How to properly connect LASER and control its power?

I read forum.linuxcnc.org/10-advanced-configura...pwm-output-for-laser, read Google + AI. The result is zero. 
Let's keep it simple. Let's say my configuration doesn't mention anything about the spindle or the laser. 

How exactly should I format the hal file?
The scenario is as follows: there is a laser, controlled by PWM via LPT. It has been proven that the laser itself works. It has been proven that PWM also works (because we control the spindle through it).
The documentation indicates that we must set several mandatory parameters. It would seem that this is sufficient.

linuxcnc.org/docs/2.8/html/man/man9/pwmgen.9.html
forum.linuxcnc.org/media/kunena/attachme...19092/FRANKENLAB.hal
forum.linuxcnc.org/media/kunena/attachme...-mill_2019-07-26.hal
#spindle section 
loadrt pwmgen output_type=0
    addf pwmgen.make-pulses base-thread #enabled PWM frequency signal generation
    addf pwmgen.update servo-thread #enabled control synchronization with the servo cycle
    
    net spindle-pwm <= pwmgen.0.pwm #set the name of the signal controlled by the pwmgen.0.pwm signal
    net spindle-pwm  => parport.0.pin-14-out  #set the LPT port pin to which the signal is transmitted
    setp pwmgen.0.dither-pwm true  #enabled frequency regulation stepping
        setp pwmgen.0.pwm-freq 100.0
        setp pwmgen.0.scale 24000


The spindle can be controlled normally with these parameters. If you connect a laser PWM to pin 14 instead, the laser should work somehow, either via M68 or M3S24000.

But the laser does not turn on. Only with the forced activation button on the laser body, and immediately at 100% power.

What am I doing wrong?

The laser has 3 inputs. PWM, +12v and ground.

Good question. The laser has three inputs: 
1. PWM
2. +12V
3. Ground. 

Is 3 ground or -12V?

The laser itself operates from the mechanical switch button on the laser. Logically, it needs a separate + and a separate -. I don't see a ground contact.
When attempting to connect pin 3 (ground) of the laser to the ground of the control board (instead of minus 12V), the laser does not flash and the fan does not spin.

Connected the laser mounting screw to the machine and the control board ground contact with a wire. No changes.
I connected a voltmeter directly to the wire at the laser input.
At m30, the voltage is 0.26, and at m3, the voltage is 4.7. The spindle frequency converter is connected here as well and is controlled normally.

The machine controller board indicator also responds appropriately—it turns on and off at m3 or m30.