Baffling Issue With Torch Not Firing When It Should And Firing When It Should'nt

Well Friends, I have managed to solve this problem -- with a lot of good diagnostic help from tommylight, PCW and the rest of you.  But, in the final analysis, two old sayings come to mind -- "Read the fine print on the board", and "When all else fails, read the documentation."  I posted a pinout diagram for the SainSmart ST-v3 breakout board in an earlier reply -- and in an inset box, right on the board, was the statement, "Invert P14 Relay in LinuxCNC To prevent the spindle from starting when AXIS starts".  That, of course, set me off on a search of the documentation to find out exactly HOW to invert an output pin.  It turns out that it is a parameter that has to be set with a "setp" statement.

It turns out that the whole problem is that on this particular board design the relay, Pin 14, is set high in hardware and you have to invert the pin to make the relay function properly (like most relays on the market).

These two statements, inserted in the HAL file right before the "# ---JOINT ASSOCIATED WITH THE Z AXIS---" comment:

setp parport.0.pin-14-out-invert TRUE
setp parport.1.pin-14-out-invert TRUE

were exactly what was needed to make the relays on both boards function properly.

The first thing I noticed after replacing the wiring in it's proper order, and powering on the machine, was that the "RELAY" LEDs were no longer lit -- that told me that I might be onto something.  Then, after starting the machine, I powered up the plasma and it did NOT fire.  I went on to run the cut-test program I have; aside from an immediate fault related to loss of ARC OK, it did fine -- I checked "Ignore ARC OK" and resumed.  It ran the whole program, firing when it should, and making some beautiful holes in this sheet of 1/2" mild steel on my table.  I will chase down the ARC OK fault later, when I have time.

So, again, thank you to all of those who offered help, suggestions, and possible causes/ solutions -- it allowed me to follow this to a successful conclusion.

John Carter
CCW Transport Services Inc
Grants Pass, Oregon