Fanuc PPR - Paper Tape Punch, Printer and Reader : Not quite working

[Chuck Guzis]

On 4/10/22 11:08, Martin Bishop wrote:
> Chuck
> 
> Thank you for the parallel port suggestion.  I followed it up by opening the D-25 and reviewing the wiring.  It looks very RS232 to me, the pin out I found is detailed in my 10 1314A Apr 22.  That the punch and reader respond to RS232 input I think settles the issue - I was briefly optimistic ...


No, not parallel port, but 20 ma current loop.   Used extensively in
teletype/industrial work.   Still serial, but suited to long-haul or
noisy environments.   The original IBM PC serial card could be
configured for CL.  The advantage is that it's not voltage-sensitive per
se, but rather to the current flowing through the loop.  On long hauls,
one could raise the voltage until the proper current level was obtained.
 RS232C, on the other hand is strictly voltage-sensitive.

https://en.wikipedia.org/wiki/Current_loop for details.

But it sounds as if you have a bog-standard RS232C setup.

Very old teletype setups used, I believe 60 ma. CL.

--Chuck