User Manual

Operation Networking
XBee/XBee-PRO S2C 802.15.4 RF Module User Guide
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should be set to match the SP and ST values of the end nodes. The coordinator will hold onto an
indirect message until it receives a poll from the device to which the message is addressed, or until a
timeout, whichever occurs first. The timeout is 2.5 times the value of SP.
After an indirect message is sent, subsequent messages to the same address will be sent directly for
a period of time equal to the ST parameter. The assumption is that the end device will remain awake
for ST time after the last transmission or reception. Therefore, after a poll, every transmission and
reception involving that address restart the ST timer. After the ST timer expires, the coordinator will
again use indirect messaging (i.e it will hold messages awaiting a poll.)
End devices using cyclic sleep send a poll to the coordinator when they wake up unless SO bit 0 is
set.End devices using pin sleep may be configured to send a poll on a pin wakeup by setting bit 3 of
A1. Also the FP command can be used to send a poll upon exiting command mode. However, the poll is
not sent while in command mode. Rather the poll is sent after changes are applied so that the module
is ready to receive data after the poll is sent.
It is more difficult to use indirect addressing with pin sleep than with cyclic sleep because the end
device must wake up periodically to poll for the data from the coordinator. Otherwise, the coordinator
will discard the data. Therefore, cyclic sleep is the only recommended sleep mode for indirect
addressing.
Association indicators
There are two types of association indicators: Asynchronous device status messages, and on demand
queries. Asynchronous device status messages occur whenever a change occurs and API mode is
enabled. On demand queries occur when the AI command is issued, which can occur in Command
mode, in API mode, or as a remote command.
Device Status Messages
Not all device status messages are related with association, but for completeness all device status
types reported by XBee/XBee-PRO S2C 802.15.4 RF Module are listed in the following table.
Type Meaning
0x00 Hardware reset.
0x01 Watchdog reset.
0x02 End device successfully associated with a coordinator.
0x03 End device disassociated from coordinator or coordinator failed to form a new network.
0x06 Coordinator formed a new network.
0x0D Input voltage on the XBee-PRO device is too high, which prevents transmissions.
Association indicator status codes
The XBee/XBee-PRO S2C 802.15.4 RF Module code can potentially give any of the status codes in the
following table.
Code Meaning
0x00 Coordinator successfully started, End device successfully associated, or operating in peer to
peer mode where no association is needed.
0x03 Active Scan found a PAN coordinator, but it is not currently accepting associations.