Once upon a time, our company decided that we had a need for 1024 channels of relatively low-speed analog input.
After some discussion, NI sales recommended that we buy sixteen PXI-6225 multifunction DAQ boards, and sixteen SHC68-68EPM cables to be used on Connector 1, so that is what we bought. We are only using Connector 1, to get 64 AI channels per board. We decided, in the interest of simplicity of cabling and custom sensor PCB design to sacrifice (not use) all of the features available via connector 0, including an extra 16 channels of AI as well as the AO and digital capabilities. Our original intent was to reference the 64 signals to "AI SENSE 2" in NRSE mode, per published specifications. It all sounded good at the time, so we opted to purchase NI equipment for the first time, instead of our previous supplier's IOTech offerings.
Later, a couple of issues popped up:
(1) After our purchase, NI released an erratum stating that for NRSE (non-referenced single-ended) to work properly, we would in reality have to reference 16 of the 64 AI channels on Connector 1 to AI SENSE on CONNECTOR 0 !!! Oops, that would require an additional 16 cables and a complete redesign of our 16 custom sensor circuit boards and sensor chassis. Dare we give in and go with the less desirable RSE referenced single-ended mode?
(2) Just now I read that the SHC68-68 cable is the one recommended for Connector 1, not the SHC68-68EPM that was recommended.
Would anyone care to comment upon this sequence of events, and help us figure out the optimal resolution of these discrepancies?
Ted
