Can I find a wiring diagram for a SCSI cable?

[kcillini77]

I have a PXI chassis setup that includes an NI-2501 multiplexer and another card that both use a 68 pin SCSI output.  However, we also need to T off some of the signals to yet another card.  We bought a 2 meter cable from National Instruments, part number 183432B-02 with the intention of cutting into it, finding the appropriate wires, and creating a new cable.  But we were surprised to find 43 twisted pair of wires in for a 68 pin device.  As we determine continuity with the pins, we are finding some duplicates and some that seem to be tied to nothing.  I can't find a schematic for this cable anywhere.  Is there one that could be shared with me somewhere?

[WeeMac]

 Not sure if this helps, here is a 68 pin SCSI pinout diagram as per SCSI-3.  

http://pinouts.ru/HD/info-scsi_pinout.shtml

http://pinouts.ru/HD/scsiexternalhidsub68diff_pinout.shtml 

[Jason_D]

In this KnowledgeBase Article you can see which pins are not connected.  I hope this helps!

[Jason_D]

As this document mentions you might want to use the NI SH68-68-S to get access to all of the pins,  as the cable you are using was meant for different devices all of the pins might not be available.

[kcillini77]

Jason,

Thank you.  Both pieces of information you posted are very helpful.  We don't have our solution yet, but we're a lot less confused now!