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Waveform properties missing in channels of TDMS file during run

I'm currently developing an application to read TDMS files in near-realtime and store them to our data platform for further analysis. The TDMS files we try to read are created using FlexLogger. During investigation of the files, I noticed that the Waveform properties that we require for our application are missing in the channels of a file that is actively being written to by a running FlexLogger app. Once we stop the run in FlexLogger, the properties are being added.

 

The properties that we require for our application are:

  • wf_start_time
  • wf_increment

Is this expected behaviour? Is there a possibility to add these properties to each channel at the start of a run instead of at the end? Or is there another way to add the start time and increment value of a channel to the properties at the start?

 

Thank you in advance! 

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This is expected behavior to write all the channel properties at the end. Since some of the properties aren't available until the end (i.e. min, max, average, monotony, etc.) we optimize the write by doing them all at once at the end.Logging some properties at the beginning can also be a challenge since different channels may have their first data available at different times and so the TDMS logger would need to check if the first sample and properties had already been written or not and this decreases the performance to continually be doing these checks until all channels have written their initial data and properties that can be written on the first time. I will pass this feedback along to our product owner and he can reach out to you with more questions if needed.

 

Thanks,

Brad

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