XBee® Wi-Fi RF Modules
© 2013 Digi International, Inc. 55
If the IS command is issued in command mode, the module returns a carriage return-
delimited list containing the above-listed fields. If the IS command is issued in API mode,
the module returns an API command response packet with the I/O data included in the
command data portion of the response frame.
The following table shows an example of the fields in an IS response.
Example Sample AT Response
0x01 [1 sample set]
[Digital Inputs: DIO 2, 3, 10, 11 selected]
0x03 [Analog Inputs; A/D 0,1]
0x0408 [Digital input states: DIO 3,10 high, DIO 2,11 low]
[Analog input ADIO 0=0x3D0]
[Analog input ADIO 1=0x120]
Periodic I/O Sampling
Periodic sampling allows the XBee module to take an I/O sample and transmit it to a
remote device at a periodic rate. The periodic sample rate is set by the IR command. If
IR is set to 0 or there are no active I/O lines, periodic sampling is disabled. For all other
values of IR, data will be sampled after IR milliseconds have elapsed and transmitted to
a remote device. However, the module cannot keep up with transmitting an I/O sample
more often than every three milliseconds. Therefore, when IR is set to 1 or 2, many
samples are lost. The DL command determines the destination address of the I/O
samples. DL can be set to transmit to a network client or another XBee Wi-Fi module.
Only modules with API mode enabled for the serial port can send I/O data samples out
their serial port. Network clients will receive the I/O data packet as described in the
XBee IP Services chapter.
IR can be used with sleep. A module will transmit periodic I/O samples at the IR rate
until the ST timer expires, the SleepRq line is asserted, and the device can resume
sleeping. Even if the IR rate is set longer than the ST defined wake time, at least one I/O
sample will still be sent before the module returns to sleep because it sends one
immediately upon wake up. If it is not desired that a sample is sent every wake cycle,
the IF command can be used to configure how many wake cycles should elapse before
sending I/O samples at the IR rate.
Change Detection Sampling
Modules can be configured to transmit a data sample immediately whenever a
monitored digital I/O pin changes state. The IC command is a bitmask that can be used
to set which digital I/O lines should be monitored for a state change. If one or more bits
in IC is set, an I/O sample will be transmitted as soon as a state change is observed in
one of the monitored digital IO lines. Change detection samples are transmitted to the
IPv4 address specified by DL.
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