NI 9215 - voltage swing-out

[froens]

Hi there

I'm fairly new to dealing with electronics, so please be patient with me.

I've bought a NI DAQ 9215 to read the voltage of two sources. The idea is to use voltage-two inputs in a .NET-program. The setup only requires to read the inputs every 3-5 seconds.

I have used the example-solution: AcqOneVoltageSample as boilerplate-code to test my setup (to see if I could read the inputs into a program).

It seems that the read-outs differ much from the expected results and alternate. I have used MAX to aquire read-outs and the phenomenon remains the same (see screenshot which is a read-out from a AAA-battery).

The read voltage alternates between zero and something near the expected value. Is there something wrong with my setup or am I missing a key-point in electronics theory?

Best regards

Frederik

[A.Rohde]

Hej Frederik

It is defenetly not something with Measurement Studio since you see the behavior in MAX as well. 

Could you tell a little about how the wiring is and send some screenshots from the MAX configuration?

For me it really looks like a loose connection. 

Did you solder the wires on the AAA battery or do you have it in a carrier? 

Best Regards

Anders Rohde

[froens]

At first I used a controlled voltage source but as it was fairly old I didn't "trust" its accuracy.

I have now tested it again with the voltage source, but experience the same behavior. I have attached a picture of the setup (note the voltage output). I have also attached a screenshot of the captured voltage from MAX.

- Frederik

[A.Rohde]

Hi Frederik

Thanks for the images, I need to see how you have configured the acquisition in MAX, so could you please send me a screenshot similar to the one I have attached below (where I'm doing the same thing as you are tying to on the same module).

Best Regards

Anders Rohde

Applications Engineer

National Instruments Denmark

[froens]

Hi Anders

Thank you very much for your aasistance.

I have attached a screenshot of my configuration. I see now, that you have requested this in a former message - I'm sorry I missed that part.

You mentioned that it might be a loose connection. I have changed the cables just to be sure (see second screenshot). The fluctuations aren't as regular with the new cables but they are still there.

As you might have guessed these screenshots were captured with a AAA-battery (the voltage source wasn't available at the moment).

Just to rule out any other misunderstandings I have attached a picture of the NI-component (with visible model number) and the cable-attachments (note that the cables, being both red, are marked to signal polarization).

- Frederik

[A.Rohde]

Hi Frederik

Could you give me a call I'd like to discuss this issue with you, more indept.

You can catch me (or my collegue Alex) on +45 45 76 26 00 (press 2 for support).

Best Regards

Anders Rohde

Applications Engineer

National Instruments Denmark