Convert TDMS to CSV

Drop a .tdms file here, with its .tdms_index if you have one.

The file is read in this browser tab. It is never uploaded.

Not supported: DAQmx raw data, ExtendedFloat and FixedPoint channels, arrays of dimension other than 1. They are reported, and the rest of the file stays readable.

How it works

Drop the .tdms file above. It is read in this tab and never uploaded.
Check the channels on the plot. What you see is what will be exported.
Press Export, keep or untick channels, and save the CSV.

What the CSV contains

One file per group, one column per channel, with the channel name and unit in the header.
A time column in seconds from the waveform properties (wf_start_offset and wf_increment), or the sample index when there are none.
An optional column of absolute time in UTC, from wf_start_time.
Every value as stored in the file, never rounded. Channels shorter than the others leave empty cells.
Text values that start with =, +, - or @ are prefixed so that a spreadsheet does not run them as formulas.

Large files

The export is written block by block, so the whole file is never held in memory. Long channels are split into numbered files of 1,048,575 rows by default, the most a spreadsheet can open; the limit can be changed. In Chrome and Edge, Export to a folder writes the files straight to disk.

Files other tools refuse

Interleaved and big-endian files, files with several chunks per segment, and files cut short by a crash of the test bench are read. What cannot be read is named, with its segment, and the rest is exported.