MATLAB System

Include System object in model

• 

Libraries:
Simulink / User-Defined Functions
HDL Coder / User-Defined Functions

Description

The MATLAB System block brings existing System objects (based on matlab.System) into Simulink^®. It also enables you to use System object APIs to develop new blocks for Simulink. For more information on this block, see Create Custom Blocks Using MATLAB System Block and System objects.

For interpreted execution, the model simulates the block using the MATLAB^® execution engine.

For code generation, the model simulates the block using code generation (using the subset of MATLAB code supported for code generation). The MATLAB System block supports only a subset of the functions available in MATLAB. See Functions and Objects Supported for C/C++ Code Generation for a complete list of functions. These functions include those in common categories, such as:

• Array vs. Matrix Operations, like plus, minus, and power

• Matrix operations, like size and length

• Advanced matrix operations, like lu, inv, svd, and chol

• Trigonometric functions, like sin, cos, sinh, and cosh

By default, the block recognizes 1-D input signals and propagates 1-D output signals as 2-D. Use the supports1DVectorsImpl method to enable the block to recognize and propagate 1-D inputs and outputs as 1-D signals.

Starting in R2025a, the block supports unbounded variable-size signals at its input and output ports. For more information about unbounded variable-size signals, see Unbounded Variable-Size Signals.

System Objects

To use the MATLAB System block, you must first have a new System object™ or use an existing one. For more information, see Author Blocks Using MATLAB System Objects.

Examples

Specify Sample Time for MATLAB System Block System Objects

Control the sample time of the MATLAB System block using System object™ methods.

• Open Script

Implement Block Algorithms Using MATLAB System Object and MATLAB System Block

Use a MATLAB System block to implement an algorithm that generates Pulse Width Modulation (PWM) signal. The PWM signal algorithm is implemented using a MATLAB® System object™. The MATLAB System block integrates the system object into the Simulink® environment. In this example, you can set the duty cycle and frequency interactively to generate different PWM signals.

• Open Model

Ports

Input

In — Signal input to a MATLAB System block

scalar | vector | matrix

The MATLAB System block accepts inputs of the types listed in the Block Characteristics table. For more information, see Data Types Supported by Simulink.

For information on fixed-point support for this block, see Code Acceleration and Code Generation from MATLAB (Fixed-Point Designer).

The MATLAB System block supports Simulink frames. For more information, see Sample- and Frame-Based Concepts (DSP System Toolbox).

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | fixed point

Output

Out — Signal output of a MATLAB System block

scalar | vector | matrix

Signal output of a MATLAB System block that the System object returns.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus

Parameters

System Object Name — Name of the System object

cell array (default)

Specify the full name of the user-defined System object class without the file extension. This entry is case sensitive. The class name must exist on the MATLAB path.

You can specify a System object name in one of these ways:

• Enter the name in the text box.

• Click the list arrow attached to the text box. If valid System objects exist in the current folder, the names appear in the list. Select a System object from this list.

• Browse to a folder that contains a valid System object. If the folder is not on your MATLAB path, the software prompts you to add it.

If you need to create a System object, you can create one from a template by clicking New.

After you save the System object, the name appears in the System object name text box.

Use the full name of the user-defined System object class name. The block does not accept a MATLAB variable that you have assigned to a System object class name.

Programmatic Use

Block Parameter: System

Type: character vector

Value: name of the System object

Default: ' '

New — Create a System object from a template

Basic (default) | Advanced | Simulink Extension

Select one of the options for a System object template.

Basic

Starts MATLAB Editor and displays a template for a simple System object using the fewest System object methods.

Advanced

Starts MATLAB Editor and displays a template for a more advanced System object using most of the System object methods.

Simulink Extension

Starts MATLAB Editor and displays a file that contains utilities for customizing the block for Simulink. This is the same file available in MATLAB when you select New > System Object > Simulink Extension.

After you save the System object, you can enter the name in the System object name text box.

Simulate using — Select the simulation mode

Code generation (default) | Interpreted Execution

Select the simulation mode.

Code generation

On the first model run, simulate and generate code for MATLAB System block using only MATLAB functions supported for code generation. If the structure of the block does not change, subsequent model runs do not regenerate the code.

If the simulation mode is Code generation, System Objects accept a maximum of 32 inputs.

Interpreted execution

Simulate model using all supported MATLAB functions. Choosing this option can slow simulation performance.

Dependency — Dependency parameter for MATLAB System block

auto (default)

After you assign a valid System object class name to the block, the next time you open the block dialog box, the parameter is visible. This parameter appears for every MATLAB System block. You cannot remove it.

• If the block has no tabs, this parameter appears at the bottom of the dialog box.

• If the block has multiple tabs, this parameter appears at the bottom of the first tab of the dialog box.

Saturate on integer overflow — Specify whether overflows saturate

Off (default) | On

On

Overflows saturate to either the minimum or maximum value that the data type can represent. For example, an overflow associated with a signed 8-bit integer can saturate to -128 or 127.

Off

Overflows wrap to the appropriate value that the data type can represent. For example, the number 130 does not fit in a signed 8-bit integer and wraps to -126.

Tips

• Consider selecting this check box when your model has a possible overflow and you want explicit saturation protection in the generated code.

• Consider clearing this check box when you want to optimize efficiency of your generated code. Clearing this check box also helps you to avoid overspecifying how a block handles out-of-range signals. For more information, see Troubleshoot Signal Range Errors.

• When you select this check box, saturation applies to every internal operation on the block, not just the output or result.

• In general, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.

Dependency

This check box appears when you use the showFiSettingsImpl method in the System object.

Programmatic Use

Block Parameter:SaturateOnIntegerOverflow

Type: character vector

Values: 'off' | 'on'

Default: 'off'

Treat these inherited Simulink signal types as fi objects — Specify fi data types

Fixed-point (default) | Fixed-point & Integer

Select which inherited data types to treat fi data types,

Fixed-point

Treat fixed-point data types as fi data types.

Fixed-point & Integer

Treat fixed-point