When devices enter the Zigbee network…
There are options that can be used for detecting new devices or nodes within a Digi Zigbee network. Using the JN (Join Notification) command will broadcast a Join Notification message upon power up and upon successful join attempt. See more details in the Digi XBee Zigbee product manual.
Also, when security is activated in a network, all associations of new devices are followed by a negotiation with the Trust Center (assumed to be the coordinator). This negotiation can be done using the device or router node that allowed the joining (“joinee”) as a proxy for the communication with the coordinator.
When devices exit the network…
Regarding the detection of devices leaving, your application should NOT depend on getting notifications when devices leave. In normal running systems, devices don’t often leave gracefully (or intentionally), so if a node drops off the network due to some circumstance not under its control, you won’t have the benefit of knowing about it through any official notification. Furthermore, the mechanisms that ZigBee uses to inform devices of a node’s departure are not reliable (broadcasts and un-ACKed Unicasts). Thus, your application design (if it cares very much about the presence/lack of devices) would need to have some mechanism to detect nodes that have dropped out of the network, regardless of whether that departure was intentional.
In summary…
If you enable security or use the JN parameter, you can always depend on knowing when a node is joining your network because it cannot join without the permission of the Trust Center or sending a JN broadcast (if enabled). But a node going offline permanently or semi-permanently is not something you can depend on knowing about since there is no way to detect a node that no longer exists unless there are application heartbeats, table queries, or keepalives to determine the status of each node.
Last updated:
Sep 23, 2020