PWM signal not detected in Mach3 Board Grblhal

[adepacarmerah]

Hi Terje, I have successfully installed grblhal on the mach3 board and it can run smoothly, but the problem is that the spindle enable output on out 1 does not output a PWM signal and also the Avi and Acm pins do not output a PWM signal, thank you.

[terjeio]

Sorry for late response.

Out1 is an open collector output and is for the spindle enable signal. 24V has to be connected and a load (relay coil or resistor?) has to be connected between 24V and out1 to get any signal. PWM on ACM requires 10V connected since the output is isolated from the rest of the circuitry. This should all be described in the board manual.

Since the PWM output is driven via a rather slow optocoupler the PWM frequency should be reduced to 1KHz by setting $33=1000 if more precice speed control is required.