random smart serial errors

Hi

A friend of mine is expieriencing rare smart serial errors, communication errors.

I attached the error message. I am guessing it may be an EMV Problem.

This guess is because the first time we experienced it was when we connected the 7i77 by a flat cable directly to the inner port of the 5i25 and then started the milling motor.

By changing to the outer port and the regular printer cable the error vanished - but now it is back.
It doesnt seem to happen anything, the attached error message turned up while he was milling a large program. It completed without any problems.
But then later LinuxCNC crashedwith the attached errorlog while it was doing nothing? Segfault in a crypto library?

How can the smart serial communication error be traced?

best regards

Hard to tell unless you solve the other crashing problem, but if you get sserial errors with spindle operation,
this is a pretty sure sign of a ground loop. What this means is that you have enough high frequency current flowing
down the parallel cable to generate about 1V of difference in the ground reference from end to end;
Possible solutions are line filter(or common mode choke) on spindle drive,
common mode chokes or ~100 ohm resistors in series with analog out and GND wires to drives.
(if drives do not have differential inputs)

There are other options to select once the noise source is found