleep, pin wake)
SP = 0x7D0 (2000 decimal). This causes the end device to sleep for 20 seconds since SP is measured in units of
10ms.
SN = 3. (With this setting, the On/Sleep pin will assert once every 3 sleep cycles, or when RF data is received)
SO = 0
All router and coordinator devices on the network should set SP to match SP on the end device. This ensures
that RF packet buffering times and transmission timeouts will be set correctly.
Since the end device wakes after each sleep period (ATSP), the SN command can be set to 1 on all routers and
the coordinator.
Example 2
Configure an end device to sleep for 20 seconds, send 4 IO samples in 2 seconds, and return to
sleep.
Since SP is measured in 10ms units, and ST and IR are measured in 1ms units, configure an end device with the
following settings:
SM = 4 (cyclic sleep) or 5 (cyclic sleep, pin wake)
SP = 0x7D0 (2000 decimal). This causes the end device to sleep for 20 seconds.
SN = 1
SO = 0
ST = 0x7D0 (2000 decimal). This sets the sleep timer to 2 seconds.
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IR = 0x258 (600 decimal). Set IR to a value greater than (2 seconds / 4) to get 4 samples in 2 seconds. The
end device sends an IO sample at the IR rate until the sleep timer has expired.
At least one analog or digital IO line must be enabled for IO sampling to work. To enable pin 19 (AD1/DIO1) as
a digital input line, the following must be set:
D1 = 3
All router and coordinator devices on the network should set SP to match SP on the end device. This ensures
that RF packet buffering times and transmission timeouts will be set correctly.
Example 3
Configure a device for extended sleep: to sleep for 4 minutes.
SP and SN must be set such that SP * SN = 4 minutes. Since SP is measured in 10ms units, the following
settings can be used to obtain 4 minute sleep.
SM = 4 (cyclic sleep) or 5 (cyclic sleep, pin wake)
SP = 0x7D0 (2000 decimal, or 20 seconds)
SN = 0x0B (12 decimal)
SO = 0x04 (enable extended sleep)
With these settings, the module will sleep for SP * SN time, or (20 seconds * 12) = 240 seconds = 4 minutes.
For best results, the end device should send a transmission when it wakes to inform the coordinator (or
network) when it wakes. It should also remain awake for a short time to allow devices to send data to it. The
following are recommended settings.
ST = 0x7D0 (2 second wake time)
SO = 0x06 (enable extended sleep and wake for ST time)
IR = 0x800 (send 1 IO sample after waking). At least one analog or digital IO sample should be enabled for IO
sampling.
With these settings, the end device will wake after 4 minutes and send 1 IO sample. It will then remain awake
for 2 seconds before returning to sleep.
SP and SN should be set to the same values on all routers and coordinators that could allow the end device to
join. This will ensure the parent does not timeout the end device from its child table too quickly.
The SI command can optionally be sent to the end device to cause it to sleep before the sleep timer expires.
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8. XBee Analog and Digital IO Lines
XBee ZB firmware supports a number of analog and digital IO pins that are configured through software commands.
Analog and digital IO lines can be set or queried. The following table lists the configurable IO pins and the corresponding
configuration commands.
Module Pin Names Module Pin Numbers Configuration Command
CD/DIO12
P2
PWM0/RSSIM/DIO10
P0
PWM/DIO11
P1
DIO4
11
D4
CTS/DIO7
12
D7
ASSOC/DIO5
15
D5
RTS/DIO6
16
D6
AD3/DIO3
17
D3
AD2/DIO2
18
D2
AD1/DIO1
19
DI
AD0/DIO0
20
D0
IO Configuration
To enable an analog or digital IO function on one or more XBee module pin(s), the appropriate configuration
command must be issued with the correct parameter. After issuing the configuration command, changes must be
applied on the module for the IO settings to take effect.
Pin Command Parameter
Description
Unmonitored digital input
Reserved for pin-specific alternate functionalities
Analog input, single ended (A/D pins only)
Digital input, monitored
Digital output, default low
Digital output, default high
6-9
Alternate functionalities, where applicable
Pull-up resistors can be set for each digital input line using the PR command. The PR value updates the state of all
pull-up resistors.
IO Sampling
The XBee ZB modules have the ability to monitor and sample the analog and digital IO lines. IO samples can be read
locally or transmitted to a remote device to provide indication of the current IO line states. (Only API firmware
devices can send remote IO sample data out their UART.)
There are three ways to obtain IO samples, either locally or remotely:
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•Queried Sampling
•Periodic Sampling
•Change Detection Sampling.
IO sample data is formatted as shown in the table below
Bytes
Name
Sample Sets
Description
Number of sample sets in the packet. (Always set to 1.)
Indicates which digital IO lines have sampling enabled. Each bit corresponds to one
digital IO line on the module.
• bit 0 = AD0/DIO0
• bit 1 = AD1/DIO1
• bit 2 = AD2/DIO2
• bit 3 = AD3/DIO3
• bit 4 = DIO4
• bit 5 = ASSOC/DIO5
Digital Channel Mask
• bit 6 = RTS/DIO6
• bit 7 = CTS/GPIO7
• bit 8 = N/A
• bit 9 = N/A
• bit 10 = RSSI/DIO10
• bit 11 = PWM/DIO11
• bit 12 = CD/DIO12
For example, a digital channel mask of 0x002F means DIO0,1,2,3, and 5 are enabled
as digital IO.
Indicates which lines have analog inputs enabled for sampling. Each bit in the analog
channel mask corresponds to one analog input channel.
• bit 0 = AD0/DIO0
Analog Channel Mask
Variable Sampled Data Set
•
bit 1 = AD1/DIO1
•
bit 2 = AD2/DIO2
•
bit 3 = AD3/DIO3
•
bit 7 = Supply Voltage
A sample set consisting of 1 sample for each enabled ADC and/or DIO channel,
which has voltage inputs of 1143.75 and 342.1875mV.
If any digital IO lines are enabled, the first two bytes of the data set indicate the state
of all enabled digital IO. Only digital channels that are enabled in the Digital Channel
Mask bytes have any meaning in the sample set. If no digital IO are enabled on the
device, these 2 bytes will be omitted.
Following the digital IO data (if any), each enabled analog channel will return 2 bytes.
The data starts with AIN0 and continues sequentially for each enabled analog input
channel up to AIN3, and the supply voltage (if enabled) at the end.
The sampled data set will include 2 bytes of digital IO data only if one or more IO lines on the device are configured
as digital IO. If no pins are configured as digital IO, these 2 bytes will be omitted.
The digital IO data is only relevant if the same bit is enabled in the digital IO mask.
Analog samples are returned as 10-bit values. The analog reading is scaled such that 0x0000 represents 0V, and
0x3FF = 1.2V. (The analog inputs on the module cannot read more than 1.2V.) Analog samples are returned in order
starting with AIN0 and finishing with AIN3, and the supply voltage. Only enabled analog input channels return data
as shown in the figure below.
To convert the A/D reading to mV, do the following:
AD(mV) = (A/D reading * 1200mV) / 1023
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The reading in the sample frame represents voltage inputs of 1143.75 and 342.1875mV for AD0 and AD1
respectively.
Queried Sampling
The IS command can be sent to a device locally, or to a remote device using the API remote command frame
(see chapter 8 for details). When the IS command is sent, the receiving device samples all enabled digital IO
and analog input channels and returns an IO sample. If IS is sent locally, the IO sample is sent out the UART. If
the IS command was received as a remote command, the IO sample is sent over-the-air to the device that sent
the IS command.
If the IS command is issued in AT firmware, the module returns a carriage return-delimited list containing the
above-listed fields. The API firmware returns an AT command response packet with the IO data included in the
command data portion of the response frame.
The following table shows an example of the fields in an IS response.
Example
Sample AT Response
0x01
[1 sample set]
0x0C0C
[Digital Inputs: DIO 2, 3, 10, 11 low]
0x03
[Analog Inputs: A/D 0, 1]
0x0408
[Digital input states: DIO 3, 10 high, DIO 2, 11 low]
0x03D0
[Analog input ADIO 0= 0x3D0]
0x0124
[Analog input ADIO 1=0x120]
Periodic IO Sampling
Periodic sampling allows an XBee/XBee-PRO module to take an IO sample and transmit it to a remote device at
a periodic rate. The periodic sample rate is set by the IR command. If IR is set to 0, periodic sampling is
disabled. For all other values of IR, data will be sampled after IR milliseconds have elapsed and transmitted to a
remote device. The DH and DL commands determine the destination address of the IO samples. DH and DL can
be set to 0 to transmit to the coordinator, or to the 64-bit address of the remote device (SH and SL). Only
devices running API firmware can send IO data samples out their UART. Devices running AT firmware will
discard received IO data samples.
A sleeping end device will transmit periodic IO samples at the IR rate until the ST timer expires and the device
can resume sleeping.
Change Detection Sampling
Modules can be configured to transmit a data sample immediately whenever a monitored digital IO pin changes
state. The IC command is a bitmask that can be used to set which digital IO lines should be monitored for a
state change. If one or more bits in IC is set, an IO sample will be transmitted as soon as a state change is
observed in one of the monitored digital IO lines. Change detection samples are transmitted to the 64-bit
address specified by DH and DL.
RSSI PWM
The XBee module features an RSSI/PWM pin (pin 6) that, if enabled, will adjust the PWM output to indicate the
signal strength of the last received packet. The P0 (P-zero) command is used to enable the RSSI pulse width
modulation (PWM) output on the pin. If P0 is set to 1, the RSSI/PWM pin will output a pulse width modulated signal
where the frequency is adjusted based on the received signal strength of the last packet. Otherwise, for all other P0
settings, the pin can be used for general purpose IO.
When a data packet is received, if P0 is set to enable the RSSI/PWM feature, the RSSI PWM output is adjusted based
on the RSSI of the last packet. The RSSI/PWM output will be enabled for a time based on the RP command. Each
time an RF packet is received, the RSSI/PWM output is adjusted based on the RSSI of the new packet, and the RSSI
timer is reset. If the RSSI timer expires, the RSSI/PWM pin is driven low. RP is measured in 100ms units and
defaults to a value of 40 (4 seconds).
The RSSI PWM runs at 12MHz and has 2400 total counts (200us period).
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RSSI (in dBm) is converted to PWM counts using the following equation:
PWM counts = (41 * RSSI_Unsigned) - 5928
IO Examples
Example 1: Configure the following IO settings on the XBee.
Configure AD1/DIO1 as a digital input with pullup resistor enabled
Configure AD2/DIO2 as an analog input
Configure DIO4 as a digital output, driving high.
To configure AD1/DIO1 as an input, issue the ATD1 command with a parameter of 3 ("ATD13"). To enable pullup resistors on the same pin, the PR command should be issued with bit 3 set (e.g. ATPR8, ATPR1FFF, etc.).
The ATD2 command should be issued with a parameter of 2 to enable the analog input ("ATD22"). Finally, DIO4
can be set as an output, driving high by issuing the ATD4 command with a parameter value of 5 ("ATD45").
After issuing these commands, changes must be applied before the module IO pins will be updated to the new
states. The AC or CN commands can be issued to apply changes (e.g. ATAC).
Example 2: Calculate the PWM counts for a packet received with an RSSI of -84dBm.
RSSI = -84 = 0xAC = 172 decimal (unsigned)
PWM counts = (41 * 172) - 5928
PWM counts = 1124
With a total of 2400 counts, this yields an ON time of (1124 / 2400) = 46.8%
Example 3: Configure the RSSI/PWM pin to operate for 2 seconds after each received RF packet.
First, ensure the RSSI/PWM functionality is enabled by reading the P0 (P-zero) command. It should be set to 1
(default).
To configure the duration of the RSSI/PWM output, set the RP command. To achieve a 2 second PWM output, set
RP to 0x14 (20 decimal, or 2 seconds) and apply changes (AC command).
After applying changes, all received RF data packets should set the RSSI timer for 2 seconds.
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9. API Operation
As an alternative to Transparent Operation, API (Application Programming Interface) Operations are available. API
operation requires that communication with the module be done through a structured interface (data is communicated in
frames in a defined order). The API specifies how commands, command responses and module status messages are sent
and received from the module using a UART Data Frame.
Please note that Digi may add new API frames to future versions of firmware, so please build into your software interface
the ability to filter out additional API frames with unknown Frame Types.
API Frame Specifications
Two API modes are supported and both can be enabled using the AP (API Enable) command. Use the following AP
parameter values to configure the module to operate in a particular mode:
•AP = 1: API Operation
•AP = 2: API Operation (with escaped characters)
API Operation (AP parameter = 1)
When this API mode is enabled (AP = 1), the UART data frame structure is defined as follows:
UART Data Frame Structure:
Start Delimiter
(Byte 1)
0x7E
Length
(Bytes 2-3)
MSB
LSB
Frame Data
(Bytes 4-n)
Checksum
(Byte n + 1)
API-specific Structure
1 Byte
MSB = Most Significant Byte, LSB = Least Significant Byte
Any data received prior to the start delimiter is silently discarded. If the frame is not received correctly or if
the checksum fails, the module will reply with a module status frame indicating the nature of the failure.
API Operation - with Escape Characters (AP parameter = 2)
When this API mode is enabled (AP = 2), the UART data frame structure is defined as follows:
UART Data Frame Structure ‐ with escape control characters:
Start Delimiter
(Byte 1)
0x7E
Length
(Bytes 2-3)
MSB
LSB
Frame Data
(Bytes 4-n)
Checksum
(Byte n + 1)
API-specific Structure
1 Byte
Characters Escaped If Needed
MSB = Most Significant Byte, LSB = Least Significant Byte
Escape characters. When sending or receiving a UART data frame, specific data values must be escaped
(flagged) so they do not interfere with the data frame sequencing. To escape an interfering data byte,
insert 0x7D and follow it with the byte to be escaped XOR’d with 0x20.
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Data bytes that need to be escaped:
•0x7E – Frame Delimiter
•0x7D – Escape
•0x11 – XON
•0x13 – XOFF
Example - Raw UART Data Frame (before escaping interfering bytes): 
0x7E 0x00 0x02 0x23 0x11 0xCB
0x11 needs to be escaped which results in the following frame: 
0x7E 0x00 0x02 0x23 0x7D 0x31 0xCB
Note: In the above example, the length of the raw data (excluding the checksum) is 0x0002 and the
checksum of the non-escaped data (excluding frame delimiter and length) is calculated as:
0xFF - (0x23 + 0x11) = (0xFF - 0x34) = 0xCB.
Length
The length field has a two-byte value that specifies the number of bytes that will be contained in the frame
data field. It does not include the checksum field.
Frame Data
Frame data of the UART data frame forms an API-specific structure as follows:
UART Data Frame & API‐specific Structure:
Start Delimiter
(Byte 1)
0x7E
Length
(Bytes 2-3)
MSB
LSB
Frame Data
(Bytes 4-n)
Checksum
(Byte n + 1)
API-specific Structure
1 Byte
API Identifier
Identifier-specific Data
cmdID
cmdData
The cmdID frame (API-identifier) indicates which API messages will be contained in the cmdData frame
(Identifier-specific data). Note that multi-byte values are sent big endian.The XBee modules support the
following API frames:
API Frame Names and Values
API Frame Names
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API ID
AT Command
0x08
AT Command - Queue Parameter Value
0x09
ZigBee Transmit Request
0x10
Explicit Addressing ZigBee Command Frame
0x11
Remote Command Request
0x17
Create Source Route
0x21
AT Command Response
0x88
Modem Status
0x8A
ZigBee Transmit Status
0x8B
ZigBee Receive Packet (AO=0)
0x90
ZigBee Explicit Rx Indicator (AO=1)
0x91
ZigBee IO Data Sample Rx Indicator
0x92
XBee Sensor Read Indicator (AO=0)
0x94
Node Identification Indicator (AO=0)
0x95
Remote Command Response
0x97
Over-the-Air Firmware Update Status
0xA0
Route Record Indicator
0xA1
Many-to-One Route Request Indicator
0xA3
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Checksum
To test data integrity, a checksum is calculated and verified on non-escaped data.
To calculate: Not including frame delimiters and length, add all bytes keeping only the lowest 8 bits of the
result and subtract the result from 0xFF.
To verify: Add all bytes (include checksum, but not the delimiter and length). If the checksum is correct,
the sum will equal 0xFF.
API Examples
Example: Create an API AT command frame to configure an XBee to allow joining (set NJ to 0xFF). The frame
should look like:
0x7E 0x00 0x05 0x08 0x01 0x4E 0x4A 0xFF 5F
Where 0x0005 = length
0x08 = AT Command API frame type
0x01 = Frame ID (set to non-zero value)
0x4E4A = AT Command ('NJ')
0xFF = value to set command to
0x5F = Checksum
The checksum is calculated as [0xFF - (0x08 + 0x01 + 0x4E + 0x4A + 0xFF)]
Example: Send an ND command to discover the devices in the PAN. The frame should look like:
0x7E 0x00 0x04 0x08 0x01 0x4E 0x44 0x64
Where 0x0004 = length
0x08 = AT Command API frame type
0x01 = Frame ID (set to non-zero value)
0x4E44 = AT command ('ND')
0x64 = Checksum
The checksum is calculated as [0xFF - (0x08 + 0x01 + 0x4E + 0x44)]
Example: Send a remote command to the coordinator to set AD1/DIO1 as a digital input (D1=3) and apply
changes to force the IO update. The API remote command frame should look like:
0x7E 0x00 0x10 0x17 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xFF 0xFE 0x02 0x44 0x31
0x03 0x70
Where
0x10 = length (16 bytes excluding checksum)
0x17 = Remote Command API frame type
0x01 = Frame ID
0x0000000000000000 = Coordinator's address (can be replaced with coordinator's actual 64-bit address if
known)
0xFFFE = 16- bit Destination Address
0x02 = Apply Changes (Remote Command Options)
0x4431 = AT command ('D1')
0x03 = Command Parameter (the parameter could also be sent as 0x0003 or 0x00000003)
0x70 = Checksum
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API UART Exchanges
AT Commands
The following image shows the API frame exchange that takes place at the UART when sending an AT command
request to read or set a module parameter. The response can be disabled by setting the frame ID to 0 in the
request.
