Dear Allan,
I checked schematics today and both Enables are going trhough a STM microcontroller and are not as fast as analog and TTL line, this is why using them this way may not work.
I also studied Teweakie solution which is smart and allow to modulate the laser quickly.
http://www.tweakie.byethost10.com/27_files/Page1020.htm?i=1Guys tell me if I'm wrong but I think we can use the PLH3D-CNC Adapter inputs a little odd way, but this should make it work.
I'm attaching the schematics of Tweakie circuit and Adapters Analog inputs.
Pin 17 is constantly giving PWM while pin 16 make it work in low state, the current starts to flow and optotransistor shortens the low TTL input of the laser controller.
I'm attaching part of the schematics of the both Analog inputs 10V and 5V. They are protected by Shottky diodes so applying higher voltage will not burn the input.
I could not find quickly if pin 16 is open collector or HIGH/LOW state output.
If PIN 16 is open collector:
If we connect Pin 17 to the ANGIN 10V and PIN 16 to the ANGIN 5V we can make a circuit similar to Tweakie's one.
However we will have to change the logic of 16 PIN. When LOW it will switch off the laser and when OPEN it will switch ON the laser.
So this will probably just require to change command M11 with M10.
Does it make sense to you guys?