MATLAB: Am I unable to use the PRINTF function from the standard C libraries inside the wrapper code of the C-MEX S-function

4.1r12.1s-functionsimulink

If I use the PRINTF function in my C-MEX S-function it works fine. But if I use this in some wrapper code that is called from my S-function, this function does not work. I have "#included" the standard "stdio.h" library but still have this problem.

Best Answer

You cannot use PRINTF in wrapper function code. Try using "ssPrintf" which is defined in the simstruc.h file. This will expand to 'mexPrintf' for simulation and 'printf' for real-time code. See "Writing S-functions Guide" page 10-118 for details on this macro.

You should also #include the simstruc.h file in your wrapper code when using "ssPrintf".

Related Solutions

MATLAB: How to use “mexPrintf” for simulation and “printf” for code generation in a MATLAB Function Block using coder.ceval

You can use the "MATLAB_MEX_FILE" C preprocessor macro in your custom C code to determine whether you are compiling for a MEX target. For example, you can use this macro to define a custom "printOutput" function:

#include <stdio.h>
#include <stdlib.h>
#ifdef MATLAB_MEX_FILE
#include "mex.h"
#endif
void printOutput(const char* str);
#ifdef MATLAB_MEX_FILE
// Use the mexPrintf function
void printOutput(const char* str) {
    mexPrintf(str);
}
#else
// Use the standard C printf function
void printOutput(const char* str) {
    printf(str);
}
#endif

This function is defined to call "mexPrintf" when compiled for a MEX and "printf" otherwise.

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

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.

Best Answer

Related Solutions

MATLAB: How to use “mexPrintf” for simulation and “printf” for code generation in a MATLAB Function Block using coder.ceval

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

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