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usb 6215

I have a usb 6215 multi Daq. The analog voltage signals I am aquiring are jumping all over the place. My main concern is the signal for the motor current that is a current feedback converted into voltage. The voltage reading I am getting with a volt meter at the input is steady as can be, which I need it to be to accurately set a limit. But the voltage jumps all over the place in my VI. I have tried increasing the sampling rate in the daq assistant, using filters, averaging an array using a for loop, and using a mean, but it stilljumps all over the place.

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Have you verified the hardware? You may have a loose connection, bad grounding, poor cables, or a bad card. Run the test panel in Measurement and Automation Explorer. This will take LabVIEW out of the picture, allowing you to determine if the problem is hardware-related.

 

As far as your VI: get rid of the local variables. Your abuse of them has created multiple race conditions in your VI. LabVIEW does not execute code left to right or top to bottom or any other direction (except for property node elements). Use wires instead.

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Actually the way its set up, I need the program to interlock in order to run the rig, and because its running, I get a reservation error when I try to run max. I am going to have to figure out which DO is controlling the interlock so I can latch it then run the rig in max, its a weird set up that I inherited and am trying to fix so it works correctly.

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Hi Tavwtby,

 

I think you're on the right track here. As smercurio_fc has mentioned, making sure that your DAQ card is getting expected data in MAX is crucial for it to work as expected in LabVIEW. I would also try to remove those local variables in your code as they would produce race conditions, like smercurio_fc has mentioned too. When your VI executes, because of the lack of wires, you will never know when particular parts will execute.

 

Jason L.

Product Support Engineer
National Instruments
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