[chbot] RS232 FILTER

[Marshland Engineering]

Just a note, I'm not actually communicating with the RS232 when I have a
fault. I download the program which takes 5 seconds and then the machine runs
all day. The fault come up as a X Y or S travel fault not often and not
repeatable.  The fault would indicate the encoder on the drive does not match
up to the linear scale. My gut feeling is I get a spike on the bus and I get
the error. Remove the RS232 cable, never get a fault. The earth loop sound
like the issue.