call MEX-Funcion in a simulink userdefined block

Hi, I have a MEX-function that have several inputs and 2 outputs. In addition I creat a simulink model whit several blocks. I need to call the MEX-Function whit these blocks in the model. how can I do it? It's important for me that arrive to minimum executing and calling time.

Answer 1

[Kaustubha Govind]

MEX-functions can essentially be called just like any other MATLAB function. Please see the available MATLAB Function blocks to find a Simulink block that can be used to execute a MATLAB function.

[omid jab]

thanks dear Kaustubha,I have a MEX-file only. this Mex-file name is "Screen.mexw64", I fond it in psychtoolbox (www.psychtoolbox.org). but I don't have "Screen.c" and "Screen_wrapper.c". I can call it from "MATLAB Fcn" block. but this block is not fast enough. How can I call "Screen.mexw64" as a C-function in "S-Function Builder" for creat a "Level2 matlab s-function"? I use below cod in "s-function builder" block. this cod generate "example.c" and "example_wrapper.c" and "example.mexw64". but when I run my model (tha included genarated MEX-file), MATLAB show me a "matlab system error" window.

*typedef int (__cdecl *MYPROC)(int, mxArray[], int, const mxArray*[]); int nlhs=1; mxArray plhs[2]; int nrhs=1; const mxArray *prhs[2];

    HINSTANCE hinstLib; 
    MYPROC ProcAdd; 
    BOOL fFreeResult, fRunTimeLinkSuccess = FALSE;
    O1 = 1;
     hinstLib = LoadLibrary(TEXT("Screen.mexw64")); 
     if (hinstLib != NULL)
     {
         ProcAdd = (MYPROC) GetProcAddress(hinstLib, "mexFunction");
         if (NULL != ProcAdd) 
         {
             fRunTimeLinkSuccess = TRUE;
//             (ProcAdd) (nlhs, plhs, nrhs, prhs);
             (ProcAdd) ('OpenWindow',0);
         }
         fFreeResult = FreeLibrary(hinstLib);
     }
     if (! fRunTimeLinkSuccess) 
          printf("unable to call the other MEX file\n");*

[Kaustubha Govind]

Omid: Considering that you don't have the actual source code to the MEX-function, I don't see any advantage in calling into the MEX-function via a C S-function - I would wager that the performance will be equivalent to using the MATLAB Function block. Btw, I think the standard way to call MEX-files from C is using mexCallMATLAB. I don't know how LoadLibrary needs to be configured to do this.

[omid jab]

dear Kaustubha,I am an amuteure user and did not know " mexCallMATLAB". this is more suitible and mor simple than my prior method. thanks for introduce it to me. but I have a new problem: my mex-file is called in matlab as [a,b]=Screen('Openwindow',0). I know "nlhs = 2, nrhs = 2, prhs=['OpenWindow',0]". but I dont know, how must write it in C.

[Kaustubha Govind]

Please look at the examples listed at the bottom of the documentation page that I previously linked for mexCallMATLAB.

[omid jab]

I studied all of them, but no understand how can creat a pointer such as prhs=['OpenWindow',0]".

[Kaustubha Govind]

omid: You need to create mxArray's for both - use mxCreateString for the first and mxCreateDoubleScalar for the second.