Controller’s output ports (AUX0-15, M3, M4, M7, M8) are all driven by ULN2803A, with open collector outputs and an output current of up to 500mA, so they can directly drive relays or solenoid valves.
The 16 auxiliary outputs, AUX0-15, can be controlled using the standard G-codes M62-M65.
https://linuxcnc.org/docs/stable/html/gcode/m-code.html#mcode:m62-m65
Below is an example using a 5V relay, controlled by the M3 command to switch the relay on and off:
After connecting the circuit, enter M3S100 in the MDI and click execute to hear the relay engage.
If using a 12V or 24V relay, simply connect both VCC and IN to 12V or 24V.
