Hi, I have a CNC machine running Mach3.

The machine was already wired when I got it, I don’t have documentation.

Everything works (X, Y, Z axes), and the spindle starts with M3.

BUT:
The spindle DOES NOT STOP with M5, Stop, or Reset.
It only stops when I close Mach3.

I tried:
- Active Low on/off
- Different Output pins (Port 1 Pin 16 etc.)
- Spindle setup settings

Current setup:
- Output #1: Port 1 Pin 16
- Spindle Relay enabled
- Using relay (not sure about VFD)

Question:
Why would spindle ignore M5 and keep running?
Is this wiring issue or Mach3 configuration?

Thanks!