XBee®/XBee‐PRO® ZB SMT RF Modules
•Sends an API modem status frame ("associated") out the serial port when using API mode.
These behaviors are configurable using the following commands:
Command
Description
NJ
Sets the permit-join time on the router, or the time that it will allow new
devices to join the network, measured in seconds. If NJ=0xFF, permit
joining will always be enabled.
D5
LT
Enables the Associate LED functionality.
Sets the Associate LED blink time when joined. Default is 2 blinks per
second (router).
Permit Joining
The permit joining attribute on the router is configurable with the NJ command. NJ can be configured to always
allow joining, or to allow joining for a short time.
Joining Always Enabled
If NJ=0xFF (default), joining is permanently enabled. This mode should be used carefully. Once a network has
been deployed, the application should strongly consider disabling joining to prevent unwanted joins from
occurring.
Joining Temporarily Enabled
If NJ < 0xFF, joining will be enabled only for a number of seconds, based on the NJ parameter. The timer is
started once the XBee joins a network. Joining will not be re-enabled if the module is power cycled or reset. The
following mechanisms can restart the permit-joining timer:
• Changing NJ to a different value (and applying changes with the AC or CN commands)
• Pressing the commissioning button twice
• Issuing the CB command with a parameter of 2 (software emulation of a 2 button press)
• Causing the router to leave and rejoin the network.
The middle two cases enable joining for one minute if NJ is 0x0 or 0xFF. Otherwise, the commissioning button
and the CB2 command enable joining for NJ seconds.
Router Network Connectivity
Once a router joins a ZigBee network, it remains connected to the network on the same channel and PAN ID as
long as it is not forced to leave. (See “Leaving a Network” section for details.) If the scan channels (SC), PAN ID
(ID) and security settings (EE, KY) do not change after a power cycle, the router will remain connected to the
network after a power cycle.
If a router may physically move out of range of the network it initially joined, the application should include
provisions to detect if the router can still communicate with the original network. If communication with the
original network is lost, the application may choose to force the router to leave the network (see Leaving a
Network section below for details). The XBee firmware includes two provisions to automatically detect the
presence of a network, and leave if the check fails.
Power-On Join Verification
The JV command (join verification) enables the power-on join verification check. If enabled, the XBee will
attempt to discover the 64-bit address of the coordinator when it first joins a network. Once it has joined, it
will also attempt to discover the 64-bit address of the coordinator after a power cycle event. If 3 discovery
attempts fail, the router will leave the network and try to join a new network. Power-on join verification is
disabled by default (JV defaults to 0).
Network Watchdog
The NW command (network watchdog timeout) can be used for a powered router to periodically check for
the presence of a coordinator to verify network connectivity. The NW command specifies a timeout in
© 2010 Digi International, Inc.
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DCD [ DIGITAL CORE DESIGN ]
