User's Manual

Table Of Contents
XBee®/XBeePRO®ZBRFModules
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In the figure above, t1, t2, and t3 represent the following events:
•T1 - Time when Sleep_RQ is asserted (high)
T2 - Time when the XBee enters sleep (CTS state change only if hardware flow control is
enabled)
T3 - Time when Sleep_RQ is de-asserted (low) and the module wakes.
The time between T1 and T2 varies depending on the state of the module. In the worst case
scenario, if the end device is trying to join a network, or if it is waiting for an acknowledgment
from a data transmission, the delay could be up to a few seconds.
When the XBee is awake and is joined to a network, it sends a poll request to its parent to see if
the parent has any buffered data for it. The end device will continue to send poll requests every
100ms while it is awake.