Why do I receive an "Error while obtaining sizes from MEX S-function. The specified module could not be found." error message?

I am running a model with an S-Function built from blocks from the Signal Processing Blockset. The machine that I am running on does not have the Signal Proessing Blockset installed. I assumed once the S-Function is built the original library should not be needed.

However, I get the following error for my S-Function:

Error while obtaining sizes from MEX S-function 'TEST12_sf' in 'TEST12SF/RTW S-Function'.
MATLAB error message:
Invalid MEX-file 'C:\TEST12\TEST12_sf.mexw32': The specified module could not be found.

Why is this happening?

Answer 1

[MathWorks Support Team]

This error typically occurs if the MEX-file references a runtime library, but Simulink cannot find the associated DLL file. Here are the steps to resolve this issue:

 

1. Move the DLL File

Place the missing DLL file to the same directory as the model or ensure it is on the Windows system path.

 

Specific scenario - DSP Library

For this scenario using the Signal Processing Blockset, copy the DSP shared library file "dsp_rt.dll" from $MATLABROOT/bin/win32 to the same directory on the target machine.

 

2. Identify the missing DLL

This error message does not specify which DLL file is missing. If it is not immediately obvious which other DLL files the MEX function needs, check the header files the S-function includes in its "#include" declarations.

 

If it is still unclear, load the MEX file in the dependency walker and look for libraries marked with a question mark in a yellow circle.

Dependency Walker can be downloaded from:

www.dependencywalker.com

3. Rebuild the S-Function

Alternatively, you can rebuild the S-Function with a different Make command. To do this, navigate to "Simulation > Configuration Parameters > Real-Time Workshop", and set the "Make command" parameter to:

make_rtw OPT_OPTS="$(DEFAULT_OPT_OPTS) -DREBUILD_LIBRARIES"