TDMS List Contents error code -2532 bug?

[abvenk]

Hello,

I'm using LabVIEW 2016. I've been trying to use the TDMS List Contents function to input a known group name and output the channels in the group. While I get the group output and channel output, I still get a warning error code -2532. The explanation is that the group/channel name is invalid. However, I do get the correct group and channel names as output. I don't understand why the function still throws an error code if it is already giving me the right output.

The reason for this question is that I'm using a case structure with T/F condition for error code -2532 to handle non-existent group names. 

I also made a unit test for testing out the different values of group names. Weirdly, the unit test works as expected, i.e. when I feed it a non-existing group name, it runs the error handling case. 

Is there something happening with the string input? The characters match 1:1 between input and output, but could there be "ghost" characters being padded onto my input string at some point? How do I detect/correct "ghost" characters?

Thanks.

[Carolynn.V]

Hi abvenk!

Can you upload a screenshot of your code to help us understand the problem you are encountering? 

Does the TDMS file have channels existing in all groups before you call the TDMS List Contents function?

Thanks,

[abvenk]

It's hard for me to upload a screenshot because the function is embedded in subVIs and I wouldn't be able to upload the entire code. 

However, I replaced the TDMS List Contents with the TDMS Read function, and I got it to work as I wanted. The key difference between TDMS List Contents and TDMS Read is that the -2532 code shows up as a "real" error (with a red cross) in TDMS Read. But in TDMS List Contents it shows up as a "warning" (no red cross) which may be the cause of the weird behavior. Maybe the warning isn't implemented as rigorously as the error?

Nothing else changed in the TDMS file or my code when I replaced the List Contents with the Read. Also, to your question, yes the TDMS file has channels in all groups. 

Thanks.

[Carolynn.V]

I'm glad changing the function solved your problem! You are correct that warnings and errors are handled differently in LabVIEW. 

[billko]

I think a CAR should be filed because two VIs from the same package should not throw the same error as an error in one VI and as a warning in another.

[Carolynn.V]

Thanks for the feedback, I'll look into it!

[abvenk]

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@billko wrote:

I think a CAR should be filed because two VIs from the same package should not throw the same error as an error in one VI and as a warning in another.

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What is a CAR?

[billko]

Corrective Action Report - a bug filing.