Mach3 RNR USB controller using a spindle and laser, the laser is mounted with an offset to the spindle.
M3, M5 for spindle ON\OFF toggle
M4, M5 for Laser ON\OFF toggle
PWM S0 for 0% (off) and S1000 for 100% laser power

The custom Aspire PostP work well for both, laser with offset and standard laser on offset

A wiring diagram can be downloaded from the link below.
http://www.3dwhat.co.za/cnc.php

Check StevesFascinations channel out for PWM explained in more detail with a similar setup
   • S9 Laser/Mach3/USBCNC