Mesa 5i25 Errors?

I am getting these smart serial errors sometimes on start up, and sometimes when using my e-stop. I have not been able to figure out a pattern yet. Any Ideas why?



Here is my config.

These indicate an electrical noise problem, likely a ground loop from servo/spindle drive to 7I77/PC
A ground loop from drives can sometimes generate enough HF current in the DB25 cable to generate
the 1.5V or so needed to cause a extra character error.

Possible solutions are:

Change PC ground so it comes from same source as drive ground

Use a common mode choke in the 7I77 analog outputs --> drive connections

If the drive has differential analog inputs make sure the 7I77 ground is not tied to drive
ground through the analog cables (if you use shielded cables ground the shield at the 7I77 end only)

Use a line filter on the Spindle drive and servo drives

Use a common mode choke on the spindle motor

Use a 7I77 isolator (7i77isol)

Make sure all contactors/relays have flyback diodes or suppressors

This machine had been working OK for a couple of years, then about 8 months ago it was taken out of service and relocated in our shop. (It was moved to make room for another machine.)

I finally got the time to finish getting it back running again last week. Things that have been changed on the machine since the last time it was working are, switched the monitor from a CRT to LCD flat pannel, and switched from running a single servo thread and PID (torque mode servos) running at 2.35kHz (as fast as I could make it go without getting real time alarms) to running a servothread(1kHz) + FP-basethread(5kHz) with a position loop pid in the servo thread and a velocity loop in the base thread (much easier to tune than the single loop was before.)

I'll check my grounding but I don't suspect any problems there.

I think the contactors/relays sound like the most likely suspects, since it is on opening or closing of relays in the e-stop chain that I'm seeing the alarms set.

Can fly-back diodes go bad? (I can't remember if when we set up the machine we bought relays with them built in or if we tried to size them so they wouldn't be needed.)

Diodes tend to be very reliable
I would guess this is more likely a grounding or lead-dress issue

lead-dress issue??? I'm not familiar with that term.

cable routing