How to call tdms file in DIAdem programatically using LabVIEW

[Jothirajalingam_SS]

Hi all,

           I'm working on a project which has to acquire and stamp data in every 5 ms and store the data from the test cycle start up to almost a months' time. We have decided to store the data in the TDMS file format. We are going to use DIAdem for report generation. I'm new to NI diadem. So I need to know whether it is possible to acquire at the rate of 50Ks/s of around 15 channels and store data to the TDMS file and how we can call a TDMS file into DIAdem and generate reports in the HTML format.

[Brad_Turpin]

Hi Jothiraja,

Yes, I think this is an excellent choice.  In DIAdem you can just drag and drop the TDMS file from the NAVIGATOR tree view on the left into the Data Portal on the right in order to load the TDMS file.  The REPORT panel in DIAdem has a "File >> HTML Export..." menu you can use to export your configured report in HTML format.  Both the data loading and the HTML export can also be run programmatically in DIAdem, if you need to automate the reporting process.

On the LabVIEW side, how large is your acquisition buffer going to be?  1000 values on each of the 15 channels?  5000 values on each of the channels?  If your acquisition buffers are going to be smallish, then you may want to consider creating a "NI_MinimumBufferSize" property on each of the 15 channels, assigning a value to this property that is the number of channel values you want to flush to disk at a time.  The question here is how much of the resulting TDMS file will be stored data vs. binary buffer header information.  If your resulting TDMS_Index file is tiny compared with its TDMS file, then you can ignore this tip.  Alternatively, you could run the "TDMS Defragment.vi" at the end of the data acquisition, or equivalently load the acquired TDMS file into DIAdem and then re-save it over the original.  In both of these cases you will get just one binary buffer at the top of the TDMS file, and all the rest of it will be stored data.  Again, you can compare the size of the TDMS file with its TDMS_Index file to show you what the effect is.

TDMS is plenty fast enough to stream the 15 channels at 50kS/s that you propose, and I believe you will be very happy with the choice of TDMS as your file format and DIAdem as your reporting engine.  I'll also be happy to help you through whatever obstacles you may run into along the way.

Brad Turpin

DIAdem Product Support Engineer
National Instruments

[Jothirajalingam_SS]

Hi Brad,

                    Thanks very much for the information.

 Jothirajalingam SS

Sriram Automations, Chennai.