6: ZigBee Initialisation and Operation > Joining a ZigBee Network

Joining a ZigBee Network

Once the network has been created by the Co-ordinator, other devices (Routers and End Devices) can join the network. Both Routers and the Co-ordinator have the capability to allow other nodes to join the network. The join process is as follows:

1. Search for Network

The new node first scans the available channels to find operating networks and identifies which one it should join. Multiple networks may operate in the same channel and are differentiated by their PAN IDs.

2. Select Parent

The node may be able to ‘see’ multiple Routers and a Co-ordinator from the same network, in which case it selects which one it should connect to. Usually, this is the one with the best signal.

3. Send Join Request

The node then sends a message to the relevant Router or Co-ordinator asking to join the network.

4. Accept of Reject Join Request

The Router or Co-ordinator decides whether the node is a permitted device, whether the Router/Co-ordinator is currently allowing devices to join and whether it has address space available. If all these criteria are satisfied, the Router/Co-ordinator will then allow the device to join and allocate it an address.

	Typically, a Router or Co-ordinator can be configured to have a time-period during which joins are allowed. The join period may be initiated by a user action, such as pressing a button. An infinite join period can be set, so that child nodes can join the parent node at any time.

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