How to open TDMS files without LabVIEW
TDMS is National Instruments' file format for measurement data, and LabVIEW is not the only way to read it. This guide covers the free options, a no-code desktop route, and a plain-language explanation of how a TDMS file is organised.
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Step by step
Understand what is in the file
A TDMS file is organised as three levels: the file, then groups, then channels. Each level can carry properties, which are named values such as a sensor name, unit, start time or test description. Channels hold the actual data, usually a long list of samples.
Option 1: NI's free TDM Excel importer
National Instruments offers a free add-in that lets Excel open TDM and TDMS files. It is convenient for small files, but Excel's row limit applies, so long recordings do not fit.
Option 2: npTDMS in Python
npTDMS is a free, open-source Python library for reading TDMS files. You can list groups and channels, read properties and convert to a pandas DataFrame, then write a CSV. It needs Python and a little scripting.
Option 3: DIAdem
DIAdem is NI's own data analysis software and reads TDMS natively. It is a full engineering tool and is licensed software, which makes sense if you already have it.
Option 4: Vizalyze
Start the 14-day trial of every feature and format (no credit card), then use Load to open the .tdms file. The group and channel hierarchy is preserved, along with the waveform timestamps and properties. Browse, plot and export to CSV without LabVIEW or code.
Groups, channels and properties in plain terms
Think of a TDMS file as a folder structure. Groups are like folders that collect related measurements, for example one group per sensor board or per test phase. Channels are the columns inside a group, such as a voltage or temperature trace.
Properties are labels attached to the file, a group or a channel. They store information such as units, sensor names and the start time and sample interval of a waveform. Time for a waveform channel is usually not stored as a column, it is derived from that start time and interval.
TDMS files can also be written in chunks over a long test, so a single channel may come from many segments. Good readers join those segments for you.
Which option should you choose?
If you have a small file and Excel, the NI importer is the quickest. If you like scripting or need to process many files in a pipeline, npTDMS is free and flexible. If you work in DIAdem daily, stay there.
Vizalyze fits when you want to look at the data first, compare runs and export or report without writing code. It reads TDMS through npTDMS, and it also opens the older TDM and TDX pair and LVM files.
Frequently asked questions
Do I need a LabVIEW license to read a TDMS file?
No. TDMS is a documented format, and free tools such as NI's Excel importer and the npTDMS library can read it without LabVIEW.
How do I convert TDMS to CSV?
Open the file in a tool that reads TDMS, choose the channels you need and export. With npTDMS you can convert to a DataFrame and save a CSV, and in Vizalyze you can export the loaded data as CSV.
Why is there no time column?
Waveform channels store a start time and a sample interval as properties rather than a column of timestamps. Readers rebuild the time axis from those properties.