FMU Export with .csv as input

Wanted to check if it will be possible to export as FMU standalone with the input being "From Spreadsheet".

I have tried creating and I was given an error:

"Error:Error encountered in block ResistanceModel_FMU/From Spreadsheet

Caused by:

From Spreadsheet block supports rapid simulation target and the following simulation modes: Normal, Accelerator, and Rapid Accelerator."

Is there an alternative route to doing this, because I plan to have the input for the user to upload their respective file when the FMU is set up.

[Umar]

Hi Sharul Baggio,

The error message you received indicates that the "From Spreadsheet" block is not compatible with the FMU export process in certain configurations. To work around this limitation, consider using a different approach for input handling. One alternative is to utilize a MATLAB function block that reads the spreadsheet data at runtime. This block can be designed to accept user-uploaded files, allowing for dynamic input during simulation.

function data = readSpreadsheet(filePath)

    % Read data from the specified spreadsheet file

    data = readtable(filePath);

end

You can then call this function within your model to load the data dynamically. Hope, this method should help resolve your issue. Please let me know if you have any further questions.

Answer 1

[SBmachine]

Hi @Umar thanks for the suggestion.

I have tried the function you mentioned and was greeted with the following error message.

Error:Function 'readtable' not supported for code generation.

More information

Function 'MATLAB Function' (#91.106.125), line 3, column 12:

"readtable(filePath)"

Launch diagnostic report.

I have tried using readCSV and csvread, and was given the same error as well.

Image below is how I connected the function.

Addition info, I export to FMU with the following steps.

Save>export model to standalone FMU> click fmi 3.0, changed destination folder and click create.

Then the error above was given.

I have also tried swapping the input for speed (v) with a fixed step, to experiment exporting, but was given the

"Code Generation information file does not exist" error.

Thanks in advance for the major help!

[Umar]

Hi @ Sharul Baggio,

That is frustrating. It sounds like these certain MATLAB functions which you tried including readtable, readCSV, and csvread, are not designed to be used in code that is generated for deployment or simulation in environments that do not support these functions. I just went through documentation

https://www.mathworks.com/help/matlab/ref/csvread.html

it mentions that csv not recommended, you have to use read matrix for R2019a and above. Here is documentation for read matrix

https://www.mathworks.com/help/matlab/ref/readmatrix.html

Also, this documentation below shows supported file format for export and import

https://www.mathworks.com/help/matlab/import_export/supported-file-formats-for-import-and-export.html

Also, instead of using unsupported functions for code generation, consider importing data directly through Simulink blocks designed for this purpose. Use blocks like From Spreadsheet or From File that can read data without relying on unsupported MATLAB functions. If you have data stored in CSV format, you can convert it into a format compatible with Simulink, such as using a Constant block to feed in predefined values or using MATLAB Function blocks with compatible coding practices. This is the last alternative to try, Set your model to use a fixed-step solver:

        set_param('your_model_name', 'Solver', 'FixedStepAuto')

 Use the exportToFMU function correctly by specifying necessary parameters:

        exportToFMU('your_model_name', 'FMIVersion', '3.0', 'FMUType', 'CS')

Make sure that any variable inputs or outputs are properly defined and that their data types are compatible with FMI standards.

If you continue to face issues, consider simplifying your model incrementally and testing exports until you isolate the source of errors.

Answer 2

[Rahul]

Hi @Sharul Baggio,

I understand that you are trying to use the "From Spreadsheet" block for your use-case in which the end user will be uploading their spreadsheet file to run the model while the FMU is set up.

As per my understanding the "From Spreadsheet" block does not support generating code that involves building ERT or GRT targets, or using SIL or PIL simulation modes. Hence in this case the FMU is unable to generate code as also mentioned in this MATLAB Answer: https://www.mathworks.com/matlabcentral/answers/2146699-how-can-i-export-roboflow-annotation-to-work-in-matlab?s_tid=srchtitle

A possible workaround could be using "From Workplace" block after saving the spreadsheet content into a workspace variable.

You can refer to the following documentations for reference:

"Save and Load Workspace variables": https://www.mathworks.com/help/matlab/matlab_env/save-load-and-delete-workspace-variables.html

"From Workspace": https://www.mathworks.com/help/simulink/slref/fromworkspace.html

"From Spreadsheet": https://www.mathworks.com/help/releases/R2024a/simulink/slref/fromspreadsheet.html?searchHighlight=from%20spreadsheet&s_tid=doc_srchtitle

"FMU": https://www.mathworks.com/help/simulink/ref_extras/fmu.html

Hope this helps! Thanks.

Answer 3

[Walter Roberson]

You have the fundamental problem that when you deploy to the FMU, the FMU does not have a filesystem to be able to potentially read from a spreadsheet.

The same problem affects most of the potential work-arounds.

Although I do not work in this area myself, I seem to recall that the workaround is to save the data to a .mat file before-hand, and load() the .mat file in the code. If I recall correctly, this will compile the .mat content right into the code. This has the disadvantage that changes to the spreadsheet or .mat file require recompiling.

As best I know, there is no work-around that allows "live" data to be read in on the FMU -- the FMU just doesn't have the right infrastructure to store data.

[AKHIL NANDAN]

@Walter Roberson I have to gracefully disagree to the first point, that FMU does not allow the filesystem to read from spreadsheet. It mostly looks to me as an inability from Mathworks side if it doesn't allow.

FMU's do have a resources folder where you can keep the external binaries and files to be reffered. Dymola allows this resources folder to be generated with the linked external files when you export the FMU, more or less Dymola/Modelica also allows you to read and external file and assigns the parameters during model initialization phase within the FMU itself, meaning no recompilation required.

[Walter Roberson]

Ah, I was getting confused, I thought FMU was one of the various embedded systems, rather than standing for Functional Mock-Up Unit.

Answer 4

[Nils Lande]

This is a very frustrating limitation of the MATLAB FMU export. It is very practical to be able to read parameters and tables from csv-files.

You can do this by writing your own function for reading the csv-file. To do this you have to navigate through a complex maze of MATLAB functions that are not supported for code generation. Both for file operations and for string parsing.

Warning: The AI Chat bots I have tried (Google, Chat GPT, Copilot) are really bad at this. The code they suggest do not pass code generation.

To be able to do this you have to resort to low level file- and string-operations to read the file:

fopen()
fclose()
feof()
fgetl()
strtok()
strip()
line()

For parsing you must avoid these:

textscan()
strsplit()
split()
strings()
regexprep()

A very crude example:

fileID = fopen(filePath);
while(~feof(fileID))
    line = fgetl(fileID);
    tokens = cell(1,0);
    remain = str;
    while (remain ~= "")
        [token,remain] = strtok(remain, separator);
        tokens{end+1} = token;
    end
    % Process the values in token
end    
fclose(fileID);