Force IEPE Sensitivity Units bug?

[geimerp]

There seems to be an error when trying to manually initialize an input Force IEPE channel, relating to the code used to choose the sensitivity units. I'm using the DAQmx Create Channel VI and manually wiring the required inputs, which has worked fine for a similar input Acceleration IEPE channel, including the code for sensitivity units.

However, with the force input, I get an error -200077: "Requested value is not a supported value for this property." The documentation specifies using 14891 or 14892 to indicate units of mV/N or mV/lb. So far, I have tried directly entering these unit codes both as an Int32 and as a listbox with unit labels corresponding to their code.

Adding to my confusion, the sensitivity units work fine when using the DAQ Assistant, with both unit options not causing an error.

Has anyone replicated this error or have a thought on what I might be doing wrong?

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NI 4431 - Labview2017

[BertMcMahan]

Please post a subset of your code so we can try it ourselves. It might not be the units themselves causing the problem.

Also, those DAQmx error messages typically give more info- they'll often say "Requested value is not supported", then "Value entered: XYZ", "Acceptable values: A/B/C/etc". If you post your full code we can try it out. Also, see if you can get more information from that error message.

As a last step, try making the code using the DAQ assistant, then right clicking and converting it to LabVIEW code. You'll then be able to see what it's doing internally.

[geimerp]

Burt,

Thanks for the quick and helpful reply.

The full error message is: "Requested value is not a supported value for this property. The property value may be invalid because it conflicts with another property.

Property: AI.Force.IEPESensor.SensitivityUnits
Requested Value: 14891
Possible Values: mVolts/N, mVolts/lb
Channel Name: force"

As you mentioned, it appears units may not be the problem. A subset of the code ("force...troubleshoot.vi") runs without error and can create the two input channels. However, that same subset included in the full code ("Discrete Swept-Sine..."), produces the units error.

Most helpful was your last suggestion to convert the DAQ assistant to Labview code. From that, it appears that the documentation is incorrect for the AI Force IEPE virtual channel. The DAQ assistant has sensitivity unit codes of [15891,15892], one digit off from what is listed in the documentation.

From the error message and this last finding, it sounds like the incorrect code I've been using (14891) corresponds to the code for another property somewhere else in the VI, causing the error when running it all together.