Zigbee networks Zigbee networking concepts
Digi XBee® 3 Zigbee® RF Module
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n Uses less expensive hardware and can power itself down intermittently, saving energy by
temporarily entering a non responsive sleep mode.
n Always needs a router or the coordinator to be its parent device. The parent helps end devices
join the network, and stores messages for them when they are asleep.
Zigbee networks may have any number of end devices. In fact, a network can be composed of one
coordinator, multiple end devices, and zero routers.
The following diagram shows a generic Zigbee network.
Note Each Zigbee network must be formed by one, and only one, coordinator and at least one other
device (router or end device).
In Zigbee networks, the coordinator must select a PAN ID (64-bit and 16-bit) and channel to start a
network. After that, it behaves essentially like a router. The coordinator and routers can allow other
devices to join the network and can route data.
After an end device joins a router or coordinator, it must be able to transmit or receive RF data
through that router or coordinator. The router or coordinator that allowed an end device to join
becomes the “parent” of the end device. Since the end device can sleep, the parent must be able to
buffer or retain incoming data packets destined for the end device until the end device is able to wake
and receive the data.
A device can only operate as one of the three device types. The device type is selected by
configuration rather than by firmware image as was the case on earlier hardware platforms.
By default, the device operates as a router. To select coordinator operation, set CE to 1. To select end
device operation, set SM to a non-zero value. To select router operation, both CE and SM must be 0.
If a device is a coordinator and it needs to be changed into an end device, you must set CE to 0 first. If
not, the SM configuration will conflict with the CE configuration. Likewise, to change an end device into
a coordinator, you must change it into a router first.
Another complication is that default parameters do not always work well for a coordinator.
For example:
n DH/DL is 0 by default, which allows routers and end devices to send transparent data to the
coordinator when they first come up. If DH/DL is not changed from the default value when the
device is changed to a coordinator, then the device sends data to itself, causing characters to
be echoed back to the screen as they are typed. Since this is probably not the desired
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