MATLAB: How to import DIAdem measurement data into MATLAB

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I have TDM files which contain measurements taken with National Instruments DIAdem software. I would like to import the data into MATLAB to visualize and post-process the data.

Best Answer

The ability to directly import DIAdem TDMATLAB files is not available in MATLAB.

To work around this issue, you can use the "loadlibrary" function as demonstrated in the following example from National Instruments™:

Reading TDM/TDMS Files with MathWorks, Inc. MATLAB® Software

http://www.ni.com/example/30957/en/

You can also export the measurement data from DIAdem into MS Excel or as an ASCII-formatted text file, and then import the data into MATLAB. Note that MS Excel is limited to 2^16 (65,536) rows for older versions and 2^20 (1,048,576) rows for newer versions.

To import Excel data into MATLAB you can use the "xlsread" command. The best function to use depends on the format of the text file. Several possible options are "csvread", "dlmread" or "textscan".

For more information on each of these commands please execute one of the commands below at the MATLAB command prompt:

doc xlsread
doc csvread
doc dlmread
doc textscan

Related Solutions

MATLAB: How to specify a datetime format when reading a .csv/Excel file

You can use 'setvaropts' to change the format of datetime variables. For example:

opts = detectImportOptions('example.csv');
opts = opts.setvaropts('myVariable','InputFormat','M/d/yyyy','DateTimeFormat','dd-MMM-yyyy');
t = readtable('example.csv',opts)
% 'example.csv' contains the column:
% myVariable
% 1/31/2020

'InputFormat' tells 'readtable' how to interpret the values in the file, while 'DateTimeFormat' tells MATLAB how to display the datetimes once they are in MATLAB.

For more information, refer to the "Import Date and Time Data" section on the following documentation page:

https://www.mathworks.com/help/matlab/ref/matlab.io.text.delimitedtextimportoptions.setvaropts.html

MATLAB: How to read TDMS data that is streamed through a UDP socket using MATLAB 7.9 (R2009a)

The ability to interpret National Instruments TDM/TDMS data is not available in MATLAB. To work around this issue, refer to the following link:

Reading TDM/TDMS Files with MathWorks, Inc. MATLAB® Software

https://forums.ni.com/t5/Example-Code/Reading-TDM-TDMS-Files-with-The-MathWorks-Inc-MATLAB-Software/ta-p/3996480?profile.language=en

The DIAdem Connectivity Library provided by National Instruments is tailored to read from TDM/TDMS files only. However, you can read the TDMS binary data being sourced from a UDP socket (or received via TCP/IP) using the DIAdem library in a two step process:

1. Write the TDMS data to a binary file:

a. Create an empty data file with the TDM or TDMS extension using the FOPEN command.

b. Read the data from the UDP socket using the FREAD or FSCANF command as appropriate and write the data to the file created using the FWRITE or FPRINTF command.

c. Continue writing to this file until all the bytes have been received over the UDP socket.

2. Provide the above saved file as an input to the "Read_TDMData.m" example file provided along with the DIAdem library.

Best Answer

Related Solutions

MATLAB: How to specify a datetime format when reading a .csv/Excel file

MATLAB: How to read TDMS data that is streamed through a UDP socket using MATLAB 7.9 (R2009a)

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