Transmitting and Receiving RF Data
The following image shows the API exchanges that take place at the UART when sending RF data to another
device. The transmit status frame is always sent at the end of a data transmission unless the frame ID is set to
0 in the transmit request. If the packet cannot be delivered to the destination, the transmit status frame will
indicate the cause of failure. The received data frame (0x90 or 0x91) is set by the AP command.
Remote AT Commands
The following image shows the API frame exchanges that take place at the UART when sending a remote AT
command. A remote command response frame is not sent out the UART if the remote device does not receive
the remote command.
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XBee®/XBee‐PRO® ZB RF Modules
Source Routing
The following image shows the API frame exchanges that take place at the UART when sending a source routed
transmission.
Supporting the API
Applications that support the API should make provisions to deal with new API frames that may be introduced in
future releases. For example, a section of code on a host microprocessor that handles received serial API frames
(sent out the module's DOUT pin) might look like this:
void XBee_HandleRxAPIFrame(_apiFrameUnion *papiFrame){
switch(papiFrame->api_id){
case RX_RF_DATA_FRAME:
//process received RF data frame
break;
case RX_IO_SAMPLE_FRAME:
//process IO sample frame
break;
case NODE_IDENTIFICATION_FRAME:
//process node identification frame
break;
default:
//Discard any other API frame types that are not being used
break;
API Frames
The following sections illustrate the types of frames encountered while using the API.
AT Command
Frame Type: 0x08
Used to query or set module parameters on the local device. This API command applies changes after executing
the command. (Changes made to module parameters take effect once changes are applied.) The API example
below illustrates an API frame when modifying the NJ parameter value of the module
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Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
P Frame-specific Data Frame Type
Frame ID
AT Command
LSB 2 0x04
3 0x08
4 0x52 (R)
5 0x4E (N)
6 0x4A (J)
Identifies the UART data frame for the host to correlate
with a subsequent ACK (acknowledgement). If set to 0,
no response is sent.
Command Name - Two ASCII characters that identify the
AT Command.
If present, indicates the requested parameter
value to set the given register.
If no characters present, register is queried.
Parameter Value
(optional)
Checksum
Number of bytes between the length and the checksum
7 0x0D
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
The above example illustrates an AT command when querying an NJ value.
AT Command - Queue Parameter Value
Frame Type: 0x09
This API type allows module parameters to be queried or set. In contrast to the “AT Command” API type, new
parameter values are queued and not applied until either the “AT Command” (0x08) API type or the AC (Apply
Changes) command is issued. Register queries (reading parameter values) are returned immediately.
Example: Send a command to change the baud rate (BD) to 115200 baud, but don't apply
changes yet. (Module will continue to operate at the previous baud rate until changes are applied.)
Frame Fields
Start Delimiter
MSB 1 0x00
P Frame-specific Data Frame Type
Frame ID
AT Command
Parameter Value
(ATBD7 = 115200
baud)
Checksum
Example
Description
0 0x7E
Length
Offset
LSB 2 0x05
Number of bytes between the length and the checksum
3 0x09
4 0x01
5 0x42 (B)
6 0x44 (D)
Identifies the UART data frame for the host to correlate
with a subsequent ACK (acknowledgement). If set to 0,
no response is sent.
Command Name - Two ASCII characters that identify the
AT Command.
7 0x07
If present, indicates the requested parameter
value to set the given register.
If no characters present, register is queried.
8 0x68
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Note: In this example, the parameter could have been sent as a zero-padded 2-byte or 4-byte value.
ZigBee Transmit Request
Frame Type: 0x10
A Transmit Request API frame causes the module to send data as an RF packet to the specified destination.
The 64-bit destination address should be set to 0x000000000000FFFF for a broadcast transmission (to all
devices). The coordinator can be addressed by either setting the 64-bit address to all 0x00s and the 16-bit
address to 0xFFFE, OR by setting the 64-bit address to the coordinator's 64-bit address and the 16-bit address
to 0x0000. For all other transmissions, setting the 16-bit address to the correct 16-bit address can help improve
performance when transmitting to multiple destinations. If a 16-bit address is not known, this field should be
set to 0xFFFE (unknown). The Transmit Status frame (0x8B) will indicate the discovered 16-bit address, if
successful.
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The broadcast radius can be set from 0 up to NH. If set to 0, the value of NH specifies the broadcast radius
(recommended). This parameter is only used for broadcast transmissions.
The maximum number of payload bytes can be read with the NP command.
Note: if source routing is used, the RF payload will be reduced by two bytes per intermediate hop in the source
route. This example shows if escaping is disabled (AP=1).
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x16
Frame-specific Data Frame Type
Frame ID
Number of bytes between the length and the checksum
3 0x10
4 0x01
Identifies the UART data frame for the host to correlate
with a subsequent ACK (acknowledgement). If set to 0,
no response is sent.
MSB 5 0x00
6 0x13
64-bit Destination
Address
7 0xA2
8 0x00
9 0x40
10 0x0A
Set to the 64-bit address of the destination device. The
following addresses are also supported:
0x0000000000000000 - Reserved 64-bit address for the
coordinator
0x000000000000FFFF - Broadcast address
11 0x01
LSB 12 0x27
16-bit Destination
Network Address
Broadcast Radius
MSB 13 0xFF
LSB 14 0xFE
15 0x00
Set to the 16-bit address of the destination device, if
known. Set to 0xFFFE if the address is unknown, or if
sending a broadcast.
Sets maximum number of hops a
broadcast transmission can occur.
If set to 0, the broadcast radius will
be set to the maximum hops value.
Bitfield of supported transmission options. Supported
values include the following:
0x01 - Disable ACK
0x20 - Enable APS encryption (if EE=1)
0x40 - Use the extended transmission timeout for this
destination
Options
16 0x00
Enabling APS encryption decreases the maximum
number of RF payload bytes by 4 (below the value
reported by NP).
Setting the extended timeout bit causes the stack to set
the extended transmission timeout for the destination
address. (See chapter 4.)
All unused and unsupported bits must be set to 0.
17 0x54
18 0x78
19 0x44
RF Data
20 0x61
21 0x74
Data that is sent to the destination device
22 0x61
23 0x30
24 0x41
Checksum
25 0x13
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: The example above shows how to send a transmission to a module where escaping is
disabled (AP=1) with destination address 0x0013A200 40014011, payload "TxData1B". If
escaping is enabled (AP=2), the frame should look like:
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XBee®/XBee‐PRO® ZB RF Modules
0x7E 0x00 0x16 0x10 0x01 0x00 0x7D 0x33 0xA2 0x00 0x40 0x0A 0x01 0x27
0xFF 0xFE 0x00 0x00 0x54 0x78 0x44 0x61 0x74 0x61 0x30 0x41 0x7D 0x33
The checksum is calculated (on all non-escaped bytes) as [0xFF - (sum of all bytes from API frame type through
data payload)].
Example: Send a transmission to the coordinator without specifying the coordinator's 64-bit address. The API
transmit request frame should look like:
0x7E 0x00 0x16 0x10 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0xFF 0xFE 0x00 0x00 0x54
0x78 032 0x43 0x6F 0x6F 0x72 0x64 0xFC
Where 0x16 = length (22 bytes excluding checksum)
0x10 = ZigBee Transmit Request API frame type
0x01 = Frame ID (set to non-zero value)
0x0000000000000000 = Coordinator's address (can be replaced with coordinator's actual 64-bit address
if known
0xFFFE = 16-bit Destination Address
0x00 = Broadcast radius
0x00 = Options
0x547832436F6F7264 = Data payload ("Tx2Coord")
0xFC = Checksum
Explicit Addressing ZigBee Command Frame
Frame Type: 0x11
Allows ZigBee application layer fields (endpoint and cluster ID) to be specified for a data transmission.
Similar to the ZigBee Transmit Request, but also requires ZigBee application layer addressing fields to be
specified (endpoints, cluster ID, profile ID). An Explicit Addressing Request API frame causes the module to
send data as an RF packet to the specified destination, using the specified source and destination endpoints,
cluster ID, and profile ID.
The 64-bit destination address should be set to 0x000000000000FFFF for a broadcast transmission (to all
devices). The coordinator can be addressed by either setting the 64-bit address to all 0x00s and the 16-bit
address to 0xFFFE, OR by setting the 64-bit address to the coordinator's 64-bit address and the 16-bit address
to 0x0000. For all other transmissions, setting the 16-bit address to the correct 16-bit address can help improve
performance when transmitting to multiple destinations. If a 16-bit address is not known, this field should be
set to 0xFFFE (unknown). The Transmit Status frame (0x8B) will indicate the discovered 16-bit address, if
successful.
The broadcast radius can be set from 0 up to NH. If set to 0, the value of NH specifies the broadcast radius
(recommended). This parameter is only used for broadcast transmissions.
The maximum number of payload bytes can be read with the NP command. Note: if source routing is used, the
RF payload will be reduced by two bytes per intermediate hop in the source route.
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Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x1A
Frame-specific Data Frame Type
Frame ID
Number of bytes between the length and the checksum
3 0x11
4 0x01
Identifies the UART data frame for the host to correlate
with a subsequent ACK (acknowledgement). If set to 0,
no response is sent.
MSB 5 0x00
6 0x00
64-bit Destination
Address
7 0x00
8 0x00
9 0x00
10 0x00
Set to the 64-bit address of the destination device. The
following addresses are also supported:
0x0000000000000000 - Reserved 64-bit address for the
coordinator
0x000000000000FFFF - Broadcast address
11 0x00
12 0x00
16-bit Destination
Network Address
Source Endpoint
Destination Endpoint
Cluster ID
Profile ID
Broadcast Radius
MSB 13 0xFF
LSB 14 0xFE
Set to the 16-bit address of the destination device, if
known. Set to 0xFFFE if the address is unknown, or if
sending a broadcast.
15 0xA0
Source endpoint for the transmission.
16 0xA1
Destination endpoint for the
transmission.
17 0x15
18 0x54
19 0xC1
20 0x05
21 0x00
Cluster ID used in the transmission
Profile ID used in the transmission
Sets the maximum number of hops a broadcast
transmission can traverse. If set to 0, the transmission
radius will be set to the network maximum hops value.
Bitfield of supported transmission options. Supported
values include the following:
0x01 - Disable ACK
0x20 - Enable APS encryption (if EE=1)
0x40 - Use the extended transmission timeout for this
destination
Transmit Options
22 0x00
Enabling APS encryption decreases the maximum
number of RF payload bytes by 4 (below the value
reported by NP).
Setting the extended timeout bit causes the stack to set
the extended transmission timeout for the destination
address. (See chapter 4.)
All unused and unsupported bits must be set to 0.
23 0x54
24 0x78
Data Payload
25 0x44
26 0x61
Data that is sent to the destination device
27 0x74
28 0x61
Checksum
29 0x3A
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Send a data transmission to the coordinator (64-bit address of 0x00s) using a source
endpoint of 0xA0, destination endpoint 0xA1, cluster ID =0x1554, and profile ID 0xC105. Payload
will be "TxData".
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Remote AT Command Request
Frame Type: 0x17
Used to query or set module parameters on a remote device. For parameter changes on the remote device to
take effect, changes must be applied, either by setting the apply changes options bit, or by sending an AC
command to the remote.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x10
Frame-specific Data Frame Type
Frame ID
Number of bytes between the length and the checksum
3 0x17
4 0x01
Identifies the UART data frame for the host to correlate
with a subsequent ACK (acknowledgement). If set to 0,
no response is sent.
MSB 5 0x00
6 0x13
64-bit Destination
Address
7 0xA2
8 0x00
9 0x40
10 0x40
Set to the 64-bit address of the destination device. The
following addresses are also supported:
0x0000000000000000 - Reserved 64-bit address for the
coordinator
0x000000000000FFFF - Broadcast address
11 0x11
LSB 12 0x22
16-bit Destination
Network Address
Remote Command
Options
AT Command
Command Parameter
Checksum
MSB 13 0xFF
LSB 14 0xFE
Set to the 16-bit address of the destination device, if
known. Set to 0xFFFE if the address is unknown, or if
sending a broadcast.
Bitfield to enable various remote command options.
Supported values include:
0x01 - Disable ACK
0x02 - Apply changes on remote. (If
not set, AC command must be sent
0x02 (apply before changes will take effect.)
15
changes)
0x40 - Use the extended transmission timeout for this
destination.
Setting the extended timeout bit causes the stack to set
the extended transmission timeout for the destination
address (see chapter 4).
All unused and unsupported bits must be set to 0.
16 0x42 (B)
17 0x48 (H)
Name of the
command
18 0x01
If present, indicates the requested
parameter value to set the given
register. If no characters present,
the register is queried.
19 0xF5
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Send a remote command to change the broadcast hops register on a remote device to
1 (broadcasts go to 1-hop neighbors only), and apply changes so the new configuration value
immediately takes effect. In this example, the 64-bit address of the remote is 0x0013A200
40401122, and the destination 16-bit address is unknown.
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Create Source Route
Frame Type: 0x21
This frame creates a source route in the module. A source route specifies the complete route a packet should
traverse to get from source to destination. Source routing should be used with many-to-one routing for best
results.
Note: Both the 64-bit and 16-bit destination addresses are required when creating a source route. These are
obtained when a Route Record Indicator (0xA1) frame is received.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x14
Frame-specific Data Frame Type
Frame ID
Number of bytes between the length and the checksum
3 0x21
4 0x00
The Frame ID should always be set to 0.
MSB 5 0x00
6 0x13
64-bit Destination
Address
7 0xA2
8 0x00
9 0x40
10 0x40
Set to the 64-bit address of the destination device. The
following addresses are also supported:
0x0000000000000000 - Reserved 64-bit address for the
coordinator
0x000000000000FFFF - Broadcast address
11 0x11
LSB 12 0x22
16-bit Destination
Network Address
MSB 13 0x33
LSB 14 0x44
Route Command
Options
15 0x00
Set to 0.
Number of Addresses
16 0x03
The number of addresses in the
source route (excluding source
and destination).
Address 1
Address 2 (closer hop
17 0xEE
18 0xFF
19 0xCC
20 0xDD
Address 3
Checksum
Set to the 16-bit address of the destination device, if
known. Set to 0xFFFE if the address is unknown, or if
sending a broadcast.
21 0xAA
22 0xBB
23 0x01
(neighbor of
destination)
Address of intermediate hop
(neighbor of source)
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Intermediate hop addresses must be ordered starting with the neighbor of the
destination, and working closer to the source. For example, suppose a route is found between A
and E as shown below.
A'B'C'D'E
If device E has the 64-bit and 16-bit addresses of 0x0013A200 40401122 and 0x3344, and if devices B, C, and
D have the following 16-bit addresses:
B = 0xAABB
C = 0xCCDD
D = 0xEEFF
The example above shows how to send the Create Source Route frame to establish a source route between A
and E.
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XBee®/XBee‐PRO® ZB RF Modules
AT Command Response
Frame Type: 0x88
In response to an AT Command message, the module will send an AT Command Response message. Some
commands will send back multiple frames (for example, the ND (Node Discover) command).
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x05
Frame Type
3 0x88
Frame ID
4 0x01
AT Command
a Frame-specific Data
Command Status
5 ‘B’ = 0x42
6 ‘D’ = 0x44
7 0x00
Identifies the UART data frame being reported. Note: If
Frame ID = 0 in AT Command Mode, no AT Command
Response will be given.
Command Name - Two ASCII characters that identify the
AT Command.
0 = OK
1 = ERROR
2 = Invalid Command
3 = Invalid Parameter
4 = Tx Failure
Register data in binary format. If the register was set,
then this field is not returned, as in this example.
Command Data
Checksum
Number of bytes between the length and the checksum
8 0xF0
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose the BD parameter is changed on the local device with a frame ID of 0x01. If
successful (parameter was valid), the above response would be received.
Modem Status
Frame Type: (0x8A)
RF module status messages are sent from the module in response to specific conditions.
Example: The following API frame is returned when an API coordinator forms a network.
Frame Fields
Start Delimiter
MSB 1 0x00
LSB 2 0x02
Frame Type
t Checksum
Example
Description
0 0x7E
Length
I Frame-specific Data
Offset
Status
Number of bytes between the length and the checksum
3 0x8A
4 0x06
0 = Hardware reset
1 = Watchdog timer reset
2 =Joined network (routers and end devices)
3 =Disassociated
6 =Coordinator started
7 = Network security key was updated
0x0D = Voltage supply limit exceeded (PRO S2B only)
0x11 = Modem configuration changed while join in
progress
0x80+ = stack error
5 0x6F
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Note: New modem status codes may be added in future firmware releases.
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XBee®/XBee‐PRO® ZB RF Modules
ZigBee Transmit Status
Frame Type: 0x8B
When a TX Request is completed, the module sends a TX Status message. This message will indicate if the
packet was transmitted successfully or if there was a failure.
Frame Fields
Start Delimiter
Offset
Example
Length
MSB 1 0x00
LSB 2 0x07
Frame Type
3 0x8B
Frame ID
4 0x01
5 0x7D
Identifies the UART data frame being reported. Note: If
Frame ID = 0 in AT Command Mode, no AT Command
Response will be given.
16-bit Network Address the
packet was delivered to (if
success). If not success, this
address matches the
Destination Network Address
that was provided in the
Transmit Request Frame.
6 0x84
Transmit Retry Count
7 0x00
The number of application
transmission retries that
took place.
