[Linux UL - error in differential voltage with USB-1608G]

Thanks for the code.

I consistently get +0.9988 @ 1.0V

I get +0.6988 @ 0.7V
and +0.4987 @ 0.5V
 

[Linux UL - error in differential voltage with USB-1608G]

Hi

I've just tried again. I made the edits to the example, see attached. I applied 1.0V and the value reads low still.

I am using channel 0 with a 100k resistor between the low and the ground as instructed.

I also edited the Python code example with the same result. I'm using OpenSuse 15.4.

Can you suggest anything I might be missing?

Thanks

AIn_dif.c

[Linux UL - error in differential voltage with USB-1608G]

Hi

I'm using a USB-1608G and I connected a voltage device in the differential set-up. I installed the Linux driver.

I adapted the sample code 'AIn.c' to work for differential voltages by setting:

    inputMode=AI_DIFFERENTIAL;
    range=BIP1VOLTS;

However, the voltage reading is low. If I apply 1.0V I read around 0.998V. This uses the ulAIn function.

If I plug the device in to a Windows laptop and read the voltage using DAQami I get 1.0V.

Also, I adapted the sample code 'AInScan.c', which uses the ulAInScan function, to read differential voltages and this gave approx 1.0V.

Is there a problem with ulAIn voltage reading? Perhaps I am missing a required setting? Why does the ulAInScan give a different (and correct) number?

Thanks

Matt