I have a PROMA THC on my home-built plasma machine (with MACH3) and it has been working flawlessly for several years.  I come out to the shop today and despite the PROMA clearly telling the torch to go down it instead goes up, eventually losing the arc.  Nothing has changed in the programming or hardware recently, what could be causing this?  Ground is good, I can't find anything in "Ports and Pins" that looks amiss.  Anyone have any ideas?

Thanks

Dale 

Check the two LEDs OEM code 37 and 38. They are indicators of torch UP and torch down input signals.