I have to use the 'space' and 'alt-R' hotkeys to make the machine wait for my outboard THC to do its thing. In the port and pin setup all seems right. The diagnostic screen shows the input #1 and #2 active when I test the relays but it has no effect on the feedhold. The actual keys work fine. Perhaps there is an easier way to do this than feedhold and start but I haven't found it. Any clues?

I can't make the feed hold do anything useful either.
If you resume, it seems to rapid to the end of the vector that was pause. Not resume at the feed rate. Try that on a circle ! -- Crash..!
My workaround, (which is not a solution) is to go to single step and just finish the vector.
Not sure how you would make the torch go off, but I note the compoud goes off at the end of the single step cycle.

caveat: If the next move is a G0 (rapid) then it gets done at the feedrate instead of the rapid rate.

workaround: Every rapid line needs a G0.

The space bar pause does not work correctly, and with a USB keyboard is usually TOO LATE. I use the PS2 kb-plug.

It would be nice if you could resume with Alt-R after hitting CYCLE stop which is more like cycle ABORT (script terminated is the message), and pause which is BLOCK abort.

Wouldn't it be nice to have a branch instruction in Mach3, or have I missed something? Subroutines, but no branch? How hard is that?

I get the responses I want from the keystrokes. I just can't get the dang 'alt-R' to resume the operation. I have tried three different software packages and each one has a quirk or omission that makes it pretty much useless to my application. Maybe the Burny and Vision prepackaged controls aren't such a bad deal after all. At least they have everything you need, including technical documentation.

I enabled safety on input #1 in general configs and now when I input to (in my case) pin 12 I get a hold with the torch still enabled. That's what I wanted. Too bad it has a small delay in it. Doesn't bother what I am doing but it just shouldn't be there. Kinda dumb to use a safety circuit to control, anyhow.