XBee ZigBee networks End Device operation
XBee/XBee-PRO ZigBee RF Modules User Guide 49
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.
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.
Once the end device joins a network, the network configuration settings can persist through power cycles as
mentioned in Persistent data on page 48. 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)
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.
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