Tag Archive for: TDMS

iTestSystem Application: TestView Plus

Tach Signal in TestView Plus

TestView Plus is an iTestSystem application for quick and easy viewing and analysis of data recorded in .TDMS files.  Test engineers can open data files and then simply drag and drop data channels into a variety of graphs and tables.  Data plotting algorithms allow for viewing and zooming into even the largest data files without running into memory issues.

TestView Plus has many features that allow test engineers to manage multiple data analysis projects at once.  TestView Plus Sessions allow for fast transitions between data processing projects.  A Session retains the current tab and graph information, analysis files, and data workspace.  TestView Plus Windows and Tabs allow for quickly adding and ordering new and existing data views.  The TestView Plus Reporting Utility allows for simple customized layouts sized to fit neatly in a report or presentation.

Besides data viewing, TestView Plus also provides access to the iTestSystem analysis functions.  Data analysis can be performed on data in an active Time History graph.  To run an Analysis tool, select an icon in the Analysis toolbar or select an option in the “Analysis” dropdown in menu toolbar.  Once the analysis is performed, the results will be graphed in a new window.

How to Estimate iTestSystem TDMS Data File Size

When streaming high speed data over a long period of time it is important to estimate data file size to avoid filling up your drive and also to prevent producing large, unwieldy data files. I usually try to keep file sizes less than one (1) gigabyte (FAT 32 maximum file size is 4 gigabytes) to minimize potential data losses and to make sure data transfers, analysis, and plotting don’t take too long. Whether you are using the free version of iTestSystem to manually control data file size or the paid version to automatically control file size, it is important to estimate your file size before collecting data.

iTestSystem uses the standard binary TDMS file format to stream high speed data to disk. Estimating file size depends on five (5) things.

  1. Header Size (Negligible for large files)
  2. Number of Channels
  3. Data Type Size in Bytes
  4. Sample Rate
  5. Logging Duration

File Size Formula = ((Number of Channels) x (Data Type Size (bytes)) x (Sample Rate (Samples/Second)) x (Logging Duration (Seconds))) + Header Size

TDMS File Size Estimator Spreadsheet

File Size Example: Eight (8) Accelerometer Channels sampled at 2560 Samples/Second are logged as a double (8 Bytes) for 600 seconds to a TDMS data file. Estimated file size = (8 x 8 x 2560 x 600) = 98,304,000 bytes or 96,000 KB (98,304,000 bytes/1024 bytes / KB).

For more information about iTestSystem or file sizes, contact Chase Petzinger @ (844) 837-8797 x704.

Creating XLS files from TDMS Files

View TDMS files in Excel

TDMS Data file after import into Excel

Precision testing generates precision data. Acquiring, accessing, and analyzing these data files allows engineers and scientists to lower product costs, engineer time-saving solutions, and even save lives. National Instruments (NI) created the Technical Data Management Streaming (TDMS) file format for high performance data streaming and retrieval. This binary file is structured for easier sorting and access of the complex data within the file.

Collect TDMS files with iTestSystem

Are you looking for expert assistance understanding and manipulating TDMS data files? ITM has greatly simplified things with iTestSystem, its free custom engineering software platform that enables you to organize, acquire, view and analyze data. 

 Allow our experts to walk you through TDMS files or point you to our free solutions.

Before NI standardized on the TDMS data file engineers and scientists had to create their own high-performance file types. The TDMS file format is supported not only by iTestSystem, but also across all NI software.



In these instances, it is often easiest to export a TDMS file to a more commonly used file type like Microsoft Excel (XLSX).

NI provides a free program / plug-in that allows users to open TDMS files in Microsoft Excel. This means anyone can convert a TDMS file into an XLSX file and open it in Excel, and once there the file can be easily saved just like any other spreadsheet. Once saved as an Excel file, you can share, open, view and edit it just like any other XLSX file.


If you have installed iTestSystem Engineering Measurement Software, the TDMS Importer program / plug-in for Microsoft Excel is already installed. If not, then you can download the software here: https://www.ni.com/example/27944/en/

Once you have downloaded the NITDMExcel program by following the link and using the built-in installation wizard, you can save TDMS files as XLSX Excel files. To open a TDMS file in Excel, you can simply double-click the TDMS file. If that doesn’t work, you will need to right-click, navigate to “Open With”, and find the NITDMExcel program wherever you installed it on your computer.

TDMS File Right Click Menu

Right click on TDMS file to import file into Excel

Figure1: Right click on a TDMS file to import into Excel.

Each time you open a TDMS file in Excel, it will create a new workbook. Each workbook will have multiple sheets, one for the file properties such as the name of the test, date the data was taken, and more. The other sheet(s) will contain the data points plotted as part of the test, which would normally be used to create graphs in TestView Plus.

Now you can save the Excel and share it just like any other XLS file!

Related Links

Auto-Zero Utility Update
Wireless Strain Measurements with iTestSystem
Strain Gauge Installation for Field Testing

For more information about sharing data, iTestSystem Engineering Measurement Software, or test equipment rental, contact Ryan Welker @ (844) 837-8797 x702.