Digi XBee3 802.15.4 User Manual

Networking Direct and indirect transmission
Digi XBee3® 802.15.4 RF Module User Guide
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Configure an indirect messaging coordinator
A device becomes an indirect messaging coordinator once CE command = 1 and SP command is not 0.
We recommend ensuring that SP and ST are set to the same values on the indirect messaging
coordinator and end device, even if the indirect messaging coordinator is not configured to sleep. This
is to allow the indirect messaging coordinator to send messages directly if it knows the end device is
awake and sleeping cyclically.
If you are going to use a Master/Slave network with indirect messaging, ensure that the indirect
messaging coordinator is also the network coordinator by allowing association (set bit 2 of A2
(Coordinator Association) to 1).
Send indirect messages
To send an indirect message, ensure that the previous requirements are met and transmit normally.
The indirect messaging coordinator queues the message until the end device requests data or the
message is in the indirect queue for 2.5 times the value of SP.
Ensure that the message is sent to the addressed specified by MY command on the end device. If MY
on the end device is 0xFFFF or 0xFFFE, then you must use the 64-bit address, otherwise use the value
of MY. Even though an end device configured with a short address always receives direct
transmissions destined to its 64-bit address, it will not receive an indirect message directed at its 64-
bit address if it is configured to use a 16-bit address.
If the indirect messaging coordinator is operating in API mode, then after transmitting an indirect
message the usual TX status frame (Transmit Status frame - 0x8B or TX Status frame - 0x89) is not
immediately generated by the device. If the end device polls for the data within the timeout (2.5 * SP),
then a TX status frame with status 0x00 (message sent) is sent. If the message is discarded due to
the timeout expiring, the status frame is 0x03 (message purged).
After receiving a poll request and transmitting data to an end device, the indirect messaging
coordinator sends all messages directly until ST time has elapsed. This is because after receiving RF
data, the end device stays awake for ST time if configured in Cyclic Sleep mode (SM = 4). After ST time
has elapsed, messages are sent indirectly again.
The Coordinator currently is able to retain up to five indirect messages.
Receive indirect messages
End devices must poll the indirect messaging coordinator in order to receive indirect messages.
There are three ways to generate a poll request:
n End devices using cyclic sleep automatically send a poll to the coordinator when they wake up
unless SO bit 0 is set.
n End devices using pin sleep may be configured to send a poll on a pin wakeup by setting bit 3 of
A1.
n Use FP (Force Poll) to manually send a poll to the coordinator. In Transparent mode, the poll
request is not sent until the command is exited.
The poll is sent to the address located in DH and DL, so ensure that they are set to match the
coordinator's source addressing mode. If the end device (A1 bit 2 set) has associated with a
coordinator (A2 bit 2 set and CE = 1), then DH and DL are automatically set to the correct values. If
you use indirect messaging in a P2P network, DH and DL have to be set manually on the end device to
point towards the indirect messaging coordinator.
It is more difficult to use indirect messaging 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

Digi XBee3 802.15.4 Specifications

General

Brand	Digi
Model	XBee3 802.15.4
Category	Control Unit
Language	English