8 0x00
0x00 = Success
0x01 = MAC ACK Failure
0x02 = CCA Failure
0x15 = Invalid destination
endpoint
0x21 = Network ACK Failure
0x22 = Not Joined to Network
0x23 = Self-addressed
0x24 = Address Not Found
0x25 = Route Not Found
0x26 = Broadcast source failed to hear a neighbor relay
the message
0x2B = Invalid binding table index
0x2C = Resource error lack of free buffers, timers, etc.
0x2D = Attempted broadcast with APS transmission
0x2E = Attempted unicast with APS transmission, but
EE=0
0x32 = Resource error lack of free buffers, timers, etc.
0x74 = Data payload too large
0x75 = Indirect message unrequested
9 0x01
0x00 = No Discovery
Overhead
0x01 = Address Discovery
0x02 = Route Discovery
0x03 = Address and Route
0x40 = Extended Timeout
Discovery
Delivery Status
Discovery Status
Checksum
Number of bytes between the length and the checksum
16-bit address of
destination
a Frame-specific Data
Description
0 0x7E
10 0x71
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose a unicast data transmission was sent to a destination device with a 16-bit
address of 0x7D84. (The transmission could have been sent with the 16-bit address set to 0x7D84
or 0xFFFE.)
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XBee®/XBee‐PRO® ZB RF Modules
ZigBee Receive Packet
Frame Type: (0x90)
When the module receives an RF packet, it is sent out the UART using this message type.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x11
Frame Type
Number of bytes between the length and the checksum
3 0x90
MSB 4 0x00
5 0x13
64-bit Source
Address
6 0xA2
7 0x00
8 0x40
9 0x52
64-bit address of sender. Set to 0xFFFFFFFFFFFFFFFF
(unknown 64-bit address) if the sender's 64-bit address is
unknown.
10 0x2B
LSB 11 0xAA
16-bit Source
Network Address
a Frame-specific Data
Receive Options
MSB 12 0x7D
LSB 13 0x84
14 0x01
16-bit address of sender
0x01 - Packet Acknowledged
0x02 - Packet was a broadcast packet
0x20 - Packet encrypted with APS encryption
0x40 - Packet was sent from an end device (if known)
Note: Option values can be combined. For example, a
0x40 and a 0x01 will show as a 0x41. Other possible
values 0x21, 0x22, 0x41, 0x42, 0x60, 0x61, 0x62.
15 0x52
16 0x78
Received Data
17 0x44
18 0x61
Received RF data
19 0x74
20 0x61
Checksum
21 0x0D
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose a device with a 64-bit address of 0x0013A200 40522BAA, and 16-bit address
0x7D84 sends a unicast data transmission to a remote device with payload "RxData". If AO=0 on
the receiving device, it would send the above example frame out its UART.
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XBee®/XBee‐PRO® ZB RF Modules
ZigBee Explicit Rx Indicator
Frame Type:0x91
When the modem receives a ZigBee RF packet it is sent out the UART using this message type (when AO=1).
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
Number of bytes between the length and the checksum
LSB 2 0x18
Frame Type
3 0x91
MSB 4 0x00
5 0x13
64-bit Source
Address
6 0xA2
7 0x00
8 0x40
64-bit address of sender. Set to 0xFFFFFFFFFFFFFFFF
(unknown 64-bit address) if the sender's 64-bit address is
unknown.
9 0x52
10 0x2B
LSB 11 0xAA
16-bit Source
Network Address
MSB 12 0x7D
Source Endpoint
14 0xE0
Endpoint of the source that initiated the
transmission
15 0xE0
Endpoint of the destination the message is
addressed to.
c Frame-specific Data Destination Endpoint
Cluster ID
Profile ID
Receive Options
LSB 13 0x84
16 0x22
17 0x11
18 0xC1
19 0x05
20 0x02
16-bit address of sender.
Cluster ID the packet was addressed
to.
Profile ID the packet was
addressed to.
0x01 – Packet Acknowledged
0x02 – Packet was a broadcast packet
0x20 - Packet encrypted with APS encryption
0x40 - Packet was sent from an end device (if known)
21 0x52
22 0x78
Received Data
23 0x44
24 0x61
Received RF data
25 0x74
26 0x61
Checksum
27 0x52
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose a device with a 64-bit address of 0x0013A200 40522BAA, and 16-bit address
0x7D84 sends a broadcast data transmission to a remote device with payload "RxData". Suppose
the transmission was sent with source and destination endpoints of 0xE0, cluster ID=0x2211, and
profile ID=0xC105. If AO=1 on the receiving device, it would send the above frame out its UART.
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XBee®/XBee‐PRO® ZB RF Modules
ZigBee IO Data Sample Rx Indicator
Frame Type: 0x92
When the module receives an IO sample frame from a remote device, it sends the sample out the UART using
this frame type (when AO=0). Only modules running API firmware will send IO samples out the UART.
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
Number of bytes between the length and the checksum
LSB 2 0x14
Frame Type
3 0x92
MSB 4 0x00
5 0x13
6 0xA2
64-bit Source
Address
7 0x00
8 0x40
64-bit address of sender
9 0x52
10 0x2B
LSB 11 0xAA
16-bit Source
Network Address
MSB 12 0x7D
LSB 13 0x84
Receive Options
Number of Samples
a Frame-specific Data
Digital Channel Mask*
14 0x01
0x01 - Packet Acknowledged
0x02 - Packet was a broadcast packet
15 0x01
Number of sample sets
included in the payload.
(Always set to 1)
16 0x00
17 0x1C
Analog Channel
Mask**
18 0x02
19 0x00
Digital Samples (if
included)
20 0x14
21 0x02
Analog Sample
22 0x25
Checksum
**
16-bit address of sender.
23 0xF5
Bitmask field that indicates
which digital IO lines on the
remote have sampling
enabled (if any).
Bitmask field that indicates
which analog IO lines on the
remote have sampling
enabled (if any).
If the sample set includes any digital IO lines
(Digital Channel Mask > 0), these two bytes
contain samples for all enabled digital IO lines.
DIO lines that do not have sampling enabled
return 0. Bits in these 2 bytes map the same as
they do in the Digital Channels Mask field.
If the sample set includes any analog input lines
(Analog Channel Mask > 0), each enabled analog input
returns a 2-byte value indicating the A/D measurement
of that input. Analog samples are ordered sequentially
from AD0/DIO0 to AD3/DIO3, to the supply voltage.
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
N/A
N/A
N/A
CD/DIO
12
CTS/DI RTS/DI ASSOC/ DIO4
O7
O6
DIO5
PWM/DI RSSI/DI N/A
N/A
O11
O10
AD3/DI AD2/DI AD1/DI AD0/DI
O3
O2
O1
O0
Supply
Voltage
N/A
N/A
AD3
© 2011 Digi International, Inc.
N/A
AD2
AD1
AD0
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Example: Suppose an IO sample is received with analog and digital IO, from a remote with a 64bit address of 0x0013A200 40522BAA and a 16-bit address of 0x7D84. If pin AD1/DIO1 is enabled
as an analog input, AD2/DIO2 and DIO4 are enabled as a digital inputs (currently high), and AD3/
DIO3 is enabled as a digital output (low) the IO sample is shown in the API example in the table
above.
XBee Sensor Read Indicator
Frame Type: 0x94
When the module receives a sensor sample (from a Digi 1-wire sensor adapter), it is sent out the UART using
this message type (when AO=0).
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
Number of bytes between the length and the checksum
LSB 2 0x17
Frame Type
3 0x94
MSB 4 0x00
5 0x13
64-bit Source
Address
6 0xA2
7 0x00
8 0x40
64-bit address of sender
9 0x52
10 0x2B
LSB 11 0xAA
16-bit Source
Network Address
Receive Options
a Frame-specific Data
1-Wire
Sensors
MSB 12 0xDD
LSB 13 0x6C
16-bit address of sender.
14 0x01
0x01 - Packet Acknowledged
0x02 - Packet was a broadcast packet
15 0x03
0x01 = A/D Sensor Read
0x02 = Temperature Sensor Read
0x60 = Water present (module CD pin low)
16 0x00
17 0x02
18 0x00
A/D Values
19 0xCE
20 0x00
21 0xEA
Indicates a two-byte value for each of four A/D sensors
(A, B, C, D)
Set to 0xFFFFFFFFFFFFFFFF if no A/Ds are found.
22 0x00
23 0x52
Temperature
Read
24 0x01
25 0x6A
Checksum
26 0x8B
Indicates the two-byte value read from a digital
thermometer if present. Set to 0xFFFF if not found.
0xFF - the 0x8 bit sum of bytes from offset 3 to this byte.
Example: Suppose a 1-wire sensor sample is received from a device with a 64-bit address of
0x0013A200 40522BAA and a 16-bit address of 0xDD6C. If the sensor sample was taken from a
1-wire humidity sensor, the API frame could look like this (if AO=0):
For convenience, let's label the A/D and temperature readings as AD0, AD1, AD2, AD3, and T. Using the data in
this example:
AD0 = 0x0002
AD1 = 0x00CE
AD2 = 0x00EA
AD3 = 0x0052
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XBee®/XBee‐PRO® ZB RF Modules
T = 0x016A
To convert these to temperature and humidity values, the following equations should be used.
Temperature (°C) = (T / 16), for T < 2048
= - (T & 0x7FF) / 16, for T >= 2048
Vsupply = (AD2 * 5.1) / 255
Voutput = (AD3 * 5.1) / 255
Relative Humidity = ((Voutput / Vsupply) - 0.16) / (0.0062)
True Humidity = Relative Humidity / (1.0546 - (0.00216 * Temperature (°C)))
Looking at the sample data, we have:
Vsupply = (234 * 5.1 / 255) = 4.68
Voutput = (82 * 5.1 / 255) = 1.64
Temperature = (362 / 16) = 22.625°C
Relative H = (161.2903 * ((1.64/4.68) - 0.16)) = 161.2903 * (0.19043) = 30.71%
True H = (30.71 / (1.0546 - (0.00216 * 22.625))) = (30.71 / 1.00573) = 30.54%
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Node Identification Indicator
Frame Type: 0x95
This frame is received when a module transmits a node identification message to identify itself (when AO=0).
The data portion of this frame is similar to a network discovery response frame (see ND command).
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
Number of bytes between the length and the checksum
LSB 2 0x20
Frame Type
3 0x95
MSB 4 0x00
5 0x13
64-bit Source
Address
6 0xA2
7 0x00
8 0x40
64-bit address of sender
9 0x52
10 0x2B
LSB 11 0xAA
16-bit Source
Network Address
Frame-specific Data
MSB 12 0x7D
LSB 13 0x84
Receive Options
14 0x02
Source 16-bit
address
15 0x7D
16 0x84
16-bit address of sender.
0x01 - Packet Acknowledged
0x02 - Packet was a broadcast packet
Set to the 16-bit network address of the remote. Set to
0xFFFE if unknown.
17 0x00
18 0x13
19 0xA2
64-bit Network
address
20 0x00
21 0x40
Indicates the 64-bit address of the remote module that
transmitted the node identification frame.
22 0x52
23 0x2B
24 0xAA
NI String
25 0x20
26 0x00
Parent 16-bit
address
27 0xFF
Device Type
29 0x01
0 = Coordinator
1 = Router
2 = End Device
30 0x01
1 = Frame sent by node identification pushbutton event
(see D0 command)
2 = Frame sent after joining event occurred (see JN
command).
3 = Frame sent after power cycle event occurred (see JN
command).
Source Event
Digi Profile ID
Manufacturer ID
Checksum
Node identifier string on the remote device. The NI-String
is terminated with a NULL byte (0x00).
28 0xFE
31 0xC1
32 0x05
33 0x10
34 0x1E
35 0x1B
Indicates the 16-bit address of the remote's parent or
0xFFFE if the remote has no parent.
Set to Digi's application profile ID.
Set to Digi's Manufacturer ID.
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: If the commissioning push button is pressed on a remote router device with 64-bit
address 0x0013A200 40522BAA, 16-bit address 0x7D84, and default NI string, the following node
identification indicator would be received.
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XBee®/XBee‐PRO® ZB RF Modules
Remote Command Response
Frame Type: 0x97
If a module receives a remote command response RF data frame in response to a Remote AT Command
Request, the module will send a Remote AT Command Response message out the UART. Some commands may
send back multiple frames--for example, Node Discover (ND) command.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
MSB 1 0x00
Length
LSB 2 0x13
Frame Type
3 0x97
Frame ID
4 0x55
Number of bytes between the length and the checksum
This is the same value passed in to the request.
MSB 5 0x00
6 0x13
7 0xA2
64-bit Source
(remote) Address
8 0x00
9 0x40
The address of the remote radio returning this response.
10 0x52
11 0x2B
c Frame-specific Data 16-bit Source
(remote) Address
AT Commands
Command Status
LSB 12 0xAA
MSB 13 0x7D
LSB 14 0x84
15 0x53
16 0x4C
17 0x00
Set to the 16-bit network
address of the remote.
Set to 0xFFFE if
unknown.
Name of the command
0 = OK
1 = ERROR
2 = Invalid Command
3 = Invalid Parameter
4 = Remote Command Transmission Failed
18 0x40
Command Data
19 0x52
20 0x2B
Register data in binary format. If the register was set,
then this field is not returned.
21 0xAA
Checksum
22 0xF0
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: If a remote command is sent to a remote device with 64-bit address 0x0013A200
40522BAA and 16-bit address 0x7D84 to query the SL command, and if the frame ID=0x55, the
response is shown in the example API frame in the table above.
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Over-the-Air Firmware Update Status
Frame Type: 0xA0
The Over-the-Air Firmware Update Status frame provides a status indication of a firmware update transmission
attempt. If a query command (0x01 0x51) is sent to a target with a 64-bit address of 0x0013A200 40522BAA
through an updater with 64-bit address 0x0013A200403E0750 and 16-bit address 0x0000, the following is the
expected response.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
MSB 1 0x00
Length
LSB 2 0x16
Frame Type
Number of bytes between the length and the checksum
3 0xA0
MSB 4 0x00
5 0x13
6 0xA2
64-bit Source
(remote) Address
7 0x00
8 0x40
The address of the remote radio returning this response.
9 0x3E
10 0x07
LSB 11 0x50
16-bit Destination
Address
Receive Options
a Frame-specific Data
Bootloader Message
Type
Block Number
12 0x00
13 0x00
16-bit address of the updater device
14 0x01
0x01 - Packet Acknowledged.
0x02 - Packet was a broadcast.
15 0x52
0x06 - ACK
0x15 - NACK
0x40 - No Mac ACK
0x51 - Query (received if the bootloader is not active on
the target)
0x52 - Query Response
16 0x00
Block number used in the update request. Set to 0 if not
applicable.
17 0x00
18 0x13
19 0xA2
64-bit Target Address
20 0x00
21 0x40
64-bit Address of remote device that is being updated
(target).
22 0x52
23 0x2B
24 0xAA
Checksum
25 0x66
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
If a query request returns a 0x15 (NACK) status, the target is likely waiting for a firmware update image. If no
messages are sent to it for about 75 seconds, the target will timeout and accept new query messages.
If a query returns a 0x51 (QUERY) status, then the target's bootloader is not active and will not respond to
query messages.
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Route Record Indicator
Frame Type: 0xA1
The route record indicator is received whenever a device sends a ZigBee route record command. This is used
with many-to-one routing to create source routes for devices in a network.
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x13
Frame Type
Number of bytes between the length and the checksum
3 0xA1
MSB 4 0x00
5 0x13
64-bit Source
Address
6 0xA2
7 0x00
8 0x40
64-bit address of the device that
initiated the route record.
9 0x40
10 0x11
LSB 11 0x22
Source (updater)
c Frame-specific Data 16-bit Address
Receive Options
Number of Addresses
Address 1
Address 2 (closer hop
Address n (neighbor
of source)
Checksum
12 0x33
13 0x44
16-bit address of the
device that initiated the
route record.
14 0x01
0x01 - Packet Acknowledged.
0x02 - Packet was a broadcast.
15 0x03
The number of addresses in the
source route (excluding source
and destination).
16 0xEE
17 0xFF
18 0xCC
19 0xDD
20 0xAA
21 0xBB
22 0x80
(neighbor of
destination)
Address of intermediate hop
Two bytes per 16-bit address.
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose device E sends a route record that traverses multiple hops en route to data
collector device A as shown below.
A B C D E
If device E has the 64-bit and 16-bit addresses of 0x0013A200 40401122 and 0x3344, and if devices B, C, and
D have the following 16-bit addresses:
B = 0xAABB
C = 0xCCDD
D = 0xEEFF
The data collector will send the above API frame out its UART.
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Many-to-One Route Request Indicator
Frame Type: 0xA3
The many-to-one route request indicator frame is sent out the UART whenever a many-to-one route request is
received
Frame Fields
Start Delimiter
Offset
Example
Description
0 0x7E
MSB 1 0x00
Length
LSB 2 0x0C
Frame Type
Number of bytes between the length and the checksum
3 0xA3
MSB 4 0x00
5 0x13
c Frame-specific Data
64-bit Source
Address
7 0x00
8 0x40
64-bit address of the device that sent the many-to-one
route request
9 0x40
10 0x11
LSB 11 0x22
Source 16-bit Address
Reserved
Checksum
6 0xA2
MSB 12 0x00
LSB 13 0x00
16-bit address of the device that initiated the many-to-one
route request.
14 0x00
Set to 0.
15 0xF4
0xFF - the 8 bit sum of bytes from offset 3 to this byte.
Example: Suppose a device with a 64-bit address of 0x0013A200 40401122 and 16-bit address
of 0x0000 sends a many-to-one route request. All remote routers with API firmware that receive
the many-to-one broadcast would send the above example API frame out their UART.
