Random Stops Mid-Program

Hello All,
I've been really struggling with my machine recently. Currently it will randomly stop running in the middle of a program, as if the E-stop was hit. My breakout board has optoisolators, and I was having some trouble a while back where the limit switches would trip falsely. It seemed like the cause of that problem was excessive noise on my input circuits. I fixed that with capacitors across the inputs, and by setting up debounce. Now it seems like I'm having the same issue, but with the external E-stop circuit. I have a capacitor across the e-stop input too, but it is still tripping. What else should I look for? I watched the Hal monitor and tried to catch the e-stop tripping, but it must be too quick.

My question is, how much debounce is too much? I have the delay set at 100 currently, and it is better than it was at 20 and 50. Will going much higher affect anything else? Also, does anyone have any other suggestions on what might be the problem? Maybe it's not the input circuit at all... I'm only assuming it is because my machine was running great until I started having issues with the optoisolators.
Thanks in advance
Dave

That is one of the problems with 5VDC (although I do not know your machine, I suspect that you are using 5VDC for the logic).
If you use one of the Mesa boards (or others, I speak about mesa because I use them), you can go to 24VDC that is more industry standard, and much more noise immune.
I had similar problems with a VFD, that using a scope, reveled that simply the noise was too much for 5VDC. I tried all that I could, shielded cable, large distance from VFD ...

Thanks for the response. Yes, the input signals use 5VDC, though my board does run on 24VDC. I will see if there is a way to use the 24V for those signals.

Hi

In the past I have had similar problems on a machine with a 'dirty' DC motor, tripping the limit switches, just through noise.
No amount of shielding and grounding could prevent random halts.

I resolved it by powering the limits through a 12v walmart PSU, using that to energise a small 12v relay which held the 5v logic circuit closed

Worked and continues to work perfectly to this day.

Possibly consider a seperate power source too, to completely isolate from the rest of your system

regards

I think I've got this temporarily fixed. I had my external e-stop running through a second set of limit switches (extra safety in case the first set somehow failed. I cut those out of the circuit, so it goes straight to the E-stop button and back, and it seems to have reduced the noise on the signal significantly. I've had the machine running all day without issue.
Thanks for the tip - if I feel the need to put these switches back in, maybe I'll run them with a 24V relay. This seems to be working for now, though.
Thanks!