Unusual use of M8/M9 to control a compressor

[Doddy]

Something like



All depends on your use-case. In this example UCCNC simply bypasses the manual switches to force the compressor on. Set the M8 command pin/port on setup/spindle page.

You would still be able to turn on the compressor with the existing switches, but not turn off the compressor with the switches if enabled by the AXBB.

That relay?, if it's the right coil voltage and current to suit the AXBB?

EDIT: You could glam up the circuit but there's a certain KISS approach to the above.