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XBee®/XBee‐PRO® ZB RF Modules
Sending ZigBee Device Objects (ZDO) Commands with the API
ZigBee Device Objects (ZDOs) are defined in the ZigBee Specification as part of the ZigBee Device Profile. These
objects provide functionality to manage and map out the ZigBee network and to discover services on ZigBee
devices. ZDOs are typically required when developing a ZigBee product that will interoperate in a public profile such
as home automation or smart energy, or when communicating with ZigBee devices from other vendors. The ZDO
can also be used to perform several management functions such as frequency agility (energy detect and channel
changes - Mgmt Network Update Request), discovering routes (Mgmt Routing Request) and neighbors (Mgmt LQI
Request), and managing device connectivity (Mgmt Leave and Permit Join Request).
The following table shows some of the more prominent ZDOs with their respective cluster identifier. Each ZDO
command has a defined payload. See the "ZigBee Device Profile" section of the ZigBee Specification for details.
ZDO Command
Network Address Request
Cluster ID
0x0000
IEEE Address Request
0x0001
Node Descriptor Request
0x0002
Simple Descriptor Request
0x0004
Active Endpoints Request
0x0005
Match Descriptor Request
0x0006
Mgmt LQI Request
0x0031
Mgmt Routing Request
0x0032
Mgmt Leave Request
0x0034
Mgmt Permit Joining Request
0x0036
Mgmt Network Update Request
0x0038
The Explicit Transmit API frame (0x11) is used to send ZigBee Device Objects commands to devices in the network.
Sending ZDO commands with the Explicit Transmit API frame requires some formatting of the data payload field.
When sending a ZDO command with the API, all multiple byte values in the ZDO command (API payload) (e.g. u16,
u32, 64-bit addresses) must be sent in little endian byte order for the command to be executed correctly on a
remote device.
For an API XBee to receive ZDO responses, the AO command must be set to 1 to enable the explicit receive API
frame.
The following table shows how the Explicit API frame can be used to send an "Active Endpoints" request to discover
the active endpoints on a device with a 16-bit address of 0x1234.
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XBee®/XBee‐PRO® ZB RF Modules
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x17
Frame Type
3 0x11
Frame ID
4 0x01
Number of bytes between the length and the checksum
Identifies the UART data frame for the host to correlate
with a subsequent transmit status. If set to 0, no transmit
status frame will be sent out the UART.
MSB 5 0x00
6 0x00
7 0x00
64-bit Destination
Address
8 0x00
9 0x00
10 0x00
64-bit address of the destination device (big endian byte
order). For unicast transmissions, set to the 64-bit
address of the destination device, or to
0x0000000000000000 to send a unicast to the
coordinator. Set to 0x000000000000FFFF for broadcast.
11 0xFF
12 0xFF
MSB 13 0xFF
16-bit Destination
Network Address
LSB 14 0xFE
Source Endpoint
a Frame-specific Data
Destination Endpoint
Cluster ID
Set to 0x00 for ZDO transmissions (endpoint 0 is the
ZDO endpoint).
16 0x00
Set to 0x00 for ZDO transmissions (endpoint 0 is the
ZDO endpoint).
LSB 18 0x05
MSB 19 0x00
LSB 20 0x00
Broadcast Radius
Transmit Options
Data Payload
15 0x00
MSB 17 0x00
Profile ID
© 2011 Digi International, Inc.
Set to the cluster ID that corresponds to the ZDO
command being sent.
0x0005 = Active Endpoints Request
Set to 0x0000 for ZDO transmissions (Profile ID 0x0000
is the ZigBee Device Profile that supports ZDOs).
21 0x00
Sets the maximum number of hops a broadcast
transmission can traverse. If set to 0, the transmission
radius will be set to the network maximum hops value.
22 0x00
All bits must be set to 0.
Transaction Sequence
Number
23 0x01
ZDO Payload
24 0x34
25 0x12
Checksum
16-bit address of the destination device (big endian byte
order). Set to 0xFFFE for broadcast, or if the 16-bit
address is unknown.
26 0xA6
The required payload for a ZDO command. All multi-byte
ZDO parameter values (u16, u32, 64-bit address) must
be sent in little endian byte order.
The Active Endpoints Request includes the following
payload:
[16-bit NwkAddrOfInterest]
Note the 16-bit address in the API example (0x1234) is
sent in little endian byte order (0x3412).
0xFF minus the 8 bit sum of bytes from offset 3 to this
byte.
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XBee®/XBee‐PRO® ZB RF Modules
Sending ZigBee Cluster Library (ZCL) Commands with the API
The ZigBee Cluster Library defines a set of attributes and commands (clusters) that can be supported in multiple
ZigBee profiles. The ZCL commands are typically required when developing a ZigBee product that will interoperate in
a public profile such as home automation or smart energy, or when communicating with ZigBee devices from other
vendors. Applications that are not designed for a public profile or for interoperability applications can skip this
section.
The following table shows some prominent clusters with their respective attributes and commands.
Cluster (Cluster ID)
Attributes (Attribute ID)
Cluster ID
Basic (0x0000)
Application Version (0x0001)
Hardware Version (0x0003)
Model Identifier (0x0005)
-Reset to defaults
(0x00)
Identify (0x0003)
Identify Time (0x0000)
Identify (0x00)
Identify Query (0x01)
Time (0x000A)
Time (0x0000)
Time Status (0x0001)
Time Zone (0x0002)
Thermostat (0x0201)
Local Temperature (0x0000)
Occupancy (0x0002)
-Setpoint raise / lower
(0x00)
The ZCL defines a number of profile-wide commands that can be supported on any profile, also known as general
commands. These commands include the following.
Command (Command ID)
Description
Read Attributes (0x00)
Used to read one or
more attributes on a
remote device.
Read Attributes Response (0x01)
Generated in
response to a read
attributes command.
Write Attributes (0x02)
Used to change one
or more attributes on
a remote device.
Write Attributes Response (0x04)
Sent in response to a
write attributes
command.
Configure Reporting (0x06)
Used to configure a
device to
automatically report
on the values of one
or more of its
attributes.
Report Attributes (0x0A)
Used to report
attributes when report
conditions have been
satisfied.
Discover Attributes (0x0C)
Used to discover the
attribute identifiers on
a remote device.
Discover Attributes Response (0x0D)
Sent in response to a
discover attributes
command.
The Explicit Transmit API frame (0x11) is used to send ZCL commands to devices in the network. Sending ZCL
commands with the Explicit Transmit API frame requires some formatting of the data payload field.
When sending a ZCL command with the API, all multiple byte values in the ZCL command (API Payload) (e.g. u16,
u32, 64-bit addresses) must be sent in little endian byte order for the command to be executed correctly on a
remote device.
Note: When sending ZCL commands, the AO command should be set to 1 to enable the explicit receive API frame.
This will provide indication of the source 64- and 16-bit addresses, cluster ID, profile ID, and endpoint information
for each received packet. This information is required to properly decode received data.
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XBee®/XBee‐PRO® ZB RF Modules
The following table shows how the Explicit API frame can be used to read the hardware version attribute from a
device with a 64-bit address of 0x0013A200 40401234 (unknown 16-bit address). This example uses arbitrary
source and destination endpoints. Recall the hardware version attribute (attribute ID 0x0003) is part of the basic
cluster (cluster ID 0x0000). The Read Attribute general command ID is 0x00.
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x19
Frame Type
3 0x11
Frame ID
4 0x01
Number of bytes between the length and the checksum
Identifies the UART data frame for the host to correlate
with a subsequent transmit status. If set to 0, no transmit
status frame will be sent out the UART.
MSB 5 0x00
6 0x13
7 0xA2
64-bit
Destination
Address
8 0x00
9 0x40
10 0x40
64-bit address of the destination device (big endian byte
order). For unicast transmissions, set to the 64-bit
address of the destination device, or to
0x0000000000000000 to send a unicast to the
coordinator. Set to 0x000000000000FFFF for broadcast.
11 0x12
12 0x34
16-bit
Destination
Network
Address
MSB 13 0xFF
LSB 14 0xFE
16-bit address of the destination device (big endian byte
order). Set to 0xFFFE for broadcast, or if the 16-bit
address is unknown.
Source
Endpoint
15 0x41
Set to the source endpoint on the sending device. (0x41
arbitrarily selected).
Destination
Endpoint
16 0x42
Set to the destination endpoint on the remote device.
(0x42 arbitrarily selected)
MSB 17 0x00
P Frame-specific
Cluster ID
a Data
Profile ID
LSB 18 0x00
MSB 19 0xD1
LSB 20 0x23
Set to the cluster ID that corresponds to the ZCL
command being sent.
0x0000 = Basic Cluster
Set to the profile ID supported on the device. (0xD123
arbitrarily selected).
Broadcast
Radius
21 0x00
Sets the maximum number of hops a broadcast
transmission can traverse. If set to 0, the transmission
radius will be set to the network maximum hops value.
Transmit
Options
22 0x00
All bits must be set to 0.
Frame Control
23 0x00
Bitfield that defines the command type and other relevant
information in the ZCL command. See the ZCL
specification for details.
Transaction
Sequence
Number
24 0x01
A sequence number used to correlate a ZCL command
with a ZCL response. (The hardware version response
will include this byte as a sequence number in the
response.) The value 0x01 was arbitrarily selected.
Command ID
25 0x00
Since the frame control "frame type" bits are 00, this byte
specifies a general command. Command ID 0x00 is a
Read Attributes command.
Attribute ID
26 0x03
Data Payload
ZCL Frame
Header
ZCL Payload
27 0x00
Checksum
© 2011 Digi International, Inc.
28 0xFA
The payload for a "Read Attributes" command is a list of
Attribute Identifiers that are being read.
Note the 16-bit Attribute ID (0x0003) is sent in little
endian byte order (0x0300). All multi-byte ZCL header
and payload values must be sent in little endian byte
order.
0xFF minus the 8 bit sum of bytes from offset 3 to this
byte.
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XBee®/XBee‐PRO® ZB RF Modules
In the above example, the Frame Control field (offset 23) was constructed as follows:
Name
Bits Example Value Description
Frame Type
0-1
00 - Command acts across the entire profile
Manufacturer Specific
0 - The manufacturer code field is omitted from the ZCL Frame Header.
Direction
0 - The command is being sent from the client side to the server side.
Disable Default Response
0 - Default response not disabled
Reserved
5-7
Set to 0.
See the ZigBee Cluster Library specification for details.
Sending Public Profile Commands with the API
Commands in public profiles such as Smart Energy and Home Automation can be sent with the XBee API using the
Explicit Transmit API frame (0x11). Sending public profile commands with the Explicit Transmit API frame requires
some formatting of the data payload field. Most of the public profile commands fit into the ZigBee Cluster Library
(ZCL) architecture as described in the previous section.
The following table shows how the Explicit API frame can be used to send a demand response and load control
message (cluster ID 0x701) in the smart energy profile (profile ID 0x0109) in the revision 14 Smart Energy
specification. The message will be a "Load Control Event" (command ID 0x00) and will be sent to a device with 64bit address of 0x0013A200 40401234 with a 16-bit address of 0x5678. The event will start a load control event for
water heaters and smart appliances, for a duration of 1 minute, starting immediately.
Note: When sending public profile commands, the AO command should be set to 1 to enable the explicit receive API
frame. This will provide indication of the source 64- and 16-bit addresses, cluster ID, profile ID, and endpoint
information for each received packet. This information is required to properly decode received data.
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Frame Fields
Offset
Start Delimiter
Example
Description
0 0x7E
Length
MSB 1 0x00
LSB 2 0x19
Frame Type
3 0x11
Frame ID
4 0x01
Number of bytes between the length and the checksum
Identifies the UART data frame for the host to correlate
with a subsequent transmit status. If set to 0, no transmit
status frame will be sent out the UART.
MSB 5 0x00
6 0x13
7 0xA2
64-bit
Destination
Address
8 0x00
9 0x40
10 0x40
64-bit address of the destination device (big endian byte
order). For unicast transmissions, set to the 64-bit
address of the destination device, or to
0x0000000000000000 to send a unicast to the
coordinator. Set to 0x000000000000FFFF for broadcast.
11 0x12
12 0x34
16-bit
Destination
Network
Address
MSB 13 0x56
LSB 14 0x78
Source
Endpoint
a Frame-specific Destination
c Data
Endpoint
Cluster ID
15 0x41
Set to the source endpoint on the sending device. (0x41
arbitrarily selected).
16 0x42
Set to the destination endpoint on the remote device.
(0x42 arbitrarily selected)
MSB 17 0x07
LSB 18 0x01
MSB 19 0x01
Profile ID
16-bit address of the destination device (big endian byte
order). Set to 0xFFFE for broadcast, or if the 16-bit
address is unknown.
LSB 20 0x09
Set to the cluster ID that corresponds to the ZCL
command being sent.
0x0701 = Demand response and load control cluster ID
Set to the profile ID supported on the device.
0x0109 = Smart Energy profile ID.
Broadcast
Radius
21 0x00
Sets the maximum number of hops a broadcast
transmission can traverse. If set to 0, the transmission
radius will be set to the network maximum hops value.
Transmit
Options
22 0x00
All bits must be set to 0.
23 0x09
Bitfield that defines the command type and other relevant
information in the ZCL command. See the ZCL
specification for details.
24 0x01
A sequence number used to correlate a ZCL command
with a ZCL response. (The hardware version response
will include this byte as a sequence number in the
response.) The value 0x01 was arbitrarily selected.
25 0x00
Since the frame control "frame type" bits are 01, this byte
specifies a cluster-specific command. Command ID 0x00
in the Demand Response and Load Control cluster is a
Load Control Event command. (See Smart Energy
specification.)
Data Payload
Frame Control
ZCL Frame
Header
© 2011 Digi International, Inc.
Transaction
Sequence
Number
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XBee®/XBee‐PRO® ZB RF Modules
Frame Fields
Offset
Example
26 0x78
4-byte unique identifier.
Note the 4-byte ID is sent in little endian byte order
(0x78563412).
The event ID in this example (0x12345678) was
arbitrarily selected.
27 0x56
Issuer Event ID
28 0x34
29 0x12
30 0x14
Device Class
Utility
Enrollment
Group
Description
to apply the load control event.
A bit value of 0x0014 enables smart appliances and
water heaters.
Note the 2-byte bit field value is sent in little endian byte
order.
31 0x00
Used to identify sub-groups of devices in the deviceclass. 0x00 addresses all groups.
32 0x00
33 0x00
Start Time
34 0x00
UTC timestamp representing when the event should
start. A value of 0x00000000 indicates "now".
35 0x00
36 0x00
ZCL Payload Load Control
Event Data
Duration in
Minutes
37 0x01
Criticality Level
39 0x04
Indicates the criticality level of the event. In this example,
the level is "voluntary".
Cooling
Temperature
40 0xFF
Requested offset to apply to the normal cooling set point.
A value of 0xFF indicates the temperature offset value is
not used.
Heating
Temperature
Offset
41 0xFF
Requested offset to apply to the normal heating set point.
A value of 0xFF indicates the temperature offset value is
not used.
This 2-byte value must be sent in little endian byte order.
38 0x00
42 0x00
Cooling
Temperature
Set Point
Heating
Temperature
Set Point
Requested cooling set point in 0.01 degrees Celsius.
A value of 0x8000 means the set point field is not used in
this event.
Note the 0x80000 is sent in little endian byte order.
43 0x80
44 0x00
Requested heating set point in 0.01 degrees Celsius.
A value of 0x8000 means the set point field is not used in
this event.
Note the 0x80000 is sent in little endian byte order.
45 0x80
Maximum energy usage limit.
A value of 0x80 indicates the field is not used.
Average Load
Adjustment
Percentage
46 0x80
Duty Cycle
47 0xFF
Defines the maximum "On" duty cycle.
A value of 0xFF indicates the duty cycle is not used in this
event.
Duty Cycle
Event Control
48 0x00
A bitmap describing event options.
49 0x5B
0xFF minus the 8 bit sum of bytes from offset 3 to this
byte.
Checksum
In the above example, the Frame Control field (offset 23) was constructed as follows:
Name
Bits Example Value Description
Frame Type
0-1
01 - Command is specific to a cluster
Manufacturer Specific
0 - The manufacturer code field is omitted from the ZCL Frame Header.
Direction
1 - The command is being sent from the server side to the client side.
Disable Default Response
0 - Default response not disabled
Reserved
5-7
Set to 0.
© 2011 Digi International, Inc.
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10. XBee Command Reference Tables
Addressing
Addressing Commands
AT
Name and Description
Command
Node
Type1
Parameter Range
Default
DH
Destination Address High.Set/Get the upper 32 bits of the 64-bit destination address.
When combined with DL, it defines the 64-bit destination address for data transmission.
CRE
Special definitions for DH and DL include 0x000000000000FFFF (broadcast) and
0x0000000000000000 (coordinator).
0 - 0xFFFFFFFF
DL
Destination Address Low. Set/Get the lower 32 bits of the 64-bit destination address.
When combined with DH, it defines the 64-bit destination address for data
CRE
transmissions. Special definitions for DH and DL include 0x000000000000FFFF
(broadcast) and 0x0000000000000000 (coordinator).
0 - 0xFFFFFFFF
0xFFFF(Coordinator)
0 (Router/End Device)
MY
16-bit Network Address. Read the 16-bit network address of the module. A value of
0xFFFE means the module has not joined a ZigBee network
CRE
0 - 0xFFFE
[read-only]
0xFFFE
MP
16-bit Parent Network Address. Read the 16-bit network address of the module's
parent. A value of 0xFFFE means the module does not have a parent.
0 - 0xFFFE
[read-only]
0xFFFE
NC
Number of Remaining Children. Read the number of end device children that can join
the device. If NC returns 0, then the device cannot allow any more end device children CR
to join.
0 - MAX_CHILDREN
(maximum varies)
read-only
SH
Serial Number High. Read the high 32 bits of the module's unique 64-bit address.
CRE
0 - 0xFFFFFFFF 
[read-only]
factory-set
SL
Serial Number Low. Read the low 32 bits of the module's unique 64-bit address.
