How can I test to see if an Auxout is activated?

Using G-code commands, you can test to see if an auxout is activated. For example, if, in a macro, you want to check if the spindle is on, and the spindle output channel is C20, here is how you would test to see if the spindle is on. The line of gcode that follows the M17.1 command will be run only if C20 (the spindle's output channel) is on, otherwise, the line that follows will be skipped.

M17.2 C20 [TEST TO SEE IF OUTPUT 20 IS ON]
G4 [This prompt will appear if the spindle is on.]