Zigbee networks Channel scanning
Digi XBee® 3 Zigbee® RF Module
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Once the end device joins a network, the network configuration settings persist through power cycles
as mentioned in Persistent data. If joining fails, read the status of the last join attempt in the AI
command register.
If any of these command values change when command register changes are applied, the end device
leaves its current network and attempts to discover and join a new valid network.
When a Zigbee end device has successfully started a network, it:
n Sets AI equal to 0
n Starts blinking the Associate LED if one has been connected to the device's ASSC pin (Micro pin
26/SMT pin 28/TH pin 15)
n Sends an API modem status frame (“associated”) out the serial port when using API mode
n Attempts to enter the sleep mode defined by the SMparameter
You can use the following commands to configure these behaviors:
Command Description
D5
Enables the Associate LED functionality.
LT
Sets the Associate LED blink time when joined. Default is 2 blinks per second
(end devices).
SM, SP, ST, SN, SO,
ET
Parameters that configure the sleep mode characteristics. See End Device
configuration.
Parent connectivity
The XBee 3 Zigbee RF Module end device sends regular poll transmissions to its parent when it is
awake. These poll transmissions query the parent for any new received data packets. The parent
always sends a MAC layer acknowledgment back to the end device. The acknowledgment indicates
whether the parent has data for the end device.
If the end device does not receive an acknowledgment for three consecutive poll requests, it
considers itself disconnected from its parent and attempts to discover and join a valid Zigbee
network. For more information, see Manage End Devices.
Reset the end device
When the end device is reset or power cycled, if the orphan scan successfully locates a parent, the end
device then checks its PAN ID, operating channel and stack profile against the network configuration
settings (ID, SC, ZS). It also verifies the saved security policy is valid based on the security
configuration commands (EE, EO, KY). If the end device's PAN ID, operating channel, stack profile, or
security policy is invalid, the end device will leave the network and attempt to join a new network
based on its network joining command values.
To prevent the end device from leaving an existing network, the WR command should be issued after
all network joining commands have been configured in order to retain these settings through power
cycle or reset events.
Channel scanning
Routers and end devices must scan one or more channels to discover a valid network to join. When a
join attempt begins, the device sends a beacon request transmission on the lowest channel specified
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