CRE
0 - 0xFFFFFFFF
[read-only]
factory-set
NI
Node Identifier. Stores a string identifier. The register only accepts printable ASCII
data. In AT Command Mode, a string can not start with a space. A carriage return ends
the command. Command will automatically end when maximum bytes for the string
CRE
have been entered. This string is returned as part of the ND (Node Discover) command.
This identifier is also used with the DN (Destination Node) command. In AT command
mode, an ASCII comma (0x2C) cannot be used in the NI string
20-Byte printable 
ASCII string
ASCII space
character (0x20)
SE
Source Endpoint. Set/read the ZigBee application layer source endpoint value. This
value will be used as the source endpoint for all data transmissions. SE is only
supported in AT firmware.The default value 0xE8 (Data endpoint) is the Digi data
endpoint
CRE
0 - 0xFF
0xE8
DE
Destination Endpoint. Set/read Zigbee application layer destination ID value. This
value will be used as the destination endpoint all data transmissions. DE is only
CRE
supported in AT firmware.The default value (0xE8) is the Digi data endpoint.
0 - 0xFF
0xE8
CI
Cluster Identifier. Set/read Zigbee application layer cluster ID value. This value will be
CRE
used as the cluster ID for all data transmissions. CI is only supported in AT
firmware.The default value0x11 (Transparent data cluster ID).
0 - 0xFFFF
0x11
NP
Maximum RF Payload Bytes. This value returns the maximum number of RF payload
bytes that can be sent in a unicast transmission. If APS encryption is used (API transmit
option bit enabled), the maximum payload size is reduced by 9 bytes. If source routing
CRE
is used (AR < 0xFF), the maximum payload size is reduced further.
Note: NP returns a hexadecimal value. (e.g. if NP returns 0x54, this is equivalent to 84
bytes)
0 - 0xFFFF
[read-only]
DD
Device Type Identifier. Stores a device type value. This value can be used to
differentiate different XBee-based devices. Digi reserves the range 0 - 0xFFFFFF.
For example, Digi currently uses the following DD values to identify various ZigBee
products:
0x30001 - ConnectPort X8 Gateway
0x30002 - ConnectPort X4 Gateway
0x30003 - ConnectPort X2 Gateway
0x30005 - RS-232 Adapter
0x30006 - RS-485 Adapter
0x30007 - XBee Sensor Adapter
0x30008 - Wall Router
0x3000A - Digital I/O Adapter
0x3000B - Analog I/O Adapter
0x3000C - XStick
0x3000F - Smart Plug
0x30011 - XBee Large Display
0x30012 - XBee Small Display
0 - 0xFFFFFFFF
0x30000
CRE
Node types that support the command: C=Coordinator, R=Router, E=End Device
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Networking
Networking Commands
AT
Name and Description
Command
Node
Type1
Parameter Range
Default
[read-only]
CH
Operating Channel. Read the channel number used for transmitting and receiving
between RF modules. Uses 802.15.4 channel numbers. A value of 0 means the device CRE
has not joined a PAN and is not operating on any channel.
XBee
0, 0x0B - 0x1A
(Channels 11-26)
XBee-PRO (S2)
0, 0x0B - 0x18
(Channels 11-24)
XBee-PRO (S2B)
0, 0x0B - 0x19
(Channels 11-25)
DA
Force Disassociation. End device will immediately disassociate from a Coordinator (if
CRE
associated) and reattempt to associate.
ID
Extended PAN ID. Set/read the 64-bit extended PAN ID. If set to 0, the coordinator will
select a random extended PAN ID, and the router / end device will join any extended
CRE
PAN ID. Changes to ID should be written to non-volatile memory using the WR
command to preserve the ID setting if a power cycle occurs.
00xFFFFFFFFFFFFFFFF
OP
Operating Extended PAN ID. Read the 64-bit extended PAN ID. The OP value reflects
CRE
the operating extended PAN ID that the module is running on. If ID > 0, OP will equal ID.
0x01 0xFFFFFFFFFFFFFFFF
[read-only]
NH
Maximum Unicast Hops. Set / read the maximum hops limit. This limit sets the
maximum broadcast hops value (BH) and determines the unicast timeout. The timeout
CRE
is computed as (50 * NH) + 100 ms. The default unicast timeout of 1.6 seconds
(NH=0x1E) is enough time for data and the acknowledgment to traverse about 8 hops.
0 - 0xFF
0x1E
BH
Broadcast Hops. Set/Read the maximum number of hops for each broadcast data
transmission. Setting this to 0 will use the maximum number of hops.
0 - 0x1E
OI
Operating 16-bit PAN ID. Read the 16-bit PAN ID. The OI value reflects the actual 16CRE
bit PAN ID the module is running on.
0 - 0xFFFF
[read-only]
NT
Node Discovery Timeout. Set/Read the node discovery timeout. When the network
discovery (ND) command is issued, the NT value is included in the transmission to
provide all remote devices with a response timeout. Remote devices wait a random
time, less than NT, before sending their response.
CRE
0x20 - 0xFF [x 100 msec]
0x3C (60d)
CRE
0 - 0x03 [bitfield]
SC
Scan Channels. Set/Read the list of channels to scan.
Coordinator - Bit field list of channels to choose from prior to starting network.
Router/End Device - Bit field list of channels that will be scanned to find a Coordinator/
Router to join.
Changes to SC should be written using WR command to preserve the SC setting if a
CRE
power cycle occurs.
Bit (Channel):
0 (0x0B)
4 (0x0F)
8 (0x13)
12 (0x17)
1 (0x0C)
5 (0x10)
9 (0x14)
13 (0x18)
2 (0x0D)
6 (0x11)
10 (0x15)
14 (0x19)
3 (0x0E)
7 (0x12)
11 (0x16)
15 (0x1A)
XBee
1 - 0xFFFF [bitfield]
XBee-PRO (S2)
1 - 0x3FFF [bitfield]
(bits 14, 15 not allowed)
XBee-PRO (S2B)
1-0x7FFF
(bit 15 is not allowed)
1FFE
SD
Scan Duration. Set/Read the scan duration exponent. Changes to SD should be
written using WR command.
Coordinator - Duration of the Active and Energy Scans (on each channel) that are
used to determine an acceptable channel and Pan ID for the Coordinator to startup on.
Router / End Device - Duration of Active Scan (on each channel) used to locate an
available Coordinator / Router to join during Association.
Scan Time is measured as:(# Channels to Scan) * (2 ^ SD) * 15.36ms - The number of
channels to scan is determined by the SC parameter. The XBee can scan up to 16
channels (SC = 0xFFFF).
CRE
Sample Scan Duration times (13 channel scan):
If SD = 0, time = 0.200 sec

SD = 2, time = 0.799 sec

SD = 4, time = 3.190 sec

SD = 6, time = 12.780 sec
Note: SD influences the time the MAC listens for beacons or runs an energy scan on a
given channel. The SD time is not a good estimate of the router/end device joining time
requirements. ZigBee joining adds additional overhead including beacon processing on
each channel, sending a join request, etc. that extend the actual joining time.
0 - 7 [exponent]
ZS
ZigBee Stack Profile. Set / read the ZigBee stack profile value. This must be set the
same on all devices that should join the same network.
0-2
NO
Network Discovery options. Set/Read the options value for the network discovery
command. The options bitfield value can change the behavior of the ND (network
discovery) command and/or change what optional values are returned in any received
ND responses or API node identification frames. Options include:
0x01 = Append DD value (to ND responses or API node identification frames)
002 = Local device sends ND response frame when ND is issued.
© 2011 Digi International, Inc.
CRE
CRE
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XBee®/XBee‐PRO® ZB RF Modules
Networking Commands
AT
Name and Description
Command
Node
Type1
Parameter Range
Default
0 - 0xFF 
[x 1 sec]
0xFF 
(always allows joining)
NJ
Node Join Time. Set/Read the time that a Coordinator/Router allows nodes to join.
This value can be changed at run time without requiring a Coordinator or Router to
restart. The time starts once the Coordinator or Router has started. The timer is reset
on power-cycle or when NJ changes.
For an end device to enable rejoining, NJ should be set less than 0xFF on the device
that will join. If NJ < 0xFF, the device assumes the network is not allowing joining and
first tries to join a network using rejoining. If multiple rejoining attempts fail, or if
NJ=0xFF, the device will attempt to join using association.
Note: Setting the NJ command will not cause the radio to broadcast the new value of
NJ out to the network via a Mgmt_Permit_Joining_req; this value is transmitted by
setting CB=2. See the command description for CB for more information.
JV
Channel Verification. Set/Read the channel verification parameter. If JV=1, a router
will verify the coordinator is on its operating channel when joining or coming up from a
power cycle. If a coordinator is not detected, the router will leave its current channel and R
attempt to join a new PAN. If JV=0, the router will continue operating on its current
channel even if a coordinator is not detected.
NW
Network Watchdog Timeout. Set/read the network watchdog timeout value. If NW is
set > 0, the router will monitor communication from the coordinator (or data collector)
and leave the network if it cannot communicate with the coordinator for 3 NW periods. R
The timer is reset each time data is received from or sent to a coordinator, or if a manyto-one broadcast is received.
0 - 0x64FF
[x 1 minute]
(up to over 17 days)
0 (disabled)
JN
Join Notification. Set / read the join notification setting. If enabled, the module will
transmit a broadcast node identification packet on power up and when joining. This
action blinks the Associate LED rapidly on all devices that receive the transmission, and RE
sends an API frame out the UART of API devices. This feature should be disabled for
large networks to prevent excessive broadcasts.
0-1
AR
Aggregate Routing Notification. Set/read time between consecutive aggregate route
broadcast messages. If used, AR may be set on only one device to enable many-to-one
CR
routing to the device. Setting AR to 0 only sends one broadcast. AR is in units of 10
seconds.
0 - 0xFF
0xFF
DJ
Disable Joining.
Setting this register to 1 will disable the device from joining. This setting is not writeable RE
(WR) and will reset to zero after a power cycle.
1 (enabled)
0 [ not writeable ]
II
Initial ID.
This register determines the operating 16-bit PAN ID for the network. Changing this
value will cause the Coordinator to leave the network and form another. A setting of
0xFFFF allows the system to choose its own 16 bit 802.15.4 PAN Identifier.
This setting is not writeable (WR) and will reset to 0xFFFF after a power cycle.
0x0000-0xFFFF
0xFFFF [ not
writeable ]
© 2011 Digi International, Inc.
CRE
0 - Channel verification
disabled
1 - Channel verification
enabled
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XBee®/XBee‐PRO® ZB RF Modules
Security
Security Commands
AT
Name and Description
Command
Node
Parameter Range
Type1
EE
Encryption Enable. Set/Read the encryption enable setting.
CRE
EO
Encryption Options. Configure options for encryption. Unused option bits should be set
to 0. Options include:
CRE
0x01 - Send the security key unsecured over-the-air during joins
0x02 - Use trust center (coordinator only
0 - 0xFF
NK
Network Encryption Key. Set the 128-bit AES network encryption key. This command
is write-only; NK cannot be read. If set to 0 (default), the module will select a random
network key.
128-bit value
KY
Link Key. Set the 128-bit AES link key. This command is write only; KY cannot be read.
Setting KY to 0 will cause the coordinator to transmit the network key in the clear to
CRE
joining devices, and will cause joining devices to acquire the network key in the clear
when joining.
128-bit value
0 - Encryption disabled
1 - Encryption enabled
Default
RF Interfacing
RF Interfacing Commands
AT
Name and Description
Command
Node
Parameter Range
Type1
Default
XBee (S2)
(boost mode disabled)
0 = -8 dBm
1 = -4 dBm
2 = -2 dBm
3 = 0 dBm
4 = +2 dBm
XBee-PRO (S2)
4 = 17 dBm
XBee-PRO (S2)
(International Variant)
4 = 10dBm
PL
Power Level. Select/Read the power level at which the RF module transmits conducted
power. For XBee-PRO (S2B) Power Level 4 is calibrated and the other power levels are
CRE
approximate. For XBee (S2), the default power level (PL=4) is guaranteed from -40 to
85° C. Other power levels are only guaranteed from 0 to 85° C.
PM
Power Mode. Set/read the power mode of the device. Enabling boost mode will improve
the receive sensitivity by 1dB and increase the transmit power by 2dB
CRE
Note: Enabling boost mode on the XBee-PRO (S2) will not affect the output power. Boost
mode imposes a slight increase in current draw. See section 1.2 for details.
0-1, 
0= -Boost mode disabled,
1= Boost mode enabled. 1
DB
Received Signal Strength. This command reports the received signal strength of the
last received RF data packet. The DB command only indicates the signal strength of the
last hop. It does not provide an accurate quality measurement for a multihop link. DB can
be set to 0 to clear it. The DB command value is measured in -dBm. For example if DB CRE
returns 0x50, then the RSSI of the last packet received was
-80dBm. As of 2x6x firmware, the DB command value is also updated when an APS
acknowledgment is received.
0 - 0xFF
Observed range for
XBee-PRO:
0x1A - 0x58
For XBee:
0x 1A - 0x5C
PP
Peak Power. Read the dBm output when maximum power is selected (PL4).
0x0-0x12
CRE
XBee-PRO (S2B)
(Boost mode enabled)
4 = 18dBM
3 = 16dBm
2 = 14dBm
1 = 12dBm
0 = 10dBm
XBee-PRO (S2B)
(International Variant)
(Boost mode enabled)
4 = 10dBm
3 = 8dBm
2 = 6dBm
1 = 4dBm
0 = 2dBm
[read only]
1. Node types that support the command: C = Coordinator, R = Router, E = End Device
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Serial Interfacing (I/O)
Serial Interfacing Commands
AT
Name and Description
Command
AP
AO
API Enable. Enable API Mode.
The AP command is only supported when using API firmware: 21xx (API coordinator),
23xx (API router), 29xx (API end device).
API Options. Configure options for API. Current options select the type of receive API
frame to send out the Uart for received RF data packets.
Node
Parameter Range
Type1
Default
CRE
1 - 2
1 = API-enabled
2 = API-enabled 
(w/escaped control
characters)
CRE
0 - Default receive API
indicators enabled
1 - Explicit Rx data
indicator API frame
enabled (0x91)
3 - enable ZDO
passthrough of ZDO
requests to the UART
which are not supported
by the stack, as well as
Simple_Desc_req,
Active_EP_req, and
Match_Desc_req.
BD
Interface Data Rate. Set/Read the serial interface data rate for communication between
the module serial port and host.
CRE
Any value above 0x07 will be interpreted as an actual baud rate. When a value above
0x07 is sent, the closest interface data rate represented by the number is stored in the
BD register.
0-7
(standard baud rates)
0 = 1200 bps
1 = 2400
2 = 4800
3 = 9600
4 = 19200
5 = 38400
6 = 57600
7 = 115200
0x80 - 0xE1000
(non-standard rates up to
921kbps)
NB
Serial Parity. Set/Read the serial parity setting on the module.
CRE
0 = No parity
1 = Even parity
2 = Odd parity
3 = Mark parity
SB
Stop Bits. Set/read the number of stop bits for the UART. (Two stop bits are not
supported if mark parity is enabled.)
CRE
0 = 1 stop bit
1 = 2 stop bits
RO
Packetization Timeout. Set/Read number of character times of inter-character silence
required before packetization. Set (RO=0) to transmit characters as they arrive instead of
CRE
buffering them into one RF packet The RO command is only supported when using AT
firmware: 20xx (AT coordinator), 22xx (AT router), 28xx (AT end device).
0 - 0xFF
[x character times]
DIO7 Configuration. Select/Read options for the DIO7 line of the RF module.
CRE
0 = Disabled
1 = CTS Flow Control
3 = Digital input
4 = Digital output, low
5 = Digital output, high
6 = RS-485 transmit
enable (low enable)
7 = RS-485 transmit
enable (high enable)
CRE
0 = Disabled
1 = RTS flow control
3 = Digital input
4 = Digital output, low
5 = Digital output, high
D7
D6
DIO6 Configuration. Configure options for the DIO6 line of the RF module.
1. Node types that support the command: C = Coordinator, R = Router, E = End Device
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
I/O Commands
I/O Commands
AT
Name and Description
Command
Node
Parameter Range
Type1
Default
IR
IO Sample Rate. Set/Read the IO sample rate to enable periodic sampling. For periodic
sampling to be enabled, IR must be set to a non-zero value, and at least one module pin
CRE
must have analog or digital IO functionality enabled (see D0-D8, P0-P2 commands). The
sample rate is measured in milliseconds.
0, 0x32:0xFFFF (ms)
IC
IO Digital Change Detection. Set/Read the digital IO pins to monitor for changes in the
IO state. IC works with the individual pin configuration commands (D0-D8, P0-P2). If a
pin is enabled as a digital input/output, the IC command can be used to force an
immediate IO sample transmission when the DIO state changes. IC is a bitmask that can
be used to enable or disable edge detection on individual channels. Unused bits should
CRE
be set to 0.
Bit (IO pin): 0 (DIO0)4 (DIO4)8 (DIO8)
1 (DIO1) 5 (DIO5) 9 (DIO9)
2 (DIO2) 6 (DIO6) 10 (DIO10)
3 (DIO3) 7 (DIO7) 11 (DIO11)
: 0 - 0xFFFF
PWM0 Configuration. Select/Read function for PWM0.
CRE
0 = Disabled
1 = RSSI PWM
3 - Digital input,
monitored
4 - Digital output, default
low
5 - Digital output, default
high
CRE
0 - Unmonitored digital
input
3- Digital input,
monitored
4- Digital output, default
low
5- Digital output, default
high
P0
P1
P2
P3
D0
D1
D2
DIO11 Configuration. Configure options for the DIO11 line of the RF module.
DIO12 Configuration. Configure options for the DIO12 line of the RF module.
DIO13 Configuration. Set/Read function for DIO13. This command is not yet
supported.
AD0/DIO0 Configuration. Select/Read function for AD0/DIO0.
AD1/DIO1 Configuration. Select/Read function for AD1/DIO1.
