Real-Time Workshop User's Guide

Introduction

Using the S-function target, you can build an S-function component and use it as an S-Function block in another model. The S-function code format used by the S-function target generates code that conforms to the Simulink C MEX S-function application programming interface (API). Applications of this format include:

• Conversion of a model to a component. You can generate an S-Function block for a model, m1. Then, you can place the generated S-Function block in another model, m2. Regenerating code for m2 does not require regenerating code for m1.
• Conversion of a subsystem to a component. By extracting a subsystem to a separate model, and generating an S-Function block from that model, you can create a reusable component from the subsystem. See Creating an S-Function Block from a Subsystem for an example of this procedure.
• Speeding up simulation. In many cases, an S-function generated from a model performs more efficiently than the original model.
• Code reuse. You can incorporate multiple instances of one model inside another without replicating the code for each instance. Each instance will continue to maintain its own unique data.

The S-function target generates noninlined S-functions. You can generate an executable from a model that contains generated S-functions by using the generic real-time or real-time malloc targets. You cannot use the Real-Time Workshop Embedded Coder target for this purpose, since it requires inlined S-functions.

You can place a generated S-Function block into another model from which you can generate another S-function format. This allows any level of nested S-functions.

Note that sample times propagation for the S-function code format is slightly different from the other code formats. A generated S-Function block will inherit its sample time from the model in which it is placed if no blocks in the original model specify their sample times.

The S-Function Target

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