Specifications
XBee®/XBee‐PRO®SERFModules
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3. If SC or ID is changed from the default, apply changes (make SC and ID changes take effect)
by issuing the AC or CN command.
4. The Associate LED will start blinking once the router has joined a PAN.
5. If the Associate LED is not blinking, the AI command can be read to determine the cause of join
failure.
6. Once the router has joined, the OP and CH commands will indicate the operating 64-bit PAN ID
and channel the router joined.
7. The MY command will reflect the 16-bit address the router received when it joined.
8. The API Modem Status frame ("Associated") is sent out the UART (API firmware only).
9. The joined router will allow other devices to join for a time based on its NJ setting.
End Device Operation
Similar to routers, end devices must also discover and join a valid ZigBee network before they can
participate in a network. After an end device has joined a network, it can communicate with other
devices on the network. Since end devices are intended to be battery powered and therefore
support low power (sleep) modes, end devices cannot allow other devices to join, nor can they
route data packets.
Discovering ZigBee Networks
End devices go through the same process as routers to discover networks by issuing a PAN scan.
After sending the broadcast beacon request transmission, the end device listens for a short time in
order to receive beacons sent by nearby routers and coordinators on the same channel. The end
device evaluates each beacon received on the channel to determine if a valid PAN is found. An end
device considers a PAN to be valid if the PAN:
• Has a valid 64-bit PAN ID (PAN ID matches ID if ID > 0)
• Has the correct stack profile (ZS command)
• Is allowing joining
• Has capacity for additional end devices (see End Device Capacity section below).
If a valid PAN is not found, the end device performs the PAN scan on the next channel in its scan
channels list and continues this process until a valid network is found, or until all channels have
been scanned. If all channels have been scanned and a valid PAN was not discovered, the end
device may enter a low power sleep state and scan again later.
If scanning all SC channels fails to discover a valid PAN, XBee Smart Energy modules will attempt
to enter a low power state and will retry scanning all SC channels after the module wakes from
sleeping. If the module cannot enter a low power state, it will retry scanning all channels, similar
to the router. To meet Smart Energy requirements, the end device will attempt up to three scans.
If all 3 attempts fail, the application or user must retry joining. The following events cause the
XBee to perform up to three join attempts:
• Single commissioning button press (see chapter 7)
• CB command with a parameter of 1
• Resetting the XBee (FR or hardware reset).
Note: The XBee Smart Energy end device will not enter sleep until it has completed scanning all
SC channels for a valid network.
Joining a Network
Once the end device discovers a valid network, it joins the network, similar to a router, by sending
an association request (to the device that sent a valid beacon) to request 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 an end device 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.