Operation
Node discovery
When the node discovery command is issued in AT command mode, all other AT commands are
inhibited until the node discovery command times out, as specified by the NT parameter. After the
timeout, an extra CRLF is output to the terminal window, indicating that new AT commands can be
entered. This is the behavior whether or not there were any nodes that responded to the broadcast.
When the node discovery command is issued in API mode, the behavior is the same except that the
response is output in API mode. If no nodes respond, there will be no responses at all to the node
discover command. The requesting node is not able to process a new AT command until NT times out.
Node discovery in compatibility mode
Node discovery (without an NI string parameter) in compatibility mode operates the same in
compatibility mode as it does outside of compatibility mode with one minor exception:
If C8 bit 1 is set and if requesting node is operating in API mode and if no responses are received by
the time NT times out, then an API AT command response of OK (API frame type 0x88) is sent out the
serial port rather than giving no response at all, which would happen if C8 bit 1 is not set.
Directed node discovery
The directed node discovery command (ND with an NI string parameter) sends out a broadcast to find
a node in the network with a matching NI string. If such a node exists, it sends a response with its
information back to the requesting node.
In Transparent mode, the requesting node will output an extra CRLF following the response from the
designated node and the command will terminate, being ready to accept a new AT command. In the
event that the requested node does not exist or is too slow to respond, the requesting node outputs
an ERROR response after NT expires.
In API mode, the response from the requesting node will be output in API mode and the command will
terminate immediately. If no response comes from the requested node, the requesting node outputs
an error response in API mode after NT expires.
Directed node discovery in compatibility mode
The behavior of the Legacy 802.15.4 module (S1 hardware) varies with the default behavior described
above for the directed node discovery command. The Legacy module does not complete the
command until NT expires, even if the requested node responds immediately. After NT expires, it
gives a successful response, even if the requested node did not respond. To enable this behavior to be
equivalent to the Legacy 802.15.4 module, set bit 1 of the C8 parameter.
Destination Node
The Destination Node command (DN with an NI string parameter) sends out a broadcast containing
the NI string being requested. The responding node with a matching NI string sends its information
back to the requesting node. The local node then sets DH/DL to match the address of the responding
node. As soon as this response occurs, the command terminates successfully. If operating in AT
command mode, an OK string is output and command mode exits. In API mode another AT command
may be entered.
If an NI string parameter is not provided, the DN command terminates immediately with an error. If a
node with the given NI string doesn't respond, the DN command terminates with an error after NT
times out.
Unlike ND (with or without an NI string), DN does not cause the information from the responding
node to be output; rather it simply sets DH/DL to the address of the responding node. If the
responding node has a short address, then DH/DL is set to that short address (with DH at 0 and the
XBee/XBee-PRO S2C 802.15.4 RF Module User Guide
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ETC [ ETC ]
