How do I use the M67 command to toggle a laser?

Hi,

it was suggested to me in another thread that rather than using Z up/down movement to turn a laser on and off, I should use the M67 command.
I guess this is good advice, however, I have no idea how to do that (and I could not find any information that helped me much).

I am using Inkscape and the gcodetools plugin to generate gcode for my laser engraver (which is missing the laser part, but I am willing to substitute it with a LED for the moment, just to see if the blinky lights will actually blink), and as I am fairly new to this CNC thing, I am a bit overwhelmed.


How do I use M67? I guess I will somehow have to bind the command to one of the leftover outputs on my parallel port via HAL, is that correct?
But first, how do I include M67??

Thanks, Christian

I would rather suggest using the spindle pins for the laser instead of M6x - you'll likely get better performance

-m

why do you not want to use the M3 - M5 commands ?
i cant see any reason not to , all the lasers i use , and have built use this method ,
at least using M3 & M5 would mean the laser would not turn on untill the z axis was in the correct position and focal point reached
( if z axis is movable of course )
i link spindle speed to pwm for laser power output .