Wolffie, I apologize If I interpreted your comment incorrectly.
I have been using another program that has enhancements for laser diode engraving for quite some time now, but will not name it here. PVC is capable of producing the g-code for laser engraving with the correct control means and there are different ways to do it. I have a 1W 445nm laser diode and use a MA3 US Digital analog shaft encoder tied to my Z axis stepper motor by timing belts to control the modulation to the laser. I have been running this setup for over 800 hours now with no failures.
I explain in more detail how I set this up on my router in this thread. viewtopic.php?f=16&t=15161
Dave came up with another way to control the modulation using the step and direction pins from Mach and his circuit is referenced in his thread.viewtopic.php?f=16&t=15339
Now there is a third way that Dave discovered after I referenced another Maxim Digital Potentiometer chip. This Digital Potentiometer he found can take the step and direction from Mach and give the 256 steps needed to vary the power to the laser to get the 8-bit shades of grey. http://www.datasheetcatalog.org/datashe ... AX5455.pdf
I have done some testing with the max5451 with successful results, but still prefer the encoder because it has 10-bit resolution. Besides, it's not easy to solder the pins on a TSSOP surface mount chip.
Extensivly Re-worked/Re-designed/Modified Servo K2CNC KG-3925 and the Mini Laser Engraver