S-Fuction Steam mixer design: How to use m-function in a C code

Asked by Maliha on 24 Oct 2014

Latest activity Commented on by Maliha on 2 Nov 2014

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Hi, for my project I have to design this mixer in S-function, and the primary code is below. Problem is for this I need to use the XSteam.m function to get the enthalpy. How do I do that? Any kind of help would be appreciated. Also let me know if i can improve the code in any way

#define S_FUNCTION_NAME MMM #define S_FUNCTION_LEVEL 2

/* * Need to include simstruc.h for the definition of the SimStruct and * its associated macro definitions. */ #include "simstruc.h" #include stdio.h #include math.h

/*====================* * S-function methods ====================*/

static void mdlInitializeSizes(SimStruct *S) {

    ssSetNumSFcnParams(S, 1);  /* Number of expected parameters */
    if (ssGetNumSFcnParams(S) != ssGetSFcnParamsCount(S)) {
        /* Return if number of expected != number of actual parameters */
        return;
    }
    ssSetNumContStates(S, 0);
    ssSetNumDiscStates(S, 0);
    if (!ssSetNumInputPorts(S, 5)) return;
    ssSetInputPortWidth(S, 0, 1);
    ssSetInputPortRequiredContiguous(S, 0, true); /*direct input signal access*/
    ssSetInputPortDirectFeedThrough(S, 0, 1);
    if (!ssSetNumOutputPorts(S, 2)) return;
    ssSetOutputPortWidth(S, 0, 1);
    ssSetNumSampleTimes(S, 1);
    ssSetNumRWork(S, 0);
    ssSetNumIWork(S, 0);
    ssSetNumPWork(S, 0);
    ssSetNumModes(S, 0);
    ssSetNumNonsampledZCs(S, 0);
    /* Specify the sim state compliance to be same as a built-in block */
    ssSetSimStateCompliance(S, USE_DEFAULT_SIM_STATE);
    ssSetOptions(S, 0);
}

static void mdlInitializeSampleTimes(SimStruct *S) { ssSetSampleTime(S, 0, CONTINUOUS_SAMPLE_TIME); ssSetOffsetTime(S, 0, 0.0);

}

#define MDL_INITIALIZE_CONDITIONS /* Change to #undef to remove function */ #if defined(MDL_INITIALIZE_CONDITIONS)

static void mdlInitializeConditions(SimStruct *S)
{
}
#endif /* MDL_INITIALIZE_CONDITIONS */

#define MDL_START /* Change to #undef to remove function */ #if defined(MDL_START)

static void mdlStart(SimStruct *S)
{
}
#endif /*  MDL_START */

static void mdlOutputs(SimStruct S, int_T tid) { double *Mpgin = ( double)ssGetInputPortRealSignal(S,0); double Tpgin = ( double)ssGetInputPortSignal(S,1); double Mis = (double)ssGetInputPortSignal(S,2); double Tis = (double)ssGetInputPortSignal(S,3); double Ppg = ( double)ssGetInputPortSignal(S,4); double *Mpgout = ssGetOutputPortSignal(S,0); double *Tpgout = ssGetOutputPortSignal(S,1);

    double Hpgin, Qpgin, His, Qis, Qpgout, Hpgout;
    Mpgout[0] = Mpgin[0]+  Mis[0];
 Hpgin = XSteam('h_pt',Ppg[0],Tpgin[0]);
 Qpgin = Hpgin*Mpgin[0];
 His = XSteam('h_pt',Ppg[0],Tis[0]);
 Qis = His*Mis[0];
 Qpgout = Qis + Qpgin;
 Hpgout = Qpgout/Mpgout[0];
*Tpgout = XSteam('t_ph',Ppg[0],Hpgout) ;

}

#define MDL_UPDATE /* Change to #undef to remove function */ #if defined(MDL_UPDATE)

static void mdlUpdate(SimStruct *S, int_T tid)
{
}
#endif /* MDL_UPDATE */

#define MDL_DERIVATIVES /* Change to #undef to remove function */ #if defined(MDL_DERIVATIVES)

static void mdlDerivatives(SimStruct *S)
{
}
#endif /* MDL_DERIVATIVES */
 */
static void mdlTerminate(SimStruct *S)
{
}

/*======================================================* * See sfuntmpl_doc.c for the optional S-function methods ======================================================*/

/*=============================* * Required S-function trailer =============================*/

#ifdef MATLAB_MEX_FILE /* Is this file being compiled as a MEX-file? / #include "simulink.c" / MEX-file interface mechanism / #else #include "cg_sfun.h" / Code generation registration function */ #endif

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Answer by Kaustubha Govind on 2 Nov 2014

Accepted Answer

Please see these previously answered questions on this topic:

http://www.mathworks.com/matlabcentral/answers/85499-plot-x-axis-and-y-axis-with-mexcallmatlab

http://www.mathworks.com/matlabcentral/answers/158737-is-there-any-possibility-of-s-function-written-in-c-language-calling-matlab-function-library-and-i

1 Comment

Maliha on 2 Nov 2014

thanks, I solved the problem on my own. Now I am having issues with another code. Help will be appreciated :)

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