Specifications
XBee®/XBee‐PRO®SERFModules
©2009DigiInternational,Inc. 20
• After joining, can assist in routing data
• Cannot sleep--should be mains powered.
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 discover 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