Digi XBee S2C Zigbee User Manual page 85

Zigbee networks
If any of the events listed above occur during the watchdog period then no additional network traffic
will be generated. If the watchdog timer does expire (no valid data received for 1 NW time period), the
router attempts to initiate communication with the coordinator by sending an IEEE 64-bit address
discovery message to the coordinator. If the router cannot discover the address, it records one
watchdog timeout. After three consecutive network watchdog timeouts expire (3 * NW) and the
coordinator has not responded to the address discovery attempts, the router will enter one of three
modes based on the configuration of
Options) bit 7:
1. No Network Locator (Leave Network): If neither DC bit 5 or DO bit 7 is set, the router will
immediately leave the network and begin searching for a network to join based on its
networking settings. If API mode is enabled, a network disassociated modem status frame
(0x03) will be emitted when the router leaves the network. If the router finds and joins a new
coordinator or the original coordinator, a joined network modem status frame (0x02) will be
emitted if API mode is enabled.
2. Network Locator with Network Leave: If DO bit 7 is set but DC bit 5 is not set, the behavior of
JV and NW are modified. The router will remain on the network until a new network is found.
The router starts scanning for a network across the channels of the Scan Channel mask (SC).
Scanning occurs at a random interval of between 90 and 135 seconds. If API mode is enabled, a
network watchdog scanning modem status frame (0x42) will be emitted when scanning begins.
If the device finds a network on the old channel with the same OI and operating ID, the search
mode ends. If the device finds a network with a new OI but satisfies the device's search for a
matching ID and ZS, the device leaves the old network and joins the new network with the new
OI. These leave and join actions will cause the router to emit a disassociated network modem
status (0x03) and a joined network modem status frame (0x02) if API mode is enabled. This
supports swapping or replacing a coordinator in a running network.
3. Network Locator with Rejoin: If DC bit 5 is set, the router will begin scanning the current
channel indefinitely in an attempt to find the coordinator on the original network or re-join the
coordinator if it has moved to a new network. If API mode is enabled, a network watchdog
scanning modem status frame (0x42) will be emitted when scanning begins. Scanning occurs at
a random interval of between 90 and 135 seconds. If it finds the coordinator which must have a
matching ID (extended PAN ID) with the same PAN ID (OI) or a new PAN ID, the router will
rejoin the coordinator even if the coordinator is configured with a NJ of 0 (joining disabled). If
the router finds the coordinator on the original network or rejoins coordinator on a new
network, a joined network modem status frame (0x02) will be emitted if API mode is enabled.
Leave a network
The following mechanisms cause the coordinator to leave its current PAN and start a new network
based on its network formation parameter values.
Change the ID command such that the current 64-bit PAN ID is invalid.
n
Change the SC command such that the current channel (CH) is not included in the channel
n
mask.
Change the ZS or any of the security command values.
n
Send the NR0 command to cause the coordinator to leave.
n
Send the NR1 command to send a broadcast transmission, causing all devices in the network
n
to leave and migrate to a different channel.
XBee/XBee-PRO® S2C Zigbee® RF Module User Guide
DC (Joining Device Controls)
Router operation
bit 5 and DO (Miscellaneous Device
85