Different input voltage

[JuliusF]

Hello guys,

I have a problem, with my NI USB-6009. I try to measure a voltage of my wheatstone bridge, my multimeter says it´s 20mV, but my USB-6009 just says that it gets 1,34 V. 

Does anyone know how I can fix this problem?

Do I have to calibrate the USB-6009 or does it need a factor to multiplie the input-voltage?

[JuliusF]

Maybe it´s important to know , I´m using Matlab and just single ended measurement.

[santo_13]

Please share the exact circuit connections and also the source code.

Please do note that the accuracy of USB-6009 is typically +/- ~15mV

[Henrik_Volkers]

DMM:

Input impedance?  (>10Meg?)

Impedances to GND? (?)

6009:

Input impedance ?

Impedances to GND?

Impedances to GND of your  bridge supply?

Grap a instrumentattion amplifier (INAxxx) and build a Diff to SE buffer for the 6009...