Xbee Series 2 Networks; Xbee Series 2 Network Formation; Starting An Xbee Series 2 Coordinator; Joining An Xbee Series 2 Router To An Existing Pan - AG Electronica XBee 2 Series Manual

www.agelectronica.com
4. XBee Series 2 Networks

4.1. XBee Series 2 Network Formation

4.1.1. Starting an XBee Series 2 Coordinator

4.1.2. Joining an XBee Series 2 Router to an existing PAN

4.1.3. Joining an XBee Series 2 End Device to an Existing PAN

www.agelectronica.com
To create a ZigBee network, a coordinator must be started on a channel and PAN ID. Once the
coordinator has started, routers and end device can join the network. Routers and coordinator
devices can support up to 8 end device children each. Network formation is governed by the SC
(Scan Channels), ID (PAN ID), SD (Scan Duration), and NJ (Node Join Time) commands. The SC
and ID settings should be written using the WR command to preserve network formation or joining
information."
In order to form a network, a coordinator must select an unused operating channel and PAN ID on
behalf of its network. To do this, the coordinator first performs an energy scan on all channels
specified by its SC (Scan Channels) parameter. The scan time on each channel is determined by
the SD (Scan Duration) parameter. Once the energy scan is completed, the coordinator sends a
beacon request on each of the SC channels and listens for any beacons. The information from the
energy scan and the beacon scan (active scan) is used to select an unused channel and PAN ID. If
the ID (PAN ID) parameter is set to 0xFFFF, the coordinator will select a random PAN ID.
Otherwise, the coordinator will start on the PAN ID specified by its ID parameter.
After the coordinator has started, it will allow nodes to join to it for a time based on its NJ (Node
Join Time) parameter. If the Associated LED function is enabled (D5 (DIO5 Configuration)
command), the Associate pin (pin 15) will toggle its output state 1x per second after the
coordinator started. At this point, the operating channel and PAN ID can be read using the CH
(Operating Channel) and ID (PAN ID) commands. The 16-bit address of the coordinator is always
0. If API is enabled (AP parameter > 0): The API modem status "coordinator Started" frame is
sent out the UART. The AI (Association Indication) command can be used at any point during the
coordinator startup routine to determine the status of the startup operation.
Before a router can participate in a ZigBee network, the router must locate a coordinator or
another router that has already joined a PAN, and attempt to join to it. To do this, it sends a
beacon request frame on each of the SC channels and listens for beacon frames. The scan duration
on each channel is determined by the SD parameter. The joining router will evaluate the received
beacons to find a coordinator or router that is allowing joins on a valid PAN ID, and attempt to join
to that device. If ID = 0xFFFF, the router will attempt to join to a device on any PAN ID. Otherwise,
the router will only attempt joining with a device that operates on the PAN ID specified by the ID
parameter. If a valid router/ coordinator is found, the router will attempt to join to that node. If
the join succeeds, the Router has successfully started.
After the Router has started, it will allow nodes to join to it for a time based on the NJ (Node Join
Time) parameter. If the Associated LED function is enabled(D5 (DIO5 Configuration) command)
the Associate pin (pin 15) will toggle its output state 2x per second after the router has joined. At
this point, the operating channel and PAN ID can be read using the CH (Operating Channel) and ID
(PAN ID) commands. The 16-bit network address of the router can be read using the MY (16-bit
Source Address) command. If API is enabled (AP parameter > 0): The API modem status "Joined"
is sent out the UART. If the JN command is enabled, the router will send a node identification
packet to the coordinator. The AI (Association Indication) command can be used at any point
during the router join routine to know the status of the startup operation.
Joining an end device to a PAN is similar to joining a router. Once the end device joins a PAN,
however, the end device cannot allow other devices to join to it. If the Associate LED function is
enabled (D5 (DIO5 Configuration) command), the Associate pin (pin 15) will toggle its output
© 2007 Digi International, Inc.
www.agelectronica.com
25
www.agelectronica.com