AD2/DIO2 Configuration. Select/Read function for AD2/DIO2.
© 2011 Digi International, Inc.
CRE
0 - Unmonitored digital
input
3- Digital input,
monitored
4- Digital output, default
low
5- Digital output, default
high
CRE
0, 3-5
0 – Disabled
3 – Digital input
4 – Digital output, low
5 – Digital output, high
CRE
1 - Commissioning button
enabled
2 - Analog input, single
ended
3 - Digital input
4 - Digital output, low
5 - Digital output, high
CRE
0, 2-5
0 – Disabled
2 - Analog input, single
ended
3 – Digital input
4 – Digital output, low
5 – Digital output, high
CRE
0, 2-5
0 – Disabled
2 - Analog input, single
ended
3 – Digital input
4 – Digital output, low
5 – Digital output, high
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I/O Commands
AT
Name and Description
Command
D3
D4
AD3/DIO3 Configuration. Select/Read function for AD3/DIO3.
DIO4 Configuration. Select/Read function for DIO4.
Node
Parameter Range
Type1
Default
CRE
0, 2-5
0 – Disabled
2 - Analog input, single
ended
3 – Digital input
4 – Digital output, low
5 – Digital output, high
CRE
0, 3-5
0 – Disabled
3 – Digital input
4 – Digital output, low
5 – Digital output, high

D5
DIO5 Configuration. Configure options for the DIO5 line of the RF module.
CRE
0 = Disabled
1 = Associated
indication LED
3 = Digital input
4 = Digital output, default
low
5 = Digital output, default
high
D8
DIO8 Configuration. Set/Read function for DIO8. This command is not yet supported. CRE
0, 3-5
0 – Disabled
3 – Digital input
4 – Digital output, low
5 – Digital output, high
LT
Assoc LED Blink Time. Set/Read the Associate LED blink time. If the Associate LED
functionality is enabled (D5 command), this value determines the on and off blink times
for the LED when the module has joined a network. If LT=0, the default blink rate will be CRE
used (500ms coordinator, 250ms router/end device). For all other LT values, LT is
measured in 10ms.
0, 0x0A - 0xFF (100 2550 ms)
PR
Pull-up Resistor. Set/read the bit field that configures the internal pull-up resistor status
for the I/O lines. "1" specifies the pull-up resistor is enabled. "0" specifies no pullup.(30k
pull-up resistors)
Bits:"
0 - DIO4 (Pin 11)
1 - AD3 / DIO3 (Pin 17)
2 - AD2 / DIO2 (Pin 18)
3 - AD1 / DIO1 (Pin 19)
4 - AD0 / DIO0 (Pin 20)
CRE
5 - RTS / DIO6 (Pin 16)
6 - DTR / Sleep Request / DIO8 (Pin 9)
7 - DIN / Config (Pin 3)
8 - Associate / DIO5 (Pin 15)
9 - On/Sleep / DIO9 (Pin 13)
10 - DIO12 (Pin 4)
11 - PWM0 / RSSI / DIO10 (Pin 6)
12 - PWM1 / DIO11 (Pin 7)
13 - CTS / DIO7 (Pin 12)
0 - 0x3FFF
0 - 0x1FFF
RP
RSSI PWM Timer. Time the RSSI signal will be output on the PWM after the last RF data
CRE
reception or APS acknowledgment.. When RP = 0xFF, output will always be on.
0 - 0xFF [x 100 ms]
0x28 (40d)
%V
Supply Voltage. Reads the voltage on the Vcc pin. Scale by 1200/1024 to convert to
mV units. For examplee, a %V reading of 0x900 (2304 decimal) represents 2700mV or
2.7OV.
-0x-0xFFFF [read only]
V+
Voltage Supply Monitoring. The voltage supply threshold is set with the V+ command.
If the measured supply voltage falls below or equal to this threshold, the supply voltage
will be included in the IO sample set. V+ is set to 0 by default (do not include the supply
voltage). Scale mV units by 1024/1200 to convert to internal units. For example, for a
2700mV threshold enter 0x900.
CRE
Given the operating Vcc ranges for different platforms, and scaling by 1024/1200, the
useful parameter ranges are:
XBee 2100-3600 mV 0,0x0700-0x0c00
PRO 3000-3400 mV, 0,0x0a00-0x0b55
S2B 2700-3600 mV, 0,0x0900-0x0c00
0-0xFFFF
TP
Reads the module temperature in Degrees Celsius. Accuracy +/- 7 degrees.
1° C = 0x0001 and -1° C = 0xFFFF. Command is only available in PRO S2B.
0x0-0xFFFF
© 2011 Digi International, Inc.
CRE
CRE
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XBee®/XBee‐PRO® ZB RF Modules
Diagnostics
Diagnostics Commands
AT
Name and Description
Command
Node
Parameter Range
Type1
Default
CRE
0 - 0xFFFF [read-only]
Factory-set
CRE
0 - 0xFFFF [read-only]
Factory-set
0 - 0xFF
[read-only]
--
Firmware Version. Read firmware version of the module.
The firmware version returns 4 hexadecimal values (2 bytes) "ABCD". Digits ABC are
the main release number and D is the revision number from the main release. "B" is a
variant designator.
VR
XBee and XBee-PRO ZB modules return:
0x2xxx versions.
XBee and XBee-PRO ZNet modules return:
0x1xxx versions. ZNet firmware is not compatible with ZB firmware.
HV
Hardware Version. Read the hardware version of the module.version of the module.
This command can be used to distinguish among different hardware platforms. The
upper byte returns a value that is unique to each module type. The lower byte indicates
the hardware revision.
XBee ZB and XBee ZNet modules return the following (hexadecimal) values:
0x19xx - XBee module
0x1Axx - XBee-PRO module
AI
Association Indication. Read information regarding last node join request:
0x00 - Successfully formed or joined a network. (Coordinators form a network, routers
and end devices join a network.)
0x21 - Scan found no PANs
0x22 - Scan found no valid PANs based on current SC and ID settings
0x23 - Valid Coordinator or Routers found, but they are not allowing joining (NJ expired)
0x24 - No joinable beacons were found
0x25 - Unexpected state, node should not be attempting to join at this time
0x27 - Node Joining attempt failed (typically due to incompatible security settings)
0x2A - Coordinator Start attempt failed‘
CRE
0x2B - Checking for an existing coordinator
0x2C - Attempt to leave the network failed
0xAB - Attempted to join a device that did not respond.
0xAC - Secure join error - network security key received unsecured
0xAD - Secure join error - network security key not received
0xAF - Secure join error - joining device does not have the right preconfigured link key
0xFF - Scanning for a ZigBee network (routers and end devices)
Note: New non-zero AI values may be added in later firmware versions. Applications
should read AI until it returns 0x00, indicating a successful startup (coordinator) or join
(routers and end devices)
1. Node types that support the command:C = Coordinator, R = Router, E = End Device
AT Command Options
AT Command Options Commands
AT
Name and Description
Command
Node
Parameter Range
Type1
Default
CT
Command Mode Timeout. Set/Read the period of inactivity (no valid commands
received) after which the RF module automatically exits AT Command Mode and returns CRE
to Idle Mode.
2 - 0x028F [x 100 ms]
0x64 (100d)
CN
Exit Command Mode. Explicitly exit the module from AT Command Mode.
--
--
GT
Guard Times. Set required period of silence before and after the Command Sequence
Characters of the AT Command Mode Sequence (GT + CC + GT). The period of silence CRE
is used to prevent inadvertent entrance into AT Command Mode.
1 - 0x0CE4 [x 1 ms]
0x3E8
(max of 3.3 decimal sec) (1000d)
CC
Command Sequence Character. Set/Read the ASCII character value to be used
between Guard Times of the AT Command Mode Sequence (GT + CC + GT). The AT
Command Mode Sequence enters the RF module into AT Command Mode.
The CC command is only supported when using AT firmware: 20xx (AT coordinator),
22xx (AT router), 28xx (AT end device).
0 - 0xFF
CRE
CRE
0x2B 
(‘+’ ASCII)
1. Node types that support the command: C = Coordinator, R = Router, E = End Device
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XBee®/XBee‐PRO® ZB RF Modules
Sleep Commands
Sleep Commands
Node
Parameter Range
Type1
AT
Name and Description
Command
Default
SM
Sleep Mode Sets the sleep mode on the RF module. An XBee loaded with router
firmware can be configured as either a router (SM set to 0) or an end device (SM > 0).
RE
Changing a device from a router to an end device (or vice versa) forces the device to
leave the network and attempt to join as the new device type when changes are applied.
0-Sleep disabled (router)
0 - Router
1-Pin sleep enabled
4 - End
4-Cyclic sleep enabled
Device
5 - Cyclic sleep, pin wake
SN
Number of Sleep Periods. Sets the number of sleep periods to not assert the On/Sleep
pin on wakeup if no RF data is waiting for the end device. This command allows a host CRE
application to sleep for an extended time if no RF data is present
1 - 0xFFFF
SP
Sleep Period. This value determines how long the end device will sleep at a time, up to
28 seconds. (The sleep time can effectively be extended past 28 seconds using the SN
command.) On the parent, this value determines how long the parent will buffer a
CRE
message for the sleeping end device. It should be set at least equal to the longest SP
time of any child end device.
0x20 - 0xAF0 x 10ms
(Quarter second
resolution)
0x20
ST
Time Before Sleep Sets the time before sleep timer on an end device.The timer is reset
each time serial or RF data is received. Once the timer expires, an end device may enter E
low power operation. Applicable for cyclic sleep end devices only.
1 - 0xFFFE (x 1ms)
0x1388 (5
seconds)
SO
Command
Sleep Options. Configure options for sleep. Unused option bits should be set to 0.
Sleep options include:
0x02 - Always wake for ST time
0x04 - Sleep entire SN * SP time
0x06 - Enabled extended sleep and wake for ST time
Sleep options should not be used for most applications. See chapter 6 for more
information.
0 - 0xFF
WH
Wake Host. Set/Read the wake host timer value. If the wake host timer is set to a nonzero value, this timer specifies a time (in millisecond units) that the device should allow
after waking from sleep before sending data out the UART or transmitting an IO sample.
If serial characters are received, the WH timer is stopped immediately.
SI
Sleep Immediately. See Execution Commands table below..
PO
Polling Rate. Set/Read the end device poll rate. Setting this to 0 (default) enables
polling at 100 ms (default rate). Adaptive polling may allow the end device to poll more
rapidly for a short time when receiving RF data.
0 - 0xFFFF (x 1ms)
0 - 0x3E8
0x00 (100
msec)
Execution Commands
Where most AT commands set or query register values, execution commands cause an action to
be executed on the module. Execution commands are executed immediately and do not require
changes to be applied.
Execution Commands
AT
Name and Description
Command
Node Type1
Parameter Range Default
AC
Apply Changes. Applies changes to all command registers causing queued command
register values to be applied. For example, changing the serial interface rate with the BD
CRE
command will not change the UART interface rate until changes are applied with the AC
command. The CN command and 0x08 API command frame also apply changes.
WR
Write. Write parameter values to non-volatile memory so that parameter modifications
persist through subsequent resets.
CRE
Note: Once WR is issued, no additional characters should be sent to the module until
after the "OK\r" response is received. The WR command should be used sparingly. The
EM250 supports a limited number of write cycles.“
--
--
RE
Restore Defaults. Restore module parameters to factory defaults.
CRE
--
--
FR
Software Reset. Reset module. Responds immediately with an OK status, and then
performs a software reset about 2 seconds later.
CRE
--
--
NR
Network Reset. Reset network layer parameters on one or more modules within a PAN.
Responds immediately with an “OK” then causes a network restart. All network
configuration and routing information is consequently lost.
If NR = 0: Resets network layer parameters on the node issuing the command.
If NR = 1: Sends broadcast transmission to reset network layer parameters on all nodes
in the PAN.
CRE
0-1
--
SI
Sleep Immediately. Cause a cyclic sleep module to sleep immediately rather than wait
for the ST timer to expire.
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XBee®/XBee‐PRO® ZB RF Modules
Execution Commands
AT
Name and Description
Command
Node Type1
Parameter Range Default
CB
Commissioning Pushbutton. This command can be used to simulate commissioning
button presses in software. The parameter value should be set to the number of button
presses to be simulated. For example, sending the ATCB1 command will execute the
action associated with 1 commissioning button press.
CRE
Note: Setting CB=2 will send out the new value of NJ unless NJ has been set to either 0
or 255 (joining permanently disabled or permanently enabled respectively). In these two
cases, setting CB=2 enables joining for one minute. Joining will be disabled after the
minute expires.
ND
Node Discover. Discovers and reports all RF modules found. The following information
is reported for each module discovered.
MY
SH
SL
NI (Variable length)
PARENT_NETWORK ADDRESS (2 Bytes)
DEVICE_TYPE (1 Byte: 0=Coord, 1=Router, 2=End Device)
STATUS (1 Byte: Reserved)
PROFILE_ID (2 Bytes)
CRE
MANUFACTURER_ID (2 Bytes)

After (NT * 100) milliseconds, the command ends by returning a . ND also accepts
a Node Identifier (NI) as a parameter (optional). In this case, only a module that matches
the supplied identifier will respond.
If ND is sent through the API, each response is returned as a separate
AT_CMD_Response packet. The data consists of the above listed bytes without the
carriage return delimiters. The NI string will end in a "0x00" null character. The radius of
the ND command is set by the BH command.
optional 20-Byte 
NI or MY value
DN
Destination Node. Resolves an NI (Node Identifier) string to a physical address (casesensitive). The following events occur after the destination node is discovered:

1. DL & DH are set to the extended (64-bit) address of the module with the matching 
NI (Node Identifier) string.
2. OK (or ERROR)\r is returned. 
3. Command Mode is exited to allow immediate communication
CRE

1. The 16-bit network and 64-bit extended addresses are returned in an API 
Command Response frame.
If there is no response from a module within (NT * 100) milliseconds or a parameter is
not specified (left blank), the command is terminated and an “ERROR” message is
returned. In the case of an ERROR, Command Mode is not exited. The radius of the DN
command is set by the BH command.
up to 20-Byte printable
-ASCII string
IS
Force Sample Forces a read of all enabled digital and analog input lines.
--
--
1S
XBee Sensor Sample. Forces a sample to be taken on an XBee Sensor device. This
RE
command can only be issued to an XBee sensor device using an API remote command.
CRE
--
Node types that support the command: C = Coordinator, R = Router, E = End Device
© 2011 Digi International, Inc.
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11. Module Support
This chapter provides customization information for the XBee/XBee-PRO ZB modules. In addition to providing an
extremely flexible and powerful API, the XBee and XBee-PRO ZB modules are a robust development platform that have
passed FCC and ETSI testing. Developers can customize default parameters, or even write or load custom firmware for
Ember's EM250 chip.
Power up Module at 9600 Baud
If BREAK is asserted (DIN held low) at reset, the module will power on at a 9600 baud rate regardless of the
baud rate set in the firmware. This can be used to recover from an unsupported baud rate. If this is done with
AT firmware installed, the module will power on in AT command mode at 9600 baud and will remain at that baud
rate until command mode is exited. If API firmware is installed, the module will power on and send applicable
modem status API frames (reset notification, joined/started network, etc) out the UART at 9600 baud. It will
then be able to respond to API frames at 9600 baud until an API frame applies changes.
X-CTU Configuration Tool
Digi provides a Windows X-CTU configuration tool for configuring module parameters and updating firmware. The
XCTU has the capability to do the following:
•Discover all XBee devices in the network
•Update firmware on a local module (requires USB or serial connection)
•Read or write module configuration parameters on a local or remote device
•Save and load configuration profiles containing customized settings.
Contact Digi support for more information about the X-CTU.
Customizing XBee ZB Firmware
Once module parameters are tested in an application and finalized, Digi can manufacture modules with specific,
customer-defined configurations for a nominal fee. These custom configurations can lock in a firmware version or set
command values when the modules are manufactured, eliminating the need for customers to adjust module
parameters on arrival. Alternatively, Digi can program custom firmware, including Ember's EZSP UART image, into
the modules during manufacturing. Contact Digi to create a custom configuration.
Design Considerations for Digi Drop-In Networking
XBee/XBee-PRO embedded RF modules contain a variety of features that allow for interoperability with Digi's full line
of Drop-in Networking products. Interoperability with other "DIN" products can offer these advantages:
•Add IP-connectivity to your network via Cellular, Ethernet or WiFi with a ConnectPort X Gateway.
•Extend the range of your network with the XBee Wall Router.
•Make deployment easy by enabling the Commissioning Pushbutton (pin 20) and AssociateLED (pin 15) to operate with the Network Commissioning Tool software.
•Interface with standard RS-232, USB, Analog & Digital I/O, RS-485, and other industrial devices using XBee
Adapters.
•Monitor and manage your network securely from remote locations with iDigi Platform.
•We encourage you to contact our technical representatives for consideration, implementation, or design review
of your product for interoperability with Digi's Drop-in Networking solutions.
XBee Bootloader
XBee modules use a modified version of Ember’s bootloader. This bootloader version supports a custom entry
mechanism that uses module pins DIN (pin 3), DTR / SLEEP_RQ (pin 9), and RTS (pin 16). To invoke the bootloader,
do the following:
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XBee®/XBee‐PRO® ZB RF Modules
1. Set DTR / SLEEP_RQ low (TTL 0V) and RTS high.
2. Send a serial break to the DIN pin and power cycle or reset the module.
3. When the module powers up, DTR / SLEEP_RQ and DIN should be low (TTL 0V) and RTS should be high.
4. Terminate the serial break and send a carriage return at 115200bps to the module.
5. If successful, the module will send the Ember bootloader menu out the DOUT pin at 115200bps.
6. Commands can be sent to the bootloader at 115200bps.
Note: Hardware flow control should be disabled when entering and communicating with the EM250 bootloader.
Programming XBee Modules
Firmware on the XBee and XBee-PRO ZB modules can be updated through one of two means:
•Serially
•SIF header.
