[Al_The_Man]

Basically that is it.
You will need to know what particular output(s) that have been assigned to a particular M code, this is done by the machine tool builder, and not Fanuc.
Typically, most M codes when issued will wait for a completion signal, this is normally an input from the device that the M code was issued to.
In some cases where a device does not issue an M code it is returned immediately internally, for example a coolant pump, where it is just turned on/off but has no need to be confirmed.
If for example you were to use this coolant pump M code for your own use, you would have to issue a program stop in the Fanuc program, the operator would then press cycle start after the rotary table was in position.
Al.