M4 does produce a PWM signal in Linuxcnc Debian Stretch

I am using Debian Stretch LinuxCNC. The M3 command produces a Spindle PWM signal but the M4 command does not. Does anyone know how to resolve this problem?

Channel 14 was selected for the Spindle-PWM signal.

The Hal-Scope shows a square wave on Channel 14 when using the M3 command but when using the M4 command, the Hal-Scope shows no output on channel 14.

The MIDI test commands used were M3 S1000 and then M4 S1000. The M3 command controls spindle speed perfectly.

I just fixed this issue as follows:

The solution was to use pwmgen type 1 by editing the HAL file to say,

loadrt pwmgen output_type=1

Then it worked!

This would be a good upgrade to add into the Linuxcnc Step Conf.

Thank you,

Barry