MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guia do Utilizador descarregar pdf (Página 64)

3 Writing S-Functions As C-MEX files

3-20

The length of the various signals and vectors is configured in the

mdlInitializeSizes routine. The signals as well as their length can be

accessed in S-function routi nes that are called during the simulation loop.

During t he simulation loop, accessing the input signals is performed using:

InputRealPtrs uPtrs = ssGetInputPortRealSignalPtrs(S,portIndex)

This is an array of pointers, where portIndex starts at 0. There is one for each

input port. To access an element of this signal you must use:

*uPtrs[element]

as described by this figure:

Figure 3-5: Accessing Input Data from S-Function Input Ports

Note that input array pointers may point at noncontig uous places in memory.

You can retrieve the output signal by using this code:

real_T *y = ssGetOutputPortSignal(S,outputPortIndex);

S-function

Block

Input 1

Input 2

uPtrs0

...

Block I/O

Vector

InputRealPtrs uPtrs0 = ssGetInputPortRealSignalPtrs(S,0)

To Access Input 1:

uPtrs1

...

InputRealPtrs uPtrs1 = ssGetInputPortRealSignalPtrs(S,1)

To Access Input 2:

1 2 ... 59 60 61 62 63 64 65 66 67 68 69 ... 209 210

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MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guia do Utilizador Página 64