Compumotor Parts

I once bought a similar collection from a firm specializing in
motion works for assembly and packaging plants. These boards
appeared to fall into two general types, the first receiving ascii
strings from a controller of some kind and outputting TTL step
and direction signals, and the second board type amplifying these
for use on stepper motors. As I recall, the ascii strings included
setup commands specifying full, half, microstep; and strings that
approached G-code power - step 3,000 steps along the whatever
axis.... (My memory may be faulty at this point....)

Some were designed to accept RS232 cables directly, others
had ribbon cable headers. Some had on-board power supply
components, others had terminal strips for individual voltage
supplies.

I cannot comment on whether the firm stuck with their somewhat
proprietary (non-G/M code) arrangement, but they seem to "own"
much of a market outside the machine tool business, so it wouldn't
surprise me to see their arrangement as a de facto standard of some
kind...

I have long since lost the manual reprint I once had, or I'd volunteer
it.... / mark