User's Manual
Table Of Contents
- 1. Overview
- 2. RF Module Operation
- 3. XBee ZigBee Networks
- Introduction to ZigBee
- ZigBee Stack Layers
- Networking Concepts
- ZigBee Application Layers: In Depth
- Coordinator Operation
- Router Operation
- End Device Operation
- Channel Scanning
- 4. Data Transmission, Addressing, and Routing
- 5. Security
- 6. Network Commissioning and Diagnostics
- 7. Managing End Devices
- 8. XBee Analog and Digital IO Lines
- 9. API Operation
- API Frame Specifications
- API UART Exchanges
- Supporting the API
- API Frames
- AT Command
- AT Command - Queue Parameter Value
- ZigBee Transmit Request
- Explicit Addressing ZigBee Command Frame
- Remote AT Command Request
- Create Source Route
- AT Command Response
- Modem Status
- ZigBee Transmit Status
- ZigBee Receive Packet
- ZigBee Explicit Rx Indicator
- ZigBee IO Data Sample Rx Indicator
- XBee Sensor Read Indicator
- Node Identification Indicator
- Remote Command Response
- Over-the-Air Firmware Update Status
- Route Record Indicator
- Many-to-One Route Request Indicator
- Sending ZigBee Device Objects (ZDO) Commands with the API
- Sending ZigBee Cluster Library (ZCL) Commands with the API
- Sending Public Profile Commands with the API
- 10. XBee Command Reference Tables
- 11. Module Support
- Appendix A: Definitions
- Appendix B: Agency Certifications
- United States FCC
- OEM Labeling Requirements
- FCC Notices
- FCC-Approved Antennas (2.4 GHz)
- Europe (ETSI)
- OEM Labeling Requirements
- Restrictions
- Declarations of Conformity
- Approved Antennas
- XBee RF Module
- XBee-PRO (S2) RF Module
- XBee-PRO (S2B) RF Module
- Canada (IC)
- Transmitters for Detachable Antennas
- Detachable Antenna
- Appendix C: Migrating from ZNet 2.5 to XBee ZB
- Appendix D: Additional Information
©2009DigiInternational,Inc. 74
7.ManagingEndDevices
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.