Get Started Reading TDMS File

R2026b

This example shows how to read data from a TDMS file into MATLAB® for analysis.

The TDMS file provided with this example contains sine wave measurement data for amplitude and phase. The measurements are in two channels, in the same channel group.

Inspect TDMS File Contents

Use the tdmsinfo function to obtain channel group and channel names in the TDMS file.

fileName = "SineWave.tdms";
info = tdmsinfo(fileName);
info.ChannelList

ans = 2×8 table
    1    "Measured Data"    ""    "Amplitude sweep"    ""    ""    "Double"    3500
    1    "Measured Data"    ""        "Phase sweep"    ""    ""    "Double"    3500

Read Data Properties from TDMS File

Use the tdmsreadprop function to view data properties from the file.

tdmsreadprop(fileName)

ans = 1×7 table
    "SineWave"    ""    2022-01-13 10:03:31.000000000    "Admin"    "Amplitude And Phase Sweep"    "01/13/2022"    "10:03:31"

Specify a ChannelGroupName and ChannelName arguments to view properties of a specific channel.

group = "Measured Data";
channel = "Amplitude sweep";
tdmsreadprop(fileName, ChannelGroupName=group, ChannelName=channel)

ans = 1×19 table
    "Amplitude sweep"    ""    ""    "DT_DOUBLE"    "Numeric"    "not calculated"    "Sine"    1    2022-01-13 08:38:35.674852848    2022-01-13 08:38:35.674852848    "t"    "not calculated"    1.0000e-03    3500    0    1904-01-01 05:21:10.000000000    "relative"    "Time"    "s"

Read Timetable Data from TDMS File into MATLAB

To read data into a timetable, derive the start time and time step, typically contained in the channel properties.

timeStep = tdmsreadprop(fileName, ChannelGroupName=group, ChannelName=channel, PropertyNames="wf_increment")

timeStep = table
    0.001

startTime = tdmsreadprop(fileName, ChannelGroupName=group, ChannelName=channel, PropertyNames="wf_start_time")

startTime = table
    1904-01-01 05:21:10.000000000

Using the start time and time step as arguments to the tdmsread function, read the data into MATLAB as a cell array of timetables. View some of the data from first channel group.

data = tdmsread(fileName, StartTime=startTime.wf_start_time, TimeStep=seconds(timeStep.wf_increment));
ttData = data{1};
head(ttData)

                Time                 Amplitude sweep    Phase sweep
    _____________________________    _______________    ___________

    1904-01-01 05:21:10.000000000           0                   0  
    1904-01-01 05:21:10.001000000           0            0.063418  
    1904-01-01 05:21:10.002000000           0             0.12658  
    1904-01-01 05:21:10.003000000           0             0.18923  
    1904-01-01 05:21:10.004000000           0             0.25112  
    1904-01-01 05:21:10.005000000           0               0.312  
    1904-01-01 05:21:10.006000000           0             0.37163  
    1904-01-01 05:21:10.007000000           0             0.42975  

Use a stacked plot to visualize the relationship between the data of different channels.

stackedplot(ttData);