MATLAB: S-function input ports with different variable dimensions

inputs-functionsimulink

Hi all,

I am writing a C S-function for Simulink, with two input ports. The width of both ports is set to DYNAMICALLY_SIZED, because the input is a one dimensional vector with 1 or 4 elements. Everything goes well as long as both input signals have the same dimension (1 or 4). However, when the input signals have different dimensions (1 for the first and 4 for the second, or vice versa) the S-function doesn't run. There is an error which says that the input port is vector with 1 element, allthough the signal that goes to the input port is a vector with 4 elements.

Does anyone have an idea on what I am doing wrong, or what might be the solution to this problem?

Best Answer

The documentation suggests that you implement mdlSetInputPortDimensionInfo. Please try adding these lines to your S-function:

#define MDL_SET_INPUT_PORT_DIMENSION_INFO
#if defined(MDL_SET_INPUT_PORT_DIMENSION_INFO) && defined(MATLAB_MEX_FILE)
void mdlSetInputPortDimensionInfo(SimStruct *S, int_T port,
  const DimsInfo_T *dimsInfo)
{
    if (!ssSetInputPortDimensionInfo(S, port, dimsInfo)) return;
}
#endif

Related Solutions

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.

MATLAB: Is there a different syntax in the documentation for the S-function callback method mdlSetDefaultPortDimensionInfo in Simulink 6.0 (R14) and the example listed in the reference sfun_matadd.c

This is an error within the documentation for Simulink within the S-function callback method mdlSetDefaultPortDimensionInfo. The documentation should read as follows:

Syntax

void mdlSetDefaultPortDimensionInfo(SimStruct *S)

Best Answer

Related Solutions

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

MATLAB: Is there a different syntax in the documentation for the S-function callback method mdlSetDefa​ultPortDim​ensionInfo in Simulink 6.0 (R14) and the example listed in the reference sfun_matadd.c

Related Question

MATLAB: Is there a different syntax in the documentation for the S-function callback method mdlSetDefaultPortDimensionInfo in Simulink 6.0 (R14) and the example listed in the reference sfun_matadd.c