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Read Multiple TDMS Files into MATLAB

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This example shows how to use a TDMS datastore to read data from multiple TDMS files into MATLAB® for analysis.

The multiple TDMS files of this example contain measurement data of a sine wave amplitude and phase, based on a trigger.

Read Multiple TDMS Files at Once

The tdmsDatastore function creates a datastore object, which allows you to treat all the TDMS files in a folder as one dataset.

folderName = fullfile(pwd,"Trigger");
ds = tdmsDatastore(folderName);

Review all the channels in the dataset. 

ds.ChannelList
ans=2×8 table
    ChannelGroupNumber    ChannelGroupName    ChannelGroupDescription       ChannelName       ChannelDescription    Unit    DataType    NumSamples
    __________________    ________________    _______________________    _________________    __________________    ____    ________    __________

            1                "Trigger"                  ""               "Amplitude sweep"            ""             ""     "Double"       500    
            1                "Trigger"                  ""               "Phase sweep"                ""             ""     "Double"       500

All the TDMS files in the datastore must have the same channel groups and channels. The NumSamples in the channel list is that of the first file in the datastore.

The readall function retrieves all the data from the datastore into MATLAB. Read and plot the data from the first channel group.

data = readall(ds);
stackedplot(data{1})

Amplitude and Phase sweep plot

Read Datastore TDMS Files Individually

You can also analyze data in the datastore one file at a time. Redefine the TDMS datastore with a read size of "file".

ds = tdmsDatastore(folderName, readSize="file");

Iterate through the datastore, reading data from each TDMS file. The read function uses the set read size. For each file, find its maximum and minimum values in the Amplitude sweep channel, and compare it to the cumulative maximum and minimum.

maxAmplitude = 0;
minAmplitude = 0;
while(hasdata(ds))
    data = read(ds);
    maxAmplitude = max(maxAmplitude, max(data{1}.("Amplitude sweep")));
    minAmplitude = min(minAmplitude, min(data{1}.("Amplitude sweep"))); 
end

After the entire dataset is read, view the cumulative maximum and minimum amplitudes.

maxAmplitude
maxAmplitude = 
6.9998

minAmplitude
minAmplitude = 
-6.9982