Hi,

I've been tracking through dozens of forum posts trying to debug this issue.

I'm setting up mach3 to control a plasma table. This is something I bought from an estate sale, and am refreshing from the original owner (no longer with us).

I'm currently using mach3 to control a mini-mill successfully with a gecko g540.

For the plasma table, I'm just swapping the parallel port cable over.

It's using this bob: https://www.omc-stepperonline.com/download/ST-V2.pdf  (or some clone).

But before I even get to that specific hardware, I'm setting up mach3 to use port 1, pin 17 for output 1 to fire the plasma torch. It should be the relay activate pin.

When I toggle "torch on" with f5, in the diagnostics output, I see output 1 flash on and off. However, I do NOT see any of the parallel port pins light up to indicate output 1 is sending a signal out the parallel port.

1) Should I see the diagnostic parallel port "pins" light up? How else can I confirm that output 1 enabled is in fact enabling pin 17 output?? This is my main problem.

2) The relay enable jumper is connected on the board. A continuity tester indicates no change or closing of the relay when output 1 is firing. I have not yet checked the voltage to pin17 on the parallel cable while toggling yet but I will, to confirm its not a bad relay.

3) I do have 12v supplemental power hooked up to the board. xyza axis are all moving correctly. input limit switches are all properly signalling and I see them light up the parallel port pins in diagnostics with a yellow indicator.

4) I have tried various combinations of enabling and disabling spindle motor output with step/dir on port 1 pin 1/0
Under spindle setup, I have tried various values for period /min %. I'm currently using 7 / 5. As I said, I do see output #1 flash on and off in diagnostics.

It is my understanding that output 1 is supposed to just go active (and for me, fire the relay to start the plasma), and the pwm for the spindle should be controlled separately, not on pin 17. Please confirm this is correct?

5) I have also confirmed my wiring to the plasma torch is correct. If I jumper across the terminals of the relay, the plasma torch fires correctly. I simply can't get mach3 to output the correct signal to the relay to close it. Again, I will confirm its not a bad relay by checking pin 17 voltage.

As an aside. it would be REALLY good in diagnostics to somehow show what output1 is firing when it blinks indicating it is active (or to see the current in memory mapping of an output to pin/port based on read configuration values. This would tell me if some other configuration somewhere is screwing up what I have output 1 mapped to, or otherwise tell me why pin17 is not lighting up on my parallel port diagnostic when I have it mapped there.


Thank you!

Update: After checking the voltage from pin 17, I am in fact getting 3.25 volts. I seem to recall something about this being a problem, and that old parallel port standards were based off 5 volts. I'm not sure if this is the issue, but I at least have an idea that it may be.

I'm very curious to understand why the diagnostics view is not showing pin 17 lighting up when output 1 is on though. It makes for a very non-intuitive diagnostic window.

One thing I hate is when someone asks a question, then posts I solved it, and then says nothing else.

I solved it.. I needed to plug in usb to get power to the 5v relay that switched on spindle control. I thought that the 12v supplemental power supply did that, but nope. It works with the USB plugged in for (more) power.

So in summary: I have my db25 plugged in. I have a usb cable plugged in, and I have a 12v supplemental power supply plugged in. The 3.3v pci seems to work.