MATLAB: Call M-script in C/C++ Sfunction

s-functionsimulink

I have a S-Function written in C. I want to call a m-script during from this S-Function. How is this possible?

Thanke

Best Answer

I understand that you have written a S-Function in C and you want to call a matlab script from that function. I assume that you are using MATLAB R2016b.

You can do the above by using 'mexEvalString('Name_of_Script')' function in mdlOutputs method of S-Function. To illustrate, I am using timestwo example available at the following link http://in.mathworks.com/help/simulink/sfg/example-of-a-basic-c-mex-s-function.html and a dummy script plotline.m which plots a line. I am calling this MATLAB Script from timestwo S-function.

plotLine.m looks as below:

x = [1 2 3];
y = [1 2 3];
plot(x,y);

mdlOutputs method in timestwo.c looks as below:

static void mdlOutputs(SimStruct *S, int_T tid)
{
  int_T i;
  InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0);
  real_T *y = ssGetOutputPortRealSignal(S,0);
  int_T width = ssGetOutputPortWidth(S,0);
    for (i=0; i<width; i++) {
        *y++ = 2.0 *(*uPtrs[i]);
    }
    mexEvalString("plotLine");
 }

Now use mex timestwo.c to compile this S-Function. Run the S-function and notice that it also executes the script now.

I hope that this helps.

Related Solutions

MATLAB: How to allocate and free memory for a PWork vector in a C-MEX S-function

First, the S-Function needs to specify how many PWork vectors it needs (using ssSetNumPWork) either in mdlInitializeSizes or in mdlSetWorkWidths. Simulink calls the above functions in the S-Function at the beginning of the model initialization stage (internally we refer to this part of the initialization stage as the compile phase). Towards the end of model initialization stage (internally we refer to this part of the initialization stage as the link phase), Simulink allocates the specified number of PWorks. Upon completing the model initialization stage, Simulink calls the S-Function's mdlStart. In the mdlStart function, the S-Function can allocate memory and store a pointer to it in the PWork array. The following code snippet illustrates specifying, allocating, using, and freeing memory using PWorks.

mdlInitializeSizes(SimStruct* S) 
{ 
/* snip */
ssSetNumPWork(S, 1);
/* snip */ 
}
mdlStart(SimStruct* S) 
{ 
/* snip */
void* ptr = malloc(1024 /* number of bytes */); 
if (ptr == NULL) { 
/* report memory allocation error */ 
ssSetErrorStatus(S, "Memory allocation error"); 
return; 
} 
ssSetPWorkValue(S, 0, ptr);
/* snip */ 
}
mdlOutputs(SimStruct* S, int_T tid) 
{ 
void* ptr = ssGetPWorkValue(S, 0);
/* snip */ 
}
mdlTerminate(SimStruct* S) 
{ 
/* snip */
/* free the memory allocated in mdlStart */ 
if (ssGetPWork(S) != NULL) { 
void* ptr = ssGetPWorkVale(S,0); 
if (ptr != NULL) free(ptr); 
}
/* snip */ 
}

For a more complete example on using PWork vectors please look at the following example in the documentation.

http://www.mathworks.com/help/releases/R2009b/toolbox/simulink/sfg/bre1pj2.html#bre1ps0

MATLAB: Is there an example of dynamically sized input ports with different widths in a C-MEX S-function

Here is an example showing how to write a C-MEX S-function with dynamically sized input ports that accepts 1-D (vector) signals with different widths in Simulink 6.2 (R14SP2).

In Level 2 S-functions you need to use the two new methods: mdlSetInputPortWidth and mdlSetOutputPortWidth. This is described in the S-function section of the Using Simulink User's Guide.

If you open up the attached S-function source file, you will notice the following lines after mdlInitializeSizes:

#if defined(MATLAB_MEX_FILE)
# define MDL_SET_INPUT_PORT_WIDTH
    static void mdlSetInputPortWidth(SimStruct *S, int_T port,
                                      int_T inputPortWidth)
    {
        ssSetInputPortWidth(S,port,inputPortWidth);
    }
# define MDL_SET_OUTPUT_PORT_WIDTH
    static void mdlSetOutputPortWidth(SimStruct *S, int_T port,int_T outputPortWidth)
    {
        ssSetOutputPortWidth(S,port,outputPortWidth);
    }
#endif

These methods are called with the candidate widths for dynamically sized ports. If the proposed widths are acceptable, the methods proceed to set the actual ports widths using ssSetInputPortWidth and ssSetOutputPortWidth.

Best Answer

Related Solutions

MATLAB: How to allocate and free memory for a PWork vector in a C-MEX S-function

MATLAB: Is there an example of dynamically sized input ports with different widths in a C-MEX S-function

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