S-Functions Simulik

®

Model-Based and System-Based Design

Writing S-Functions
Version 5

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Printing History: October 1998 First printing Revised for Simulink 3.0 (Release 11) November 2000 Second printingRevised for Simulink 4.0 (Release 12) June 2001 Online only Revised for Simulink 4.1 (Release 12.1) July 2002 Third printing Revised for Simulink 5.0 (Release 13) September 2003Online only Revised for Simulink 5.1 (Release 13SP1) October 2004 Online only Revised for Simulink 5.2 (Release 13SP2)

Contents
Overview of S-Functions

1
What Is an S-Function? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Using S-Functions in Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Passing Parameters to S-Functions . . . . . . . . . . . . .. . . . . . . . . 1-4 When to Use an S-Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 How S-Functions Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mathematics of Simulink Blocks . . . . . . . . . . . . . . . . . . . . . . . . Simulation Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S-Function Callback Methods . . . . .. . . . . . . . . . . . . . . . . . . . . .
1-6 1-6 1-6 1-9

Implementing S-Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 M-File S-Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 MEX-File S-Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11 S-Function Concepts . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . Direct Feedthrough . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dynamically Sized Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Setting Sample Times and Offsets . . . . . . . . . . . . . . . . . . . . . .
1-13 1-13 1-13 1-15

S-Function Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-18

Writing M...