XBee®/XBee‐PRO® ZB SMT RF Modules
minutes where the router must receive communication from the coordinator or data collector. The following
events restart the network watchdog timer:
•RF data received from the coordinator
•RF data sent to the coordinator and an acknowledgment was received
•Many-to-one route request was received (from any device)
•Changing the value of NW.
If the watchdog timer expires (no valid data received for NW time), the router will attempt to discover the
64-bit address of the coordinator. If the address cannot be discovered, the router records one watchdog
timeout. Once three consecutive network watchdog timeouts have expired (3 * NW) and the coordinator
has not responded to the address discovery attempts, the router will leave the network and attempt to join
a new network. Anytime a router receives valid data from the coordinator or data collector, it will clear the
watchdog timeouts counter and restart the watchdog timer. The watchdog timer (NW command) is settable
to several days. The network watchdog feature is disabled by default (NW defaults to 0).
Network Watchdog Behavior
Clear Network Watchdog Failure Count
Restart Network Watchdog Timer
Received RF
Yes
No
Communication from
Coordinator or Data
Collector
No
Network Watchdog
Timer Expired?
Yes
Discover Coordinator
Network
Watchdog
No
Failure Count
=3?
No
Coordinator
Found?
Network Watchdog Failure
Count +=1
Yes
Yes
Leave
Leaving a Network
There are a couple of mechanisms that will cause the router to leave its current PAN and attempt to discover
and join a new network based on its network joining parameter values.
These include the following:
© 2010 Digi International, Inc.
43
DCD [ DIGITAL CORE DESIGN ]
