[chbot] RS232 FILTER

[Marshland Engineering]

I have a CNC mill with a RS232 port. If I leave the cable connected to the
pendant, any spike in the workshop upsets the CNC control. Turing some things
on or welding etc. It is 40 years old so the internal caps may be a bit dogy.
I was wondering where I could find a filter off the shelf (too many other
projects to make new) that I can put in the line. Maybe something I can easily
modify. It only works at 9600 baud so low bandwidth.  

Cheers Wallace