Cannot search by channel maximum

[Kenny_K]

I am trying to search for data using the data portal.  I choose the file I want (which has about 150 groups, with 7 channels each), and search for the group property (Pass/Fail) and then I am trying to search by a channel having a maximum value over say 90.  Search operation string is C1 AND C2 and C3.

I can search by channel name (aka HotPSI) just fine, but it will always show me zero results when ever I try to search for a max value.  And yes, the data does go above my maximum.

I thought that Diadem automatically added the max value when everything was indexed?  If I click on a channel, in the bottom right hand corner, it has a bunch of info on the channel, including the max and min.

I looked at the examples, and they have an example where you search for channels with a value above a level, and I was able to get results.  So I am not sure what I am doing wrong.

My file is saved during acquisition as a TDMS file.

[Brad_Turpin]

Hi Kenny,

This is a common point of confusion.  TDMS was built for speed, so the LabVIEW functions that create TDMS files don't do anything for you that isn't strictly necessary, unless you ask them to.  Calculating a maximum value for a channel that you are saving could slow down the acquisition, especially if you're saving many channels buffer by buffer in a continuous acquisition loop.  The Storage VIs and the "Write to Measurement File.vi" can both create TDMS files, and they DO automatically add "maximum" and "minimum" channel properties, which is confusing.  The "Write to Measurement Files.vi" was built for maximum ease-of-use, and the Storage VIs were built for maximum flexibility to read/write different file formats, and in both those cases adding the extra properties makes sense.  DIAdem also adds these and other properties when it saves channels from the Data Portal to a TDMS or TDM file.

The really confusing thing is that DIAdem also creates "minimum" and "maximum" (and other) properties when it reads data from any source (ASCII file, binary file, SQL data base...) into the Data Portal.  So if you're testing the contents of a TDMS file you created by loading it into DIAdem, you will see properties in the Data Portal that weren't in your file, guaranteed.

The best way to see what's really in your TDMS file is to use the "TDMS File Viewer.vi" on the TDMS palette.  It adds nothing and shows all properties with exactly the names and values that were in the data file (DIAdem and the DataFinder also display a few property names differently).

If you want to search on the "minimum" and "maximum" properties, you will first need to add those properties to your TDMS data files yourself.  I can send you a batch processing VBScript that uses DIAdem to do this, or you can build your own in LabVIEW.

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[AndreasK]

FYI: Just adding this link 'Searching on Certain Channel Properties Returns no Results for TDMS Files'.