Digi International Inc XBEEPRO2 Manuel D’Utilisation

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 end device 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 end device has joined, the OP and CH commands will indicate the operating 64-bit 
PAN ID and channel the end device 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 end device will attempt to enter low power sleep modes based on its sleep 
configuration commands (SM, SP, SN, ST, SO).

As mentioned previously, routers and end devices must scan one or more channels to discover a valid network 
to join. When a join attempt begins, the XBee sends a beacon request transmission on the lowest channel 
specified in the SC (scan channels) command bitmask. If a valid PAN is found on the channel, the XBee will 
attempt to join the PAN on that channel. Otherwise, if a valid PAN is not found on the channel, it will attempt 
scanning on the next higher channel in the SC command bitmask. The XBee will continue to scan each channel 
(from lowest to highest) in the SC bitmask until a valid PAN is found or all channels have been scanned. Once all 
channels have been scanned, the next join attempt will start scanning on the lowest channel specified in the SC 
command bitmask.

For example, if the SC command is set to 0x400F, the XBee would start scanning on channel 11 (0x0B) and scan 
until a valid beacon is found, or until channels 11, 12, 13, 14, and 25 have been scanned (in that order).

Once an XBee router or end device joins a network on a given channel, if the XBee is told to leave (see "Leaving 
a Network" section), it will leave the channel it joined on and continue scanning on the next higher channel in 
the SC bitmask. 

For example, if the SC command is set to 0x400F, and the XBee joins a PAN on channel 12 (0x0C), if the XBee 
leaves the channel, it will start scanning on channel 13, followed by channels 14 and 25 if a valid network is not 
found. Once all channels have been scanned, the next join attempt will start scanning on the lowest channel 
specified in the SC command bitmask.

In some applications, multiple ZigBee networks may exist in proximity of each other. The application may need 
provisions to ensure the XBee joins the desired network. There are a number of features in ZigBee to manage 
joining among multiple networks. These include the following:

•PAN ID Filtering
•Preconfigured Security Keys
•Permit Joining
•Application Messaging

The XBee can be configured with a fixed PAN ID by setting the ID command to a non-zero value. If the PAN ID 
is set to a non-zero value, the XBee will only join a network with the same PAN ID. 

Similar to PAN ID filtering, this method requires a known security key be installed on a router to ensure it will 
join a ZigBee network with the same security key. If the security key (KY command) is set to a non-zero value, 
and if security is enabled (EE command), an XBee router or end device will only join a network with the same 
security key.