gear with BCD in/outputs...advice

[redrabbit]

I bought a precision decade resistor, but it interfaces.communicates and operates via BCD (binary coded decimal).
I have no experience with digital signals, but I think this is one of the most basic systems.
I'd like to find a way to operate this decade resistor, because it is (should be) very accurate...to 0.01%. I can find NO info or manuals on the unit, nor what it might interface with.

Julie Research Labs RD 105 M
Photos:

Front
http://i5.photobucket.com/albums/y17...t/DSCN3556.jpg

Rear
http://i5.photobucket.com/albums/y17...t/DSCN3552.jpg

Inside
http://i5.photobucket.com/albums/y17...t/DSCN3549.jpg


Click on this pic to see what I know so far...


If I supply all the circuits with +5v (on back panel), I can hear the relay clicks, and I am able to use the thumbwheel to read ohms, but only within a limited range (10k ??)..."program button" must be out (disengaged). No power = no resistance on the banana terminals.

Any ideas?

=RR=

[redrabbit]

Should (can) this thread be moved into "Digital" ??

Worse-comes-to-worse, I could install a rotary switch for each decade , to activate the relays.
I count 10 relays connected to each card, with each card being a "decade" of resistance.)


=RR=

[redrabbit]

I figured out how to use it without the remote digital BCD signals.
( I don't really need the remote BCD functionality anyways)

Before, I mentioned I had achieved limited range using the front panel when powered with 5v.
Well, that was at 0.5 amps, and that current is not enough to trigger all the relays. At 1.3 amps, the front thumbwheel switch works the full range, and is working well now.

=RR=