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tdms log file - TDMS: Warning: Tried to append flags .....

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I have a Diadem script which opens text files, does some operations and saves them as tdms data files.  However, some of these files end up with an associated log file, which contains the message: -

"TDMS: Warning: Tried to append flags to 'Processed_Data.DateTimeCorr' which is not supported in 'tdms' file format! Flags are ignored!"


I have been unable to find out what this means or why the log file is created.  If I manually load the data file, then the log file disappears.  The data file itself looks ok.

The channel, 'DateTimeCorr' is a time channel.  I am using Diadem 2017


Any help in understanding what is going on would be appreciated.




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In DIAdem there is the ability to set a value of a channel to NOVALUE.
If a channel has NOVALUES in addition to the values a flag is stored in the DIAdem TDM files.


This means Processed_Data.DateTimeCorr has such a NOVALUE in it.


When would you see a difference?

  • Date/Time channel would get a currious value if loaded with LabVIEW
  • If file has real int channel (no double) and a value is marked as NOVALUE this will show a number after loading.

So this logfile entry is just pointing to an effect that normally does not matter.


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Hi Andreas,

Thanks for the fast response.  I found NOVALUES not in the data, but rather in the properties of the 'DateTimeCorr' channel.  The max, min channel properties were given as NOVALUES after running the script.  Using 'Call ChnCharacter("DateTimeCorr")'

seems to fix the issue . 




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Accepted by topic author mrme

Hi mme,


The most likely reason this happens is that you are setting flags in the VIEW panel before saving the data to an external file.  The TDM file format will actually save your selected flags as a sidecar invisible channel next to the actual data channel.  It's usually a feature when saving to TDMS that you don't get this extra information, which is usually just a really big array full of zeros that you never use again.  I usually programmatically delete the log file after saving the TDMS file in cases where it can get created.  The log file can also tell you when a load or save operation encounters trouble, so there are cases to keep them around.


Brad Turpin

DIAdem Product Support Engineer

National Instruments

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