Digi XTend User Manual page 24

Modes of operation
Commands can be queried for their current value by sending the command logically ORed (bit-wise) with the value
0x80 (hexadecimal) with CMD asserted. When the binary value is sent (with no parameters), the current value of the
command parameter is sent back through the DO pin.
The figure shows Binary Command Write then Read
Signal #4 is CMD
Signal #1 is the DI signal
Signal #2 is the DO signal from the radio
Signal #3 is CTS
In this graph, a value was written to a register and then read out to verify it. While not in the middle of other received
data, note that the CTS signal outlines the data response out of the module.
In order for the module to recognize a binary command, the RT (GPI1 Configuration) parameter must be set to one. If
binary programming is not enabled (RT parameter value is not equal to '1'), the module will not recognize that the
CMD pin is asserted and therefore will not recognize the data as binary commands.
XTend RF Module User Guide 24