XBee®/XBee‐PRO® ZB SMT RF Modules
Orphan Scans
When an end device comes up from a power cycle, it performs an orphan scan to verify it still has a valid parent.
The orphan scan is sent as a broadcast transmission and contains the 64-bit address of the end device. Nearby
routers and coordinator devices that receive the broadcast check their child tables for an entry that contains the
end device's 64-bit address. If an entry is found with a matching 64-bit address, the device sends a coordinator
realignment command to the end device that includes the end device's 16-bit address, 16-bit PAN ID, operating
channel, and the parent's 64-bit and 16-bit addresses.
If the orphaned end device receives a coordinator realignment command, it is considered joined to the network.
Otherwise, it will attempt to discover and join a valid network.
XBee ZB End Device Joining
When an end device is powered on, if it is not joined to a valid ZigBee network, or if the orphan scan fails to find
a parent, it immediately attempts to find and join a valid ZigBee network.
Note: The DJ command can be set to 1 to disable joining. The DJ parameter cannot be written with WR, so a
power cycle always clears the DJ setting.
Similar to a router, the following commands control the end device joining process.
Network joining commands used by an end device to join a network.
Command
Description
ID
Sets the 64-bit PAN ID to join. Setting ID=0 allows the router to join any
64-bit PAN ID.
SC
Set the scan channels bitmask that determines which channels an end
device will scan to find a valid network. SC on the end device should be
set to match SC on the coordinator and routers in the desired network.
For example, setting SC to 0x281 enables scanning on channels 0x0B,
0x12, and 0x14, in that order.
SD
Set the scan duration, or time that the end device will listen for beacons
on each channel.
ZS
EE
Set the stack profile on the device.
Enable or disable security in the network. This must be set to match the
EE value (security policy) of the coordinator.
KY
Set the trust center link key. If set to 0 (default), the link key is expected to
be obtained (unencrypted) during joining.
Once the end device joins a network, the network configuration settings can persist through power cycles as
mentioned in the "Persistent Data" section previously. If joining fails, the status of the last join attempt can be
read in the AI command register.
If any of these command values changes, when command register changes are applied, the end device will
leave its current network and attempt to discover and join a new valid network.
When a ZB end device has successfully started a network, it
• Sets AI=0
• Starts blinking the Associate LED
• Sends an API modem status frame ("associated") out the serial port when using API mode
• Attempts to enter low power modes.
These behaviors are configurable using the following commands:
Command
Description
D5
LT
Enables the Associate LED functionality.
Sets the Associate LED blink time when joined. Default is 2 blinks per
second (end devices).
SM, SP, ST, SN, Parameters that configure the sleep mode characteristics. (See
SO Managing End Devices chapter for details.)
© 2010 Digi International, Inc.
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DCD [ DIGITAL CORE DESIGN ]
