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.tdx failed to create .tdm

I have labview running data acquisition with a thermal chamber and LVDT to generate change in length values with respect to temperature.  I ran the program for approximately 2 days with a data save every 30 seconds.  I noticed that while labview is running it does not create the .tdm file but does fill the .tdx file.  Once the VI is stopped, the .tdx is converted into the .tdm.  

 

 

My .tdx file was rather large (almost 20 GB) and spent a long time trying to convert to the .tdm, which, it failed to do.  Is there a way that I can try this conversion again?  Is the the data that I have stored away in my 20 GB .tdx file useless?  I really hate to throw away 2 days worth of good data.  Thanks!

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Hi,

 

This thread is discussing a possible solution.

 

 

 

Christian

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Lets try to explain what is happening here.

 

  • The tdx file only contains the binary data of the measurement. The channel data. Which channel exist and where they are stored is written in the tdm (xml) header file.
  • The tdm file is not perfect fit for streaming because channel data has always be aligned in one piece.
    To make this work the channels are moved in the tdx file while running measurements in append mode.
    This causes the tdx file to contain empty space when your measurement finishes.
  • When calling Save following sequence is done
    - Check how much dead space is in the tdx file. If the amount of dead space to used space is bad the tdx file is rewritten tdx~
    - after rewriting the tdx file the tdm header is written pointing to the data sections inside the tdx file

So in your case the tdm header files didn't show up. Did you stop it because it lasted to long or did it fail? (missing storage place?)

Because of that it is not possible to reconstruct the tdm header.

 

Maybe you can switch to tdms (s = streaming) file format. If you use the storgae vi's you have to make sure calling Save once after your first shot measured.

Afterwards the tdms file should grow like the tdx file did. Even a switchof of your computer should leave those file intact till the point where they where written.

Maybe you can think of switching to the native tdms API that better fits streaming jobs.

 

Greetings

Andreas

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Thanks Andreas!

 

I stopped the program because we felt we had gathered enough data but it somehow ran into trouble and I ended up with the empty .tdm file.  I will look into the .tdms file though as I have more testing to do.

 

Oh, and thanks to Christian for the link to the other thread.

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