How do I make an S-Function run-time parameter instance-specific inside a model reference?

I have an S-Function with run-time parameters defined using the workflow here: https://www.mathworks.com/help/simulink/sfg/run-time-parameters-cpp.html

How can I promote that run-time parameter to be a Model Argument?

Answer 1

[MathWorks Support Team]

You first need to set the "transformed" field of the ssParamRec struct to RTPARAM_MAKE_TRANSFORMED_TUNABLE. Then you can create a Model Workspace parameter marked as argument, and you use that parameter in place of the dialog parameter that is bound to your runtime parameter:

This makes the connection between the instance-specific parameter in the Model Workspace, and the run-time parameter you defined in your S-Function.

A working example is attached. The S-Function is in scalar_param_sfun.c and it uses a dialog parameter and defines a run-time parameter derived from that dialog parameter. In the S-Function code you will see a run-time parameter definition like this:

    /* Configure run-time parameter information */
    p.name             = "myParam";
    p.nDimensions      = 2;
    p.dimensions       = myParamDims;
    p.dataTypeId       = RUN_TIME_DATA_TYPE;
    p.complexSignal    = COMPLEX_NO;
    p.data             = myParam;
    p.dataAttributes   = NULL;
    p.nDlgParamIndices = 1; //only derive from the first dialog parameter
    p.dlgParamIndices  = &dlg;
    p.transformed      = RTPARAM_MAKE_TRANSFORMED_TUNABLE;  //This is required to tune the parameter inside a model reference
    p.outputAsMatrix   = false;

For more information, see:

https://www.mathworks.com/help/simulink/sfg/run-time-parameters-cpp.html

https://www.mathworks.com/help/simulink/sfg/sssetruntimeparaminfo.html

https://www.mathworks.com/help/rtw/ug/specify-instance-specific-parameter-values-for-reusable-referenced-models.html