Hi,
I am assuming you have your laser power supply wired as the diagram (with WP connected to GND through the water flow sensor). Connect the laser TTL(L) and GND to your breakout board. Configure Mach3 to set Output#1 to Pin17 (Active Low).
Now the Gcode;
X0
M11P1
X1
Will turn the laser ON
and the Gcode;
M10P1
X0
Will turn the laser OFF.
(The M11/M10 commands are required to be followed by an axis movement – that is the only reason for the X0, X1 in the above example).
In a few weeks time, once you have this all up and running and are familiar with your laser use then you can incorporate the PWM laser power control. My suggestion for PWM control is described here;
https://www.machsupport.com/forum/index.php?topic=12444.msg265104#msg265104Hope this helps.
Tweakie.