XBee®/XBee‐PRO® ZB SMT RF Modules
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.
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.
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
EE
Set the stack profile on the device.
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
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