Each method is described below.
Where possible, configuration settings are retained regardless of firmware changes. This can lead to difficulties,
especially when changing firmware among variants of the same release with different default config settings. The
best practice after changing a firmware load is to do a RE (reset to factory defaults), explicitly set the configuration
registers to desired settings, and then do a WR (write config settings).
Serial Firmware Updates
Serial firmware updates make use of the XBee custom bootloader which ships in all units. This modified
bootloader is based on Ember's standalone bootloader, but with a modified entry mechanism. The modified
entry mechanism uses module pins 3, 9, and 16 (DIN, DTR, and RTS respectively).
The X-CTU program can update firmware serially on the XBee and XBee-PRO ZB modules. Contact Digi support
for details.
If an application requires custom firmware to update the XBee firmware serially, the following steps are
required.
Invoke XBee Bootloader
See the "XBee Bootloader" section above for steps to invoke the bootloader.
Send Firmware Image
After invoking the bootloader, the Ember bootloader will send the bootloader menu characters out the UART at
115200 bps. The application should do the following to upload a firmware image.
1. Look for the bootloader prompt "BL >" to ensure the bootloader is active
2. Send an ASCII "1" character to initiate a firmware update
3. After sending a "1", the EM250 waits for an XModem CRC upload of an .ebl image over the serial line at
115200 bps. The .ebl file must be sent to the EM250 in order.
If no serial transaction is initiated within a 60 second timeout period, the bootloader times out and returns to
the menu. If the upload is interrupted with a power cycle or reset event, the EM250 will detect an invalid
application image and enter bootloader mode. The entire ebl image should be uploaded again to recover. If an
error occurs while uploading, the EM250 bootloader returns an error code from the following table:
Hex Error Code
0x21
0x22
© 2011 Digi International, Inc.
Description
The bootloader encountered an error while
trying to parse the Start of Header (SOH)
character in the XModem frame.
The bootloader detected an invalid checksum
in the XModem frame.
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XBee®/XBee‐PRO® ZB RF Modules
Hex Error Code
Description
0x23
The bootloader encountered an error while
trying to parse the high byte of the CRC in the
XModem frame.
0x24
The bootloader encountered an error while
trying to parse the low byte of the CRC in the
XModem frame.
0x25
The bootloader encountered an error in the
sequence number of the current XModem
frame.
0x26
The frame that the bootloader was trying to
parse was deemed incomplete (some bytes
missing or lost).
0x27
The bootloader encountered a duplicate of the
previous XModem frame.
0x41
No .ebl header was received when expected.
0x42
Header failed CRC.
0x43
File failed CRC.
0x44
Unknown tag detected in .ebl image.
0x45
Invalid .ebl header signature.
0x46
Trying to flash odd number of bytes.
0x47
Indexed past end of block buffer.
0x48
Attempt to overwrite bootloader flash.
0x49
Attempt to overwrite SIMEE flash.
0x4A
Flash erase failed.
0x4B
Flash write failed.
0x4C
End tag CRC wrong length.
0x4D
Received data before query request/response
SIF Firmware Updates
The XBee/XBee-PRO modules have a 2x5 SIF header that can be used with Ember's InSight tools to upload
firmware onto the modules. These tools include a USB device (USBLink) and Ethernet-enabled InSight Adapters.
Contact Ember for details.
Warning: If programming firmware through the SIF interface, be aware that uploading firmware through the
SIF header can potentially erase the XBee bootloader. If this happens, serial firmware updates will not work.
(The pinout for the SIF headers are shown in chapter 1.)
Writing Custom Firmware
The XBee/XBee-PRO module can be used as a hardware development platform for the EM250. Custom firmware
images can be developed around the EmberZNet 2.5.x and 3.x mesh stacks (for the EM250) and uploaded to the
XBee.
Warning: If programming firmware through the SIF interface, be aware that uploading firmware through the SIF
header can potentially erase the XBee bootloader. If this happens, serial firmware updates will not work.
Regulatory Compliance
XBee modules are FCC and ETSI certified for operation on all 16 channels. The EM250 output power can be
configured up to 3dBm with boost mode enabled.
XBee-PRO modules are certified for operation on 14 of the 16 band channels (channels 11 - 24). The scan
channels mask of XBee-PRO devices must be set in the application to disable the upper two channels (e.g.
0x01FFF800). The XBee-PRO contains power compensation circuitry to adjust the output power near 18dBm or
10dBm depending on the part number. For best results, the EM250 should be configured with an output power
level of 0dBm (or -2dBm if boost mode is enabled). The end product is responsible to adhere to these
requirements.
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XBee®/XBee‐PRO® ZB RF Modules
Enabling GPIO 1 and 2
Most of the remaining sections in this chapter describe how to configure GPIO 1 and 2 to function correctly in
custom applications that run on the XBee and XBee-PRO modules. In order for GPIO pins 1 and 2 to be
configurable, the application must set the GPIO_CFG register to enable GPIO 1 and 2. Bits 4 - 7 in the
GPIO_CFG register control the functionality of various GPIO lines. The following table lists values for these bits
that enable GPIO 1 and 2. Other functionality is affected by these settings. See the EM250 datasheet from
Ember for a complete listing of functionality.
GPIO_CFG[7:4]Enabled Functionality Enabled Functionality
0000
GPIO 0, 1, 2, 3, 9, 10, 11, 12
0111
0111GPIO 0, 1, 2, 3, 12
1010
GPIO 0, 1, 2, 3
1101
GPIO 0, 1, 2, 3, 11, 12
Example 1
The following code enables GPIO 0, 1, 2, 3, 9, 10, 11, and 12 and maintains all other GPIO_CFG bits.
int16u x;
x = GPIO_CFG;
x &= (0xFF0F); // Clear bits 4 - 7
GPIO_CFG = x;
Example 2
The following code enables GPIO 0, 1, 2, 3, and 12 and maintains all other GPIO_CFG bits.
int16u x;
x = GPIO_CFG;
x &= (0xFF0F); // Clear bits 4 - 7
x |= 0x0070;
// Set bits 4 - 7 to 0111 as shown in the table above.
GPIO_CFG = x;
Detecting XBee vs. XBee-PRO
For some applications, it may be necessary to determine if the code is running on an XBee or an XBee-PRO
device. The GPIO1 pin on the EM250 is used to identify the module type (see table 1-03 in chapter 1). GPIO1 is
connected to ground on the XBee module. The following code could be used to determine if a module is an XBee
or XBee-PRO:
GPIO_DIRCLRL = GPIO(1);// Set GPIO1 as an input
GPIO_PUL |= GPIO(1);// Enable GPIO1 pullup resistor
ModuleIsXBeePro = (GPIO_INL & GPIO(1));//ModuleIsXBeePro > 0 if XBee-PRO, =0 if non-PRO.
Ensuring Optimal Output Power
XBee modules manufactured before February 2008 had an incorrect configuration setting that caused the
default output power mode to be set incorrectly. Digi's ZB and ZNet firmware compensate for this by setting the
output power mode in the application firmware.
Custom applications should call the emberSetTxPowerMode() function to set the output power mode as shown
below:
XBee Applications
emberSetTxPowerMode(EMBER_TX_POWER_MODE_DEFAULT); or
emberSetTxPowerMode(EMBER_TX_POWER_MODE_BOOST);
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XBee®/XBee‐PRO® ZB RF Modules
XBee-PRO Applications:
emberSetTxPowerMode(EMBER_TX_POWER_MODE_ALTERNATE); or
emberSetTxPowerMode(EMBER_TX_POWER_MODE_BOOST_AND_ALTERNATE);
XBee-PRO modules must also set a couple of IO lines to enable output power compensation. This is shown
below. Once the IO lines are initialized (after powerup), the XBee will enable the power amplifier and LNA
as needed.
On Powerup:
/* GPIO 2 should be set low for at least 10 milliseconds when coming up from power cycle. */
GPIO_DIRSETL = GPIO(2);// Set GPIO 2 as an output
GPIO_CLRL = GPIO(2); // Drive GPIO 2 low
/* After at least 10ms, GPIO 2 should be set high to power the output power compensation circuitry.
At the same time GPIO 1 should be configured as an output and set low to enable the output power
compensation circuitry. */
GPIO_DIRSETL = GPIO(1) | GPIO(2);// Set GPIO 1,2 as outputs
GPIO_CLRL = GPIO(1); // Drive GPIO 1 low
GPIO_SETL = GPIO(2); // Drive GPIO 2 high
Improving Low Power Current Consumption
To improve low power current consumption, the XBee should set a couple of unused IO lines as output low. This can
be done during application initialization as shown below.
XBee (non-PRO) Initialization:
/* GPIO 1 and 2 are not used in the XBee (non-PRO) and should be set as outputs and driven low to reduce
current draw. */
GPIO_DIRSETL = GPIO(1) | GPIO(2);// Set GPIO 1,2 as outputs
GPIO_CLRL = GPIO(1) | GPIO(2);// Set GPIO 1,2 low
XBee-PRO modules should disable the power compensation circuitry when sleeping to reduce current draw. This
is shown below.
When sleeping (end devices):
/* The power compensation shutdown line on XBee-PRO modules (GPIO 1) should be set high when entering
sleep to reduce current consumption. */
GPIO_SETL = GPIO(1);
When waking from sleep (end devices):
/* The power compensation shutdown line on XBee-PRO (GPIO 1) should be set low to enable the
power compensation circuitry and LNA. */
GPIO_CLRL = GPIO(1);
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
© 2011 Digi International, Inc.
143
Appendix A: Definitions
Definitions
ZigBee Node Types
Coordinator
A node that has the unique function of forming a network. The coordinator is responsible for establishing the operating channel and PAN
ID for an entire network. Once established, the coordinator can form
a network by allowing routers and end devices to join to it. Once the
network is formed, the coordinator functions like a router (it can participate in routing packets and be a source or destination for data
packets).
------
One coordinator per PAN
Establishes/Organizes PAN
Can route data packets to/from other nodes
Can be a data packet source and destination
Mains-powered
Refer to the XBee coordinator section for more information.
Router
A node that creates/maintains network information and uses this
information to determine the best route for a data packet. A router
must join a network before it can allow other routers and end
devices to join to it.
A router can participate in routing packets and is intended to be a
mains-powered node.
-----
Several routers can operate in one PAN
Can route data packets to/from other nodes
Can be a data packet source and destination
Mains-powered
Refer to the XBee router section for more information.
End device
End devices must always interact with their parent to receive or
transmit data. (See ‘joining definition.) They are intended to sleep
periodically and therefore have no routing capacity.
An end device can be a source or destination for data packets but
cannot route packets. End devices can be battery-powered and offer
low-power operation.
-----
© 2011 Digi International, Inc.
Several end devices can operate in one PAN
Can be a data packet source and destination 
All messages are relayed through a coordinator or router
Lower power modes
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XBee®/XBee‐PRO® ZB RF Modules
ZigBee Protocol
PAN
Personal Area Network - A data communication network that
includes a coordinator and one or more routers/end devices.
Joining
The process of a node becoming part of a ZigBee PAN. A node
becomes part of a network by joining to a coordinator or a router
(that has previously joined to the network). During the process of
joining, the node that allowed joining (the parent) assigns a 16-bit
address to the joining node (the child).
Network Address
The 16-bit address assigned to a node after it has joined to another
node. The coordinator always has a network address of 0.
Operating Channel
The frequency selected for data communications between nodes. The
operating channel is selected by the coordinator on power-up.
Energy Scan
A scan of RF channels that detects the amount of energy present on
the selected channels. The coordinator uses the energy scan to
determine the operating channel.
Route Request
Broadcast transmission sent by a coordinator or router throughout
the network in attempt to establish a route to a destination node.
Route Reply
Unicast transmission sent back to the originator of the route request.
It is initiated by a node when it receives a route request packet and
its address matches the Destination Address in the route request
packet.
Route Discovery
The process of establishing a route to a destination node when one
does not exist in the Routing Table. It is based on the AODV (Ad-hoc
On-demand Distance Vector routing) protocol.
ZigBee Stack
ZigBee is a published specification set of high-level communication
protocols for use with small, low-power modules. The ZigBee stack
provides a layer of network functionality on top of the 802.15.4 specification.
For example, the mesh and routing capabilities available to ZigBee
solutions are absent in the 802.15.4 protocol.
© 2011 Digi International, Inc.
145
Appendix B: Agency Certifications
United States FCC
The XBee RF Module complies with Part 15 of the FCC rules and regulations. Compliance with the labeling
requirements, FCC notices and antenna usage guidelines is required.
To fulfill FCC Certification, the OEM must comply with the following regulations:
1.The system integrator must ensure that the text on the external label provided with this
device is placed on the outside of the final product.
2.XBee RF Module may only be used with antennas that have been tested and approved for use
with this module [refer to the antenna tables in this section].
OEM Labeling Requirements
WARNING: The Original Equipment Manufacturer (OEM) must ensure that FCC labeling
requirements are met. This includes a clearly visible label on the outside of the final product
enclosure that displays the contents shown in the figure below.
Required FCC Label for OEM products containing the XBee RF Module
Contains FCC ID: OUR-XBEE2*
The enclosed device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions: (i.) this device may not cause harmful interference and (ii.) this device must accept any
interference received, including interference that may cause undesired operation.
Required FCC Label for OEM products containing the XBee PRO (S2) RF Module
Contains FCC ID:MCQ-XBEEPRO2*
The enclosed device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions: (i.) this device may not cause harmful interference and (ii.) this device must accept any
interference received, including interference that may cause undesired operation.
Required FCC Label for OEM products containing the XBee PRO (S2B) RF Module
Contains FCC ID:MCQ-PROS2B*
The enclosed device complies with Part 15 of the FCC Rules. Operation is subject to the following two
conditions: (i.) this device may not cause harmful interference and (ii.) this device must accept any
interference received, including interference that may cause undesired operation.
FCC Notices
IMPORTANT: The XBee and XBee PRO RF Module have been certified by the FCC for use with other
products without any further certification (as per FCC section 2.1091). Modifications not expressly
approved by Digi could void the user's authority to operate the equipment.
IMPORTANT: OEMs must test final product to comply with unintentional radiators (FCC section 15.107 &
15.109) before declaring compliance of their final product to Part 15 of the FCC Rules.
IMPORTANT: The RF module has been certified for remote and base radio applications. If the module will
be used for portable applications, the device must undergo SAR testing.
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to
Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment generates, uses and can radiate radio frequency
energy and, if not installed and used in accordance with the instructions, may cause harmful interference to
radio communications. However, there is no guarantee that interference will not occur in a particular
installation.
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
If this equipment does cause harmful interference to radio or television reception, which can be determined
by turning the equipment off and on, the user is encouraged to try to correct the interference by one or
more of the following measures: Re-orient or relocate the receiving antenna, Increase the separation
between the equipment and receiver, Connect equipment and receiver to outlets on different circuits, or
Consult the dealer or an experienced radio/TV technician for help.
FCC-Approved Antennas (2.4 GHz)
The XBee and XBee-PRO RF Module can be installed utilizing antennas and cables constructed with
standard connectors (Type-N, SMA, TNC, etc.) if the installation is performed professionally and according
to FCC guidelines. For installations not performed by a professional, non-standard connectors (RPSMA,
RPTNC, etc.) must be used.
The modules are FCC approved for fixed base station and mobile applications for the channels indicated in
the tables below. If the antenna is mounted at least 20cm (8 in.) from nearby persons, the application is
considered a mobile application. Antennas not listed in the table must be tested to comply with FCC Section
15.203 (Unique Antenna Connectors) and Section 15.247 (Emissions).
XBee RF Modules: XBee RF Modules have been tested and approved for use with all the antennas listed in
the tables below. (Cable-loss IS required when using gain antennas as shown below.)
The antennas in the tables below have been approved for use with this module. Digi does not carry all of
these antenna variants. Contact Digi Sales for available antennas.
Antennas approved for use with the XBee®/XBee‐PRO® ZB RF Modules (Cable‐loss is not required.)
