I've read through the links you gave me, thanks! There's a LOT of information on your laser project thread. 😊
Are you still using the inline parallel port with the opto-couplers? I'd saw the pictures before but never really took it in, exactly what I was looking at. That's some fantastic work you've done!
Do you have the specification for the opto-couplers and the LED resistors (so I can search on eBay for them)? Also can the two parallel ports with the breadboard be bought, or did you custom build that as well? I know it's not a breakout board as such but it's doing the same job. It's probably obvious to you but, I'm not too experienced with electronics. I can solder and the circuit layout doesn't look too complicated but all these things are easy, when you know how! Your instructions/schematics are really good, I just need some part numbers/specs to start.
I've also read Jtech photonics options for controlling a laser using Mach3. They recommend using a TB6560 4axis board or a DB25 Dual BOB adapter. Are these like 'off the shelf' versions of your setup?
I checked my parallel port on my computer and unfortunately it has 3.3v outputs. I have older computers laying around so, I'll get one that has 5v outputs.
Finally, I haven't been able to get confirmation that the ESS will work alongside the parallel port. I was thinking/hoping that if I enabled the second parallel port in Mach3 settings then, the 2nd parallel port would control the laser and the ESS would control everything else.