XBee®/XBee‐PRO® ZB SMT RF Modules
In the figure above, t1, t2, t3 and t4 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.
• t4 - Time when the module sends a poll request to its parent.
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. the time between t3 and t4 is 1-2 ms for a regular module and about 6 ms for a
PRO module.
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.
© 2010 Digi International, Inc.
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DCD [ DIGITAL CORE DESIGN ]