OMNI-DIRECTIONAL ANTENNAS for All Available Channels
Minimum Cable
Loss/Power
Reduction/
Attenuation
Required
Type (Description)
Gain
Application*
Min
Separation
A24-HASM-450
Dipole (Half-wave articulated RPSMA - 4.5”)
2.1 dBi
Fixed/Mobile
20 cm
N/A
A24-HABSM
Dipole (Articulated RPSMA)
2.1 dBi
Fixed
20 cm
N/A
A24-HABUF-P5I
Dipole (Half-wave articulated bulkhead mount U.FL. w/ 5”
pigtail)
2.1 dBi
Fixed
20 cm
N/A
A24-HASM-525
Dipole (Half-wave articulated RPSMA - 5.25")
2.1 dBi
Fixed/Mobile
20 cm
N/A
A24-QI
Monopole (Integrated whip)
1.5 dBi
Fixed
20 cm
N/A
29000294
Integral PCB antenna (S2B only)
-0.5 dBi
Fixed/Mobile
20 cm
N/A
29000095
Dipole (Half-wave articulated RPSMA - 4.5”)
2.1 dBi
Fixed/Mobile
20 cm
N/A
29000430
Integral PCB Antenna (S2 only)
-0.5 dBi
Fixed/Mobile
20 cm
N/A
Part Number
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Antennas approved for use with the XBee RF Module
YAGI CLASS ANTENNAS for Channels 11 - 26
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-Y6NF
A24-Y7NF
A24-Y9NF
A24-Y10NF
A24-Y12NF
A24-Y13NF
A24-Y15NF
A24-Y16NF
A24-Y16RM
A24-Y18NF
Yagi (6-element)
Yagi (7-element)
Yagi (9-element)
Yagi (10-element)
Yagi (12-element)
Yagi (13-element)
Yagi (15-element)
Yagi (16-element)
Yagi (16-element, RPSMA connector)
Yagi (18-element)
8.8 dBi
9.0 dBi
10.0 dBi
11.0 dBi
12.0 dBi
12.0 dBi
12.5 dBi
13.5 dBi
13.5 dBi
15.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
2m
2m
2m
7.8 dB
8 dB
9 dB
10 dB
11 d
11 dB
11.5 dB
12.5 dB
12.5 dB
14 dB
PANEL CLASS ANTENNAS for Channels 11 - 26
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-P8SF
A24-P8NF
A24-P13NF
A24-P14NF
A24-P15NF
A24-P16NF
A24-P19NF
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
8.5 dBi
8.5 dBi
13.0 dBi
14.0 dBi
15.0 dBi
16.0 dBi
19.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
8.2 dB
8.2 dB
12.7 dB
13.7 dB
14.7 dB
15.7 dB
18.7 dB
OMNI-DIRECTIONAL ANTENNAS for Channels 11 - 26
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-C1
Surface Mount Integral Chip
-1.5 dBi
Fixed/Mobile
20 cm
N/A
N/A
A24-F2NF
Omni-directional (Fiberglass base station)
2.1 dBi
Fixed/Mobile
20 cm
A24-F3NF
Omni-directional (Fiberglass base station)
3.0 dBi
Fixed/Mobile
20 cm
A24-F5NF
Omni-directional (Fiberglass base station)
5.0 dBi
Fixed/Mobile
20 cm
A24-F8NF
Omni-directional (Fiberglass base station)
8.0 dBi
Fixed
2m
5.3 dB
A24-F9NF
Omni-directional (Fiberglass base station)
9.5 dBi
Fixed
2m
6.8 dB
A24-F10NF
Omni-directional (Fiberglass base station)
10.0 dBi
Fixed
2m
7.3 dB
A24-F12NF
Omni-directional (Fiberglass base station)
12.0 dBi
Fixed
2m
9.3 dB
A24-F15NF
Omni-directional (Fiberglass base station)
15.0 dBi
Fixed
2m
12.3 dB
A24-W7NF
Omni-directional (Base station)
7.2 dBi
Fixed
2m
4.5 dB
A24-M7NF
Omni-directional (Mag-mount base station)
7.2 dBi
Fixed
2m
4.5 dB
© 2011 Digi International, Inc.
0.3 dB
2.3 dB
148
XBee®/XBee‐PRO® ZB RF Modules
Antennas approved for use with the XBee‐PRO (S2) RF Module
YAGI CLASS ANTENNAS for Channels 11 - 24
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-Y6NF
A24-Y7NF
A24-Y9NF
A24-Y10NF
A24-Y12NF
A24-Y13NF
A24-Y15NF
A24-Y16NF
A24-Y16RM
A24-Y18NF
Yagi (6-element)
Yagi (7-element)
Yagi (9-element)
Yagi (10-element)
Yagi (12-element)
Yagi (13-element)
Yagi (15-element)
Yagi (16-element)
Yagi (16-element, RPSMA connector)
Yagi (18-element)
8.8 dBi
9.0 dBi
10.0 dBi
11.0 dBi
12.0 dBi
12.0 dBi
12.5 dBi
13.5 dBi
13.5 dBi
15.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
2m
2m
2m
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.5 dB
PANEL CLASS ANTENNAS for Channels 11 - 24
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-P8SF
A24-P8NF
A24-P13NF
A24-P14NF
A24-P15NF
A24-P16NF
A24-P19NF
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
8.5 dBi
8.5 dBi
13.0 dBi
14.0 dBi
15.0 dBi
16.0 dBi
19.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
N/A
N/A
N/A
N/A
N/A
N/A
2.5 dB
OMNI-DIRECTIONAL ANTENNAS for Channels 11 - 24
Part Number
Type (Description)
Gain
Application*
Min. Separation Cable-loss
Required
A24-C1
A24-F2NF
A24-F3NF
A24-F5NF
A24-F8NF
A24-F9NF
A24-F10NF
A24-F12NF
A24-F15NF
A24-W7NF
A24-M7NF
Surface Mount integral chip
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Base station)
Omni-directional (Mag-mount base station)
-1.5dBi
2.1 dBi
3.0 dBi
5.0 dBi
8.0 dBi
9.5 dBi
10.0 dBi
12.0 dBi
15.0 dBi
7.2 dBi
7.2 dBi
Fixed/Mobile
Fixed/Mobile
Fixed/Mobile
Fixed/Mobile
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
20 cm
20 cm
20 cm
20 cm
2m
2m
2m
2m
2m
2m
2m
© 2011 Digi International, Inc.
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.5 dB
N/A
N/A
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XBee®/XBee‐PRO® ZB RF Modules
Antennas approved for use with the XBee‐PRO (S2B) RF Module
YAGI CLASS ANTENNAS for Channels 11 to 24
Part Number Type (Description)
Gain
Application*
Min. Separation
Minimum Cable Loss/
Power Reduction/
Attenuation Required
for 18dBm Output
A24-Y6NF
A24-Y7NF
A24-Y9NF
A24-Y10NF
A24-Y12NF
A24-Y13NF
A24-Y15NF
A24-Y16NF
A24-Y16RM
A24-Y18NF
8.8 dBi
9.0 dBi
10.0 dBi
11.0 dBi
12.0 dBi
12.0 dBi
12.5 dBi
13.5 dBi
13.5 dBi
15.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
2m
2m
2m
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Part Number Type (Description)
Gain
Application*
Min. Separation
Minimum Cable Loss/
Power Reduction/
Attenuation Required
for 18dBm Output
A24-P8SF
A24-P8NF
A24-P13NF
A24-P14NF
A24-P15NF
A24-P16NF
A24-P19NF
8.5 dBi
8.5 dBi
13.0 dBi
14.0 dBi
15.0 dBi
16.0 dBi
19.0 dBi
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
2m
2m
2m
N/A
N/A
N/A
0.8 dB
1.8 dB
2.8 dB
5.8 dB
Yagi (6-element)
Yagi (7-element)
Yagi (9-element)
Yagi (10-element)
Yagi (12-element)
Yagi (13-element)
Yagi (15-element)
Yagi (16-element)
Yagi (16-element, RPSMA connector)
Yagi (18-element)
PANEL CLASS ANTENNAS for Channels 11 to 24
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
Flat Panel
OMNI-DIRECTIONAL ANTENNAS for Channels 11 to 24
Part Number Type (Description)
Gain
Application*
Min. Separation
Minimum Cable Loss/
Power Reduction/
Attenuation Required
for 18dBm Output
A24-F9NF
A24-F10NF
A24-F12NF
A24-F15NF
9.5 dBi
10.0 dBi
12.0 dBi
15.0 dBi
Fixed
Fixed
Fixed
Fixed
2m
2m
2m
2m
N/A
N/A
N/A
N/A
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
OMNI-DIRECTIONAL ANTENNAS for Channels 11 to 25
Part Number Type (Description)
Gain
Application*
Min. Separation
Minimum Cable Loss/
Power Reduction/
Attenuation Required
for 18dBm Output
A24-F2NF
A24-F3NF
A24-F5NF
A24-F8NF
A24-W7NF
A24-M7NF
2.1 dBi
3.0 dBi
5.0 dBi
8.0 dBi
7.2 dBi
7.2 dBi
Fixed/Mobile
Fixed/Mobile
Fixed/Mobile
Fixed
Fixed
Fixed
20 cm
20 cm
20 cm
2m
2m
2m
N/A
N/A
N/A
N/A
N/A
N/A
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Fiberglass base station)
Omni-directional (Base station)
Omni-directional (Mag-mount base station)
* If using the RF module in a portable application (for example - if the module is used in a handheld device and the antenna is less than 20cm from
the human body when the device is in operation): The integrator is responsible for passing additional SAR (Specific Absorption Rate) testing based on
FCC rules 2.1091 and FCC Guidelines for Human Exposure to Radio Frequency Electromagnetic Fields, OET Bulletin and Supplement C. The testing
results will be submitted to the FCC for approval prior to selling the integrated unit. The required SAR testing measures emissions from the module and
how they affect the person.
RF Exposure
WARNING: To satisfy FCC RF exposure requirements for mobile transmitting devices, a separation distance of
20 cm or more should be maintained between the antenna of this device and persons during device operation.
To ensure compliance, operations at closer than this distance are not recommended. The antenna used for this
transmitter must not be co-located in conjunction with any other antenna or transmitter.
The preceding statement must be included as a CAUTION statement in OEM product manuals in order to alert users of FCC RF Exposure compliance.
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
Europe (ETSI)
The XBee RF Modules have been certified for use in several European countries. For a complete list, refer to
www.digi.com
If the XBee RF Modules are incorporated into a product, the manufacturer must ensure compliance of the
final product to the European harmonized EMC and low-voltage/safety standards. A Declaration of
Conformity must be issued for each of these standards and kept on file as described in Annex II of the
R&TTE Directive.
Furthermore, the manufacturer must maintain a copy of the XBee user manual documentation and ensure
the final product does not exceed the specified power ratings, antenna specifications, and/or installation
requirements as specified in the user manual. If any of these specifications are exceeded in the final
product, a submission must be made to a notified body for compliance testing to all required standards.
OEM Labeling Requirements
The 'CE' marking must be affixed to a visible location on the OEM product.
CE Labeling Requirements
The CE mark shall consist of the initials "CE" taking the following form:
•If the CE marking is reduced or enlarged, the proportions given in the above graduated drawing must
be respected.
•The CE marking must have a height of at least 5mm except where this is not possible on account of
the nature of the apparatus.
•The CE marking must be affixed visibly, legibly, and indelibly.
Restrictions
France: Outdoor use limited to 10 mW EIRP within the band 2454-2483.5 MHz.
Norway: Norway prohibits operation near Ny-Alesund in Svalbard. More information can be found at the
Norway Posts and Telecommunications site (www.npt.no).
Declarations of Conformity
Digi has issued Declarations of Conformity for the XBee RF Modules concerning emissions, EMC and safety.
Files can be obtained by contacting Digi Support.
Important Note:
Digi does not list the entire set of standards that must be met for each country. Digi customers assume full
responsibility for learning and meeting the required guidelines for each country in their distribution market.
For more information relating to European compliance of an OEM product incorporating the XBee RF
Module, contact Digi, or refer to the following web sites:
CEPT ERC 70-03E - Technical Requirements, European restrictions and general requirements: Available at
www.ero.dk/.
R&TTE Directive - Equipment requirements, placement on market: Available at www.ero.dk/.
Approved Antennas
XBee RF Module
The following antennas are approved for use with the embedded XBee RF Module:
- Dipole (2.1 dBi, Omni-directional, Articulated RPSMA, Digi part number A24-HABSM)
- Chip Antenna (-1.5 dBi)
- Attached Monopole Whip (1.5 dBi)
© 2011 Digi International, Inc.
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XBee®/XBee‐PRO® ZB RF Modules
- Integral PCB Antenna (-0.5 dBi)
XBee-PRO (S2) RF Module
The following antennas are approved for use with the embedded XBee-PRO S2 RF Module:
- Dipole (2.1 dBi, Omni-directional, Articulated RPSMA, Digi part number A24-HABSM)
- Chip Antenna (-1.5 dBi)
- Attached Monopole Whip (1.5 dBi)
- Integral PCB Antenna (-0.5 dBi).
XBee-PRO (S2B) RF Module
The following antennas are approved for use with the embedded XBee-PRO RF S2B Module:
- Dipole (2.1 dBi, Omni-directional, Articulated RPSMA, Digi part number A24-HABSM)
- PCB Embedded Trace Antenna (-0.5dBi)
- Attached Monopole Whip (1.5 dBi).
Canada (IC)
This device complies with Industry Canada licence-exempt RSS standard(s). Operation is subject to the
following two conditions: (1) this device may not cause interference, and (2) this device must accept any
interference, including interference that may cause undesired operation of the device.
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de
licence. L'exploitation est autorisée aux deux conditions suivantes : (1) l'appareil ne doit pas produire de
brouillage, et (2) l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le
brouillage est susceptible d'en compromettre le fonctionnement.
Labeling Requirements
Labeling requirements for Industry Canada are similar to those of the FCC. A clearly visible label on the
outside of the final product enclosure must display the following text:
Contains Model XBee Radio, IC: 4214A-XBEE2
The integrator is responsible for its product to comply with IC ICES-003 & FCC Part 15, Sub. B Unintentional Radiators. ICES-003 is the same as FCC Part 15 Sub. B and Industry Canada accepts FCC
test report or CISPR 22 test report for compliance with ICES-003.
If it contains an XBee-PRO (S2) RF Module, the clearly visible label on the outside of the final product
enclosure must display the following text:
Contains Model XBee PRO Radio, IC: 1846A-XBEEPRO2
If it contains an XBee-PRO (S2B) RF Module, the clearly visible label on the outside of the final product
enclosure must display the following text:
Contains Model XBee PRO S2B Radio, IC: 1846A-PROS2B
The integrator is responsible for its product to comply with IC ICES-003 & FCC Part 15, Sub. B Unintentional Radiators. ICES-003 is the same as FCC Part 15 Sub. B and Industry Canada accepts FCC
test report or CISPR 22 test report for compliance with ICES-003.
Transmitters for Detachable Antennas
This radio transmitter has been approved by Industry Canada to operate with the antenna types listed in
the table above with the maximum permissible gain and required antenna impedance for each antenna
type indicated. Antenna types not included in this list, having a gain greater than the maximum gain
indicated for that type, are strictly prohibited for use with this device. The required antenna impedance is
50 ohms.
Le présent émetteur radio a été approuvé par Industrie Canada pour fonctionner avec les types d'antenne
énumérés ci-dessous et ayant un gain admissible maximal et l'impédance requise pour chaque type
d'antenne. Les types d'antenne non inclus dans cette liste, ou dont le gain est supérieur au gain maximal
indiqué, sont strictement interdits pour l'exploitation de l'émetteur.
© 2011 Digi International, Inc.
152
XBee®/XBee‐PRO® ZB RF Modules
Detachable Antenna
Under Industry Canada regulations, this radio transmitter may only operate using an antenna of a type and
maximum (or lesser) gain approved for the transmitter by Industry Canada. To reduce potential radio
interference to other users, the antenna type and its gain should be so chosen that the equivalent
isotropically radiated power (e.i.r.p.) is not more than that necessary for successful communication.
Conformément à la réglementation d'Industrie Canada, le présent émetteur radio peut fonctionner avec
une antenne d'un type et d'un gain maximal (ou inférieur) approuvé pour l'émetteur par Industrie Canada.
Dans le but de réduire les risques de brouillage radioélectrique à l'intention des autres utilisateurs, il faut
choisir le type d'antenne et son gain de sorte que la puissance isotrope rayonnée équivalente (p.i.r.e.) ne
dépasse pas l'intensité nécessaire àl'établissement d'une communication satisfaisante.
Australia (C-Tick)
These modules comply with requirements to be used in end products in Australia. All products with EMC
and radio communications must have a registered C-Tick mark. Registration to use the compliance mark
will only be accepted from Australian manufacturers or importers, or their agent, in Australia.
In order to have a C-Tick mark on an end product, a company must comply with a or b below.
a. have a company presence in Australia.
b. have a company/distributor/agent in Australia that will sponsor the importing of the end 
product.
Contact Digi for questions related to locating a contact in Australia.
© 2011 Digi International, Inc.
153
Appendix C: Migrating from ZNet 2.5 to XBee
ZB
The following paragraph contains the significant differences in XBee ZB compared to its predecessor, ZNet 2.5.
•Command Set
•Firmware Versions
•New Features.
Command Set
The following ZNet 2.5 commands have changed for XBee ZB:
•ZA - Set / read the ZigBee Addressing enable command. This command was required in ZNet 2.5 to enable
application level addressing commands SE, DE, CI. XBee ZB does not support ZA. The SE, DE, and CI values
always determine the application level addressing values.
•AI - Read the association status. AI now includes several new values.
New Features
ZB offers many new and improved features over ZNet 2.5, including:
•Data transmissions are directly resolved to APS unicasts. This provides the ability to send and receive ZDO commands.
•NH command configures the unicast transmission timeout. This command can extend the number of unicast
hops dramatically over the 6-8 hop limit that existed in ZNet 2.5.
•ZS command allows ZigBee stack profile to be set as required.
•Routers and coordinators can expire end device children from their child tables if the end device has not polled
within a settable timeout.
•Routers and coordinators can expire end device children from their child tables if the end device has not polled
within a settable timeout.
© 2011 Digi International, Inc.
154
Appendix D:Additional Information
1-Year Warranty
XBee RF Modules from Digi International, Inc. (the "Product") are warranted against defects in materials and
workmanship under normal use, for a period of 1-year from the date of purchase. In the event of a product
failure due to materials or workmanship, Digi will repair or replace the defective product. For warranty service,
return the defective product to Digi International, shipping prepaid, for prompt repair or replacement.
The foregoing sets forth the full extent of Digi International's warranties regarding the Product. Repair or
replacement at Digi International's option is the exclusive remedy. THIS WARRANTY IS GIVEN IN LIEU OF ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, AND DIGI SPECIFICALLY DISCLAIMS ALL WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL DIGI, ITS SUPPLIERS OR
LICENSORS BE LIABLE FOR DAMAGES IN EXCESS OF THE PURCHASE PRICE OF THE PRODUCT, FOR ANY LOSS
OF USE, LOSS OF TIME, INCONVENIENCE, COMMERCIAL LOSS, LOST PROFITS OR SAVINGS, OR OTHER
INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
PRODUCT, TO THE FULL EXTENT SUCH MAY BE DISCLAIMED BY LAW. SOME STATES DO NOT ALLOW THE
EXCLUSION OR LIMITATION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES. THEREFORE, THE FOREGOING
EXCLUSIONS MAY NOT APPLY IN ALL CASES. This warranty provides specific legal rights. Other rights which
vary from state to state may also apply.
© 2011 Digi International, Inc.
155

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