Access to defaultParam struct

Using the Matlab/Simulink Coder functionality, coming from an older version of Matlab (2015) where access to the model Parameters could be realized through a C++ data structure, I ran into trouble when trying to disclose this data under Matlab2023. Previously the RTW/Coder generated code that gave access to the parameter struct with a function like:

# define rtmGetDefaultParam(rtm) ((rtm)->ModelData.defaultParam)

It looks like this function was generated as parameters were declared with StorageClass = SimulinkGlobal. Changing the setting to “Model default”, did not bring the access to the defaultParam struct. I am looking at the alternative setting so that the model parameters are still present under a struct that can be accessed through a function similar to the above. Can someone give me some guidance on this?

Answer 1

[Hassaan]

To regain access to model parameters in a structured way in MATLAB R2023 using MATLAB/Simulink Coder, you may need to adjust the code generation settings and possibly use new functionality to achieve a similar outcome as was available in MATLAB R2015. Here's a some of steps you could take:

1. Review Code Generation Settings: Check "Code Generation" settings in the Model Configuration Parameters for parameter data and tunable parameters. Make sure they are configured to match your desired output.
2. Use Simulink Data Dictionary: Manage parameters and signals through a Simulink Data Dictionary for more accessible data control.
3. Define Custom Storage Classes: Create a custom storage class in the Simulink Coder Dictionary to store parameter data in a global structure.
4. Check for Deprecated Features: Use the provided MATLAB command to review deprecated features and update your model accordingly.
5. Employ Post-Code-Generation Command: Use the PostCodeGenCommand to manipulate the generated code to include functions or structures for accessing parameters.
6. Seek Help from MATLAB Answers or MathWorks Support: For specific guidance on changes in code generation from older to newer MATLAB versions.
7. Examine Generated Code: Look into the generated code for the current method of parameter storage and modify if necessary.
8. Use Legacy Code Tool: Integrate old code with new models if certain functionalities are no longer supported directly.
9. Consider Backward Compatibility: Make sure your model updates consider any backward compatibility issues.

Here's an example of how you might define a custom storage class to generate a global structure for parameters:

% Define a package for custom storage classes
pkg = Simulink.data.createCustomStorageClassPackage('MyPackage', ...
    'Description', 'A package of custom storage classes');

% Define a custom storage class
csc = Simulink.data.createClass(pkg, 'MyStorageClass', ...
    'Description', 'A custom storage class for parameters', ...
    'DataScope', 'Exported', ...
    'HeaderFile', 'myParameters.h', ...
    'GetFunction', 'myModel_GetParameters');

----------------------------------------------------------------------------------------------------------------------------------------------------------------------

If you find the solution helpful and it resolves your issue, it would be greatly appreciated if you could accept the answer. Also, leaving an upvote and a comment are also wonderful ways to provide feedback.

Professional Interests

• Technical Services and Consulting
• Embedded Systems | Firmware Developement | Simulations
• Electrical and Electronics Engineering

Feel free to contact me.

[Ton van der Post]

Thanks Muhammad for the guidance.

After setting it up properly, it appeared that I overlooked one line in the generated code:

extern P_MyModel_T MyModel_P;

This exported the struct with parameters and solved my problem.