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ZigBee networks ZigBee coordinator operation
XBee/XBee-PRO® S2C ZigBee® RF Module 58
ZigBee device objects
The ZDO (endpoint 0) supports the discovery and management capabilities of the ZigBee Device
Profile. See the ZigBee specification for a complete listing of all ZDP services. 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. For more information, see
ZDO transmissions .
ZigBee coordinator operation
Form a network
The coordinator is responsible for selecting the channel, PAN ID, 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 topics.
Security policy
The security policy determines which devices are allowed to join the network, and which device(s) can
authenticate joining devices. See
ZigBee security for a detailed discussion of various security policies.
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 (that is, frequencies) to detect energy
levels on each channel. The coordinator removes channels with excessive energy levels 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 (broadcast) transmission on each potential channel. All nearby coordinators and
routers that have already joined a ZigBee network respond to the beacon request by sending a
beacon back to the coordinator. The beacon contains information about which 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.
Persistent data
Once a coordinator starts a network, it retains the following information through power cycle or reset
events:
n
PAN ID