Pinout for current loop interface

Noel Chiappa jnc at
Sat Aug 17 10:38:33 CDT 2019

    > From: Charles Morris

    > Is there any standard pinout for 20 ma current loop using a DB-25
    > connector, analogous to the well-documents RS-232 serial interface?
    > ...
    > Or would you recommend I use a different connector entirely? .. Maybe a
    > Jones 4-pin would make more sense.

I've never heard of people using DB25 for 20mA, at least historically,
contemporaneous with its widespread actual use. E.g. DEC universally used
'flat' 8-pin Mate-n-Lok connectors for 20mA serial connections.

Although I have the part numbers for both the male and female 8-pin shells,
they are no longer in production, and are getting hard to find.

Nothing precludes us from establishing a spec for 20mA via a DB25, of course
- especially if a set of pins can be found whih will not cause damage if such
a connector is plugged into an EIA connector by accident.

As 'idiot proof' engineering, I'd be inclined to use some other connector (no
suggestion from me as to what), but I can understand that people might prefer
to use DB25 (which everyone has, and are easy to find).


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