On 4/10/22 12:23, Martin Bishop wrote:
> Chuck
> My error, you said 20 mA current loop, I bowdlerised it as parallel port.  I 
> have a punch with a parallel interface ...  I can't recollect ever using a 
> current loop interface on equipment, although I have met many in old 
> documents.  4 .. 20 mA current loops reporting e.g. pressure actuated 
> potentiometers are however old friends, if that is the correct term.  As you 
> observe current loop has good noise immunity.

There is a tie-in to parallel port, although somewhat tangentially.
Back in the 80s and 90s, CL was promoted as a long-haul solution to (as
well as other things) distant printers.  In particular, I remember Inmac
flogging them.


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