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S-Function

Include S-function in model

Libraries:
Simulink / User-Defined Functions

Description

The S-Function block provides access to S-functions from a block diagram. The S-function named as the S-function name parameter can be a Level-1 or Level-2 C MEX S-function (see MATLAB S-Function Basics for information on how to create S-functions).

Note

Use the Level-2 MATLAB S-Function block to include a Level-2 MATLAB^® S-function in a block diagram.

The S-Function block displays the name of the specified S-function and the number of input and output ports specified by the S-function. Signals connected to the inputs must have the dimensions specified by the S-function for the inputs.

Examples

Inverted Pendulum with Animation

Use a Simulink® to model and animate an inverted pendulum system. An inverted pendulum has its center of mass above its pivot point. To stably maintain this position, the system implements control logic to move the pivot point below the center-of mass as the pendulum starts to fall. The inverted pendulum is a classic dynamics problem used to test control strategies.

Open Model

Custom Code and Hand Coded Blocks Using the S-function API

This library launches examples of different types of Simulink® S-functions. Simulink S-functions allow you to extend Simulink with new hand coded blocks, interface to custom external code, and create live interfaces to other programs. Use this example to access models containing S-functions in the C, C++, M, and Fortran.

Open Script

Run Quality Checks on S-Functions

Use S-Function analyzer programmatic interfaces to check S-functions for potential problems and improvements.

Open Model

Ports

Input

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In — Signal input to an S-function block
scalar | vector | matrix

You can configure input port using the mdlInitializeSizes callback function. Use the mdlInitializeSizes function to specify number of input ports, dimension of input signals, sample time of each port, and if ports are direct feedthrough.

Output

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Out — Signal output of an S-function block
scalar | vector | matrix

You can configure output port using the mdlInitializeSizes callback function. Use the mdlInitializeSizes function to specify number of output ports, dimension of output signals, and sample time of each port.

Parameters

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S-function name — Name of the S-function
character array (default)

Use this parameter to specify the name of your S-function.

Programmatic Use

Block Parameter: FunctionName

Type: character vector

Value: name of the S-function

Default: 'system'

S-function parameters — Additional S-function parameters
cell array (default)

Specify the additional S-function parameters.

The function parameters can be specified as MATLAB expressions or as variables separated by commas. For example,

A, B, C, D, [eye(2,2);zeros(2,2)]

Note that although individual parameters can be enclosed in brackets, the list of parameters must not be enclosed in brackets.

Programmatic Use

Block Parameter: Parameters

Type: character vector

Value: S-function parameters

Default: ' '

S-function modules — List additional files for code generation
cell array (default)

This parameter applies only if this block represents a C MEX S-function and you intend to use the Simulink^® Coder™ software to generate code from the model containing the block. If you use it, when you are ready to generate code, you must force the coder to rebuild the top model as explained in Control Regeneration of Top Model Code (Simulink Coder).

For more information on using this parameter, see Specify Additional Source Files for an S-Function (Simulink Coder).

Programmatic Use

Block Parameter: SFunctionModules

Type: character vector

Value: character vector of file names

Default: ' '

Block Characteristics

Data Types	`Boolean^a` \| `bus^a` \| `double^a` \| `fixed point^b^a` \| `half^a` \| `integer^a` \| `single^a` \| `string^a`
Direct Feedthrough	`yes^a`
Multidimensional Signals	`yes^a`
Variable-Size Signals	`yes^a`
Zero-Crossing Detection	`yes^a`
^a Actual data type or capability support depends on block implementation. ^b See Writing Fixed-Point S-Functions for details on using fixed-point data types in S-functions.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Actual code generation support depends on block implementation.
S-functions that call into MATLAB are not supported for code generation.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Actual data type support depends on block implementation.
See Integrate External Code (Fixed-Point Designer) for details on using fixed-point data types in S-functions.

Version History

Introduced before R2006a

S-Function

Description