Can I save a TDM file without its TDX data?

[SRH_UTAS]

I have hundreds of data files that have been sorted (by date).  In certain cases, I want to analyze subsets of this data in particular groupings.  I would like to save these groupings in a TDM file but I don't want to another copy of the bulk data.  However, I notice that if I save a TDM, it automatically saves the TDX, and I'm not sure it's possible to save/open a TDM without its same-name TDX file.  Does anyone else have a similar need and/or know of a data management method that can suit my need?

Thanks.

[Walter_Rick]

Hi SRH_UTAS,

A TDM file always contains a TDX file for the bulk data. But if you use the DIAdem command DataFileCopy you don’t need to worry about the TDX file. It will be copy automatically the TDM file and the associated TDX files.

Alternatively you can convert your data to TDMS. That’s just one binary file which contains all information of the TDM and TDX file and is based on the same TDM data model.

Greetings

Walter

[SRH_UTAS]

Hmm...  But it seems that the TDMS file simply puts all the information in a single file and, in the end, is almost as big as the TDX file.  What I'm trying to do is only save the meta data but not the bulk data, since I already have a copy of the bulk data in another set of TDM/TDX files. 

Maybe I'm asking the wrong question.  Here is a simplified example of what I'm trying to do:

I have several (let's say, 6) original TDM files.  Each of these original TDM files have 20 or more channels.  I've created a new TDM file, pulling out only 5 of the channels from each of the original TDM files but organizing them into 6 groups corresponding to the original 6 TDM files.  From this new TDM file, I've created a TDR file where the plots are based on the 6 channel groupings.  Due to this TDR to new TDM association, I think I need to save the new TDM.  However, that means I now have a new giant file that contains duplicate data from the original TDM files.  I don't want this duplicate data.  Being very new to DIAdem, maybe I'm just going about this the wrong way because I haven't figured out the "right way" to accomplish my needs.  Can anyone advise?

[Brad_Turpin]

Hi SRH_UTAS,

It sounds like you want to be able to create a number of TDM header files that each point to a single existing bulk TDX data file.  Did you know that there is a TDM Header Writer DLL, which is also wrapped up in LabVIEW commands, if you prefer graphincal programming.  The only trouble is that you'd have to know the details of how each data channel is stored in binary in the TDX file, and you may not know that.

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[AndreasK · Accepted solution]

Even if there are technical ways like Brad describes there is nothing directly build in mechanism to implement your use case.

What you can try to do (if possible) is using datafinder to define your new file as a query and load the query results instead of an tdm file.

• Find a query that contains the contains the channels you want to load:
  e.g. channels where channel.name is 'abc' or channel.name is 'def' and root.creationdate is ...
• Load the result of the query into data portal
• You can save those queries as tdq file and use those to define your resulting tdm file/portal content

The result is almost equal because if you are going to delete tdm files you assembled tdm file would be invalid and the query would return less channels.

[StefanR]

This sounds like a cool idea!

[SRH_UTAS]

Thanks, Andreas.  It's almost what I was looking for.  Anyway, I learned something new!

[Basil-B]

Hi SRH_UTAS,

It sounds like what AndreasK suggested would be the right way to go because otherwise you'd have to modify the header file every time you changed or removed a TDX file. You could also do a combination of both depending on your particular application.