Two separate adquisitions on a 6025E

[JoePerkins]

Hi,

I have a PXI NI 8175 with a 6025E card connected to two different modules: SCXI-1112 (thermocouples) and BNC-2090 (analog inputs) using a 182849A-01 cable. I can read thermocouples and analog signals from both cards, everything works fine, but I was wondering how is this possible. 6025E has only 16 analog channels but I can read 16 analog signals + 8 thermocouple signals, why? How does this internally works?

[AitziberH]

Hi,

this is because SCXI is actually multiplexing all the scxi channels to a single channel of the board.

No matter how many channels your DAQ board has, SCXI only uses one of them.So, you could have all the SCXI slots full with SCXI modules, each with up to 32 channels, and all these channels would work multiplexing to a single channel of the board.

[JoePerkins]

Thanks for your answer AitziberH,

I thought multiplexation could be possible, but does this mean any loss of information? Could I have 16 SCXI working simultaneously with full potential? Any documentation explaining this with detail?

[AitziberH]

The only thing that gets worse is the scan rate. You must have several things in consideration when using several SCXI modules, the final scan rate can change depending in factors such as the sampling rate of the DAQ board, resolution, number of modules, etc...

Here you have a document where you can see a description of this:

http://digital.ni.com/public.nsf/allkb/410A70C25A4D12B486256A1E0070BDAE?OpenDocument