CTRIO Reset on arc start

[earendall]

I am working on a automation project that contains motion using steppers and a TIG welding process. When the TIG welder starts its arc using a HF arc start, the millisecond the arc starts both of the CTRIO modules seem to reset and the red error light blinks. After the arc has established, the modules work fine, but this reset causes the motion to cease and messes up the weld process. I have tested this with the welder off and the machine behaves normally.

The questions I have is, could this be ambient RF entering in the PLC somehow, or could it be coming in on a wire into the module?

I am using a DL06 PLC with AD STP-DRV-6575 stepper drive, STP-PWR-4810 power supply and the AD stepper motors. I will add that this is in bench testing and the system is open. Im curious as to the most likly entry point so when we install in in the enclosure, we ground everything possible.

Any input is welcomed to hedge this issue off before we commission this machine.
 

[Greg]

The impulse created when the arc starts is a broad spectrum disturbance. Absorbing this to ground and preventing it from getting into the low voltage wiring of the PLC is what's important. If the CTRIO module is resetting with the RED LED blinking, then the disturbance is clearly on the logic side of the PLC. This means additional filtering on the PLC power input lines might help. We suggest using an AC line mains filter such as the Schaffner FN 2010-1-06 which is mentioned in our CE document. Shielding might also help if it's radiated noise coming in.

[earendall]

The PLC is powered via a SOLA 24vdc power supply. Do you think this is not providing enough filtering to the AC mains?
Thinking of this as a PLC logic side issue, I wonder if its coming in through one of the prox switches that are near the torch.

Thanks!

[rlp122]

It may be grounding.  I have seen a lot of this sort of thing happen with poor grounds.