TDM File support in LabVIEW

[mrbean]

In one of LabVIEWs help links entitled File I/O with Binary Measurement Files, I found this little note:

Note  LabVIEW still supports the .tdm binary file format. The .tdm file format uses an XML-based format to store waveform properties and links to a binary file that contains waveform data. You can use the Read From Measurement File Express VI and the Write To Measurement File Express VI to read data from and write data to .tdm files. You also can use the Storage VIs to read from and write to .tdm files.

I was concerned about the word 'still' right at the beginning of the sentence.  It makes it sound as if there is talk of dropping support of this file format within LabVIEW.  Is there any cause for alarm?  We are just now looking into DIAdem as a possible solution for our post-test analysis.  Most of our tests are being written in LabVIEW.

[Brad_Turpin]

Hi mrbeam,

Wow, that does come off wrongfooted, doesn't it?  I haven't hunted down the original document you cite to check the context, but I think I can guess why that statement was made.  In LabVIEW 8.2 we introduced a new file format called TDMS and a suite of VIs to read and write those files.  While the binary footprint is different between TDM and TDMS, the meta-data schema (3 level hierarchy and name-value scaler properties at each of the levels) is identical between the two formats.  Basically, we created the TDMS file to give LabVIEW customers doing high speed streaming an option to get on the "TDM" bandwagon.  Both TDM and TDMS files are indexed and searchable by the DataFinder and can be loaded into DIAdem.

So I'm guessing that the statement was intended to reassure the customer base that the TDM file format is here to stay, even though we are introducing a new and very similar file format that streams to disk much faster than TDM.  The TDM file format certainly is here to stay, as evidenced by the fact that it continues to be the default file format for DIAdem, among other reasons.  It's too bad that a statement intended to reassure the reader actually achieved the opposite result.

Thanks for asking
Brad Turpin
DIAdem Product Support Engineer
National Instruments

[mrbean]

That's great to hear.  Now I can ask my next question.  We are developing LabVIEW (8.20) tests that are all being called from TestStand (3.5).  Can you point me to resources or offer guidance in the following.  We want to create our LV tests with TestStand and DIAdem in mind. If we can us thisTDM(S) format from the get-go in LV, then we minimize our effort during the post-test stage.  There is a great deal of unknown at this time, but one question in particular is if we want to customize the TestStand reporting (within the process model sequence files I assume), does the fact that we want to ultimately use DIAdem alter the approach we should take?

[Brad_Turpin]

Hi mrbean,

Well, we can discuss the details of TestStands steps interfacing with DIAdem later on, but the answer to your question is that if you choose to store your results in the TDM(S) file format, all you will need to pass to DIAdem is a file path (and perhaps a VBScript path), and DIAdem will automatically be able to access all the data you want it to analyze and report.  So using TDM(S) would greatly simplify the process of including DIAdem-specific steps in your process model.

Brad Turpin
DIAdem Product Support Engineer
National Instruments

[mrbean]

I'm using LabVIEW 8.20 and although it's extremely generic, I'm using a Write to Measurement File and saving to a file with a .tdms extension.  However, when I go to DIAdem (10.0), and I try to file::open, and I traverse to the directory where my file resides, the Files of Type doesn't list TDMS.  TDM file extensions show up, but to find the .tdms file I created, I have to select FIles of Type *.*.  After that I saw a number of dialogs about configuration files and plugins - I'm not sure what that's all about, but my real question is just - Why doesn't DIAdem 10.0 recognize .TDMS files directly?

[Patrick_P.]

Hey Mr. Bean,

I believe the problem you are running into is that the tdms dataplugin (what DIAdem uses to load files) is not currently installed.  Since the tdms file format came out after the release of DIAdem 10, it is necessary to download and install the tdms plugin.  I have linked the plugin here.  In general the easiest way to get to the dataplugins page is to go to www.ni.com/diadem, and then select on the dataplugins link on the left hand side.  Let us know if this adds tdms to the known file types.