Sound logic breakout question

Hi all,

My machine control is wired so everything in the control is turned on and off through a main relay wired to the "Start" and "E-stop" circuit. When I shut down, it shuts the whole control down even the Mach2 breakout board.

I want to wire it so if the computer is off, the machine control cannot be started. I'm aware that output 4 is activated when the software is up and software E-stop cleared however, I have to start the control which energizes the B/out board so the output 4 would be energized. I'm wanting to add a solid state relay in the start circuit off of output 4. But I have to start the control to energize it. I dont want to wire the Breakout board seperate from the rest of the control. I like the fact that when I shut down, it kills everything.

Here is my question: I noticed with the control shut down and the PC running there is an LED in the middle of the board illuminated obviously receiving power from the LPT port. Is there somewhere on the board in this state that I can get a low voltage that is isolated from the LPT port to control a solid state relay that would in turn allow the control to be started?

So, if the PC is on I can start the control. If the PC is off the control Start circuit would be inactive. It would be nice if the PC on and Mach2 loaded and cleared were the only way the control could be started. Possibly an unused output pin at the LPT in Mach2? Or maybe just another switch/relay to turn the B/out board on first at start up?

Ron


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