Get the number of elements in a bus signal


int_T ssGetNumBusElements(SimStruct *S, int_T busTypeID)



SimStruct that represents an S-Function block


The bus data type identifier that represents the bus signal




Use to determine the number of elements in the bus. If one of the elements is also a bus signal, use ssGetNumBusElements recursively to determine the number of elements in the sub-bus signal. The second argument is the identifier that Simulink® returns after you register the bus object that represents the bus signal. (To register a bus object, use ssRegisterTypeFromParameter or an equivalent method.)

Bus S-function Usage Guidelines

Use this S-function in simulations. You cannot use this S-function for code generation.

This S-function does not support bus elements that have any of the following characteristics:

  • Variable dimensions

  • Frames

  • Enumerated (enum) data types

To use this S-function and other bus-related S-functions, before you run the simulation, execute the following MATLAB® command:

set_param(block_handle, 'EnableBusSupport', 'on')

To automate setting the EnableBusSupport parameter, use one of the following approaches:

  • Add the command to the model initialization callback.

  • Mask the S-Function block and add the command to the mask initialization callback


C, C++


static void mdlOutputs(SimStruct *S, int_T tid)
    DTypeId    dType    = ssGetOutputPortDataType(S, 0);
    const void *u       = ssGetInputPortSignal(S, 0);
    int        numElems = ssGetNumBusElements(S, dType);
    int        i;
    for(i=0; i<numElems; i++) {

Was this topic helpful?