I've read a lot of information here, about controlling lasers, but I'm still very confused.  First, my setup may be different than most.  I'm running Mach3 talking to a UC100 motion controller attached to a Gecko G540.  There are limited pins available for the UC100.  I'm wondering what would be the best way to do TTL toggling using this setup.  Please be patient with me, I'm old and this topic is making me older by the minute. 

Jay

Jay,
If you connect your TTL laser driver input to your Z axis DIRECTION pin, you can trigger the laser on with a Z-0.x (negative direction) move in your gcode, and turn the laser off with a Z0.x (positive direction) move.  This may be the simplest setup to get you going.  You could also use the 4th axis if the G540 has one free (I don't use the G540, so not sure).  In this case you would set up the 4th axis as a 'C' axis, and use its direction pin instead of the Z axis direction pin.  This would leave your Z axis available for raising and lowering the laser to adjust focus.  This will work with the UC100 as I am using one in a similar setup with a laser diode.

John Champlain

Thanks for the info.  That is kind of what I figured.  The problem is, the G540 doesn't have the direction pin readily available.  I'd have to tap off of the pin in the UC100, before it goes into the G540.  Suppose it's worth a try though.  

Jay,
Here's a couple of items that make it easy to split out pins.  Found on eBay.  I have a setup for my experimentations.
John

Those are perfect, and they are on order.  Should have them by next Tuesday.  Thanks again.