Write to measurement file loses timestamp data in tdms format

[bpt2016]

Hello all, I'm using the Write to Measurement File expressVI and I have created a loop in order to be able to individually label the column headers for each data signal that I'm writing. However, while the loop is successful in doing this the resulting TDMS file that the expressVI creates ends up losing the timestamp data that is used to record the time for each row and just writes a '0' instead. The timestamp data is present before the loop that adds column headers, which I have verified by adding an expressVI just before the loop. Please see the attached code for clarification. 

How do I regain the timestamp info after the for loop executes and adds column header info? Thank you. 

[Bob_Schor]

The problem with Express VIs and with the Dynamic Data wire is that they (almost) complete obscure what is being done "under the covers".  They manipulate data in ways that are unseen and often unexpected.  While they allow beginners to do extremely simple tasks quickly, they can easily lead to situations such as you are discovering.

If what you want to do is to write a TDMS data file, you should probably investigate the TDMS functions on the File I/O palette.  I've not used TDMS myself, but I know there are examples and documentation in the LabVIEW Help.  I suspect that if you do go with straight TDMS, you will probably save yourself further problems by not bundling your four inputs into a Dynamic Wire, but making them a 1D Array (or possibly a Cluster).

Bob Schor