Differential Voltage Input with MCC USB-2408

[Hannamon]

Hi; does anyone have any LabVIEW examples of acquiring a voltage using a differential input?  I know I have to configure the USB-2408 first using the InstaCal.exe software for differential mode, which i've done already... But I'm not sue if I treat it as a single-ended program but using the differential channels instead (i.e. the pin numbers for CH0L/H).... anyway, some LV examples would be great.

[JRys]

LabVIEW doesn't care if the channel is set to differential mode; it just knows it must read that channel.

The programming examples can be found in ..\National Instruments\LabVIEW 2022\examples\ULx\. There are four LLB libraries in the Analog subfolder. Open Measure Slow Varying Signal and run the example named ULx Cont Acq&Chart Samples-SW Timed.vi. 

[Hannamon]

Ah, so it doesn't care if it reads CH0H/L or CH0/CH8, as long as it reads pins 1&2 then?  Now things are beginning to make more sense... and pin 2/3 need to be tied together by a 100k resistor, from what I understand... (I'm assuming this is the only case?)  In which case I would use "Read N channels, Single Sample" or something like that to get a single differential value out?

At any rate, I will check out those examples in the libraries you specified...

Edited May 10, 2023 by Hannamon

[Hannamon]

Also, assuming the " ..\National Instruments\LabVIEW 2022\examples\ULx\" refer to "C:\Program Files\National Instruments\LabVIEW 2022\"... in which case there is no "\examples\ folder... I have installed and reinstalled mccdaq.exe and instacal.exe... is there something else I need to install for this to show up?  All that I have is \resource\ directory.  Figured this out...

Oh, and the lvhlp.chm just contains a bunch of empty links...

Edited May 10, 2023 by Hannamon

[JRys]

Download the MCC DAQ Software CD https://www.mccdaq.com/Software-Downloads

Install InstaCal and the ULx for NI LabVIEW software. 

Once completed, go to Windows Program List->Measurement Computing->ULx for LabVIEW Help.

[Hannamon]

OK... didn't work right the first few times... t I modified the shortcut so that it not points to the correct file... and the CHM works properly now... I'm guessing that it's much easier to set up SE programs, whereas Diff programs need to point to the specific pins, and there's some math involved to read out the proper differential signal... because all these examples seem to be for SE measurements... unless I'm missing something over-obvious...