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Wrong measurements using NI9207 with cDAQ9189 for voltages

I’m using the NI 9207 in cDaq 9189. I’m trying to use two channels at the same time (I0, I1) for voltage measurements. The measurements for the voltage channels aren't exactly what we expected. We are testing with a multimeter using a known source and It exists high variation between NI-Max and multimeter readouts  (For example Multimeter: 4.9284V - NI9207: 4.7030V)

 

We have tested changing slots and channels, obtaining same wrong readouts.

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How did you read the voltages?

DMM have a low pass filter included.. 

How does the signal look like when you use high sample rate (2ms, maybe one channel only) and capture 100 ms .. 50 samples?

 

If you use a 9V battery ... directly connected how does is compare?

 

Greetings from Germany
Henrik

LV since v3.1

“ground” is a convenient fantasy

'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'


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Now, I'm testing the NI9207 using the NI-MAX creating a task and I'm comparing with multimeter for checking accurency (the voltage source I'm using is a battery).

 

I already got right measurements using the wiring.JPG configuration, but I have to use a 1M resistor for each voltage channel. Is there any solution for avoid this scenario.

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