Edit: Removed PWM signal wire and tested without load. Correct voltage is detected with no load. My assumption is it has something to do with needing to share a common ground with VFD/Shapeoko control board. Will attempt using a PWM>Voltage converter and see if that straightens things out.
Had this issue since installing my spindle. The PWM output from the shapeoko board is non-linear. Speeds (voltage) below 12000rpm (50% are low) and speeds above are too high. Is there a way to adjust the scaling?
Currently I have $30=24000 $31=0 and get the following voltages at various rpms using M3SXXXXX command and measuring using a multi-meter (which agrees with the freq displayed by the VFD). There seems to be a crossover around 55% max speed. Any suggestions?
Requested rpm - measured voltage - expected voltage - difference
|8000|1.062|1.667|-0.605|
|10000|1.605|2.083|-0.478|
|12000|2.455|2.500|-0.045|
|14000|3.292|2.917|0.375|
|16000|3.89|3.333|0.557|
|18000|4.29|3.750|0.540|
|20000|4.59|4.167|0.423|
|24000|5.01|5.000|0.010|
I have the same spindle (I think), min 8000, max 24000 and those are the values I have for $30 & #31. I get very close to those speeds on the VFD when I make spindle calls. They are not exact, but close. I haven’t measured voltages though.
I’m having this same issue but I’m getting incorrect voltage at the pins without load. I’m only getting the correct voltage at 12k rpm but other rpms the voltage is skewed. My board seems unable to output a full 5 volts. What version is your board?
PWM signal does not vary linearly with voltage. It is a square wave train that varies in width as the parameter value varies. It is often put through a low-pass filter to get a voltage signal but it will never read Vmin or Vmax because then there would not be a pulse wave modulation.
The way to actually check the PWM is with a scope to see the waveform pattern & check how the width of the pulses changes with the specified RPM value.