Mach3 Version 3.043.066 101
Saija Grzegorek
Its may well be corrupted on your xp machine it happens sometime, (in 7 years I have had it happen 3 times) you just overwrite the Mach3 instal, but first copy and paste your Mach3 folder from C/mach3 to your desktop as a backup for your settings and license, It should not stuff anything doing a overwrite just incase.
If you are using mach3 and your have your output for M03 set to an output pin to turn on and off the DAC, then yes it will work. Just set your laser power by jogging your DAC to your desired level, and then run the program generated by the post processor that will turn the DAC on and off for the engraving.
If you are using mach3, make sure your spindle delay is set to zero. Check this on any controller you may be using. If this is still an issue and you are using Mach3, then try to use the M11P#/M10P# direct outputs to control the laser. You can see the details on setting this up here: _id=1436
You can use mach3 to control laser power by setting up the PWM output. You can see the details in this post here: _id=1436
Try messing around with it to see if you can get it to work with your machine. The DAC-PWM board is a much harder way to go versus just getting PWM to work with mach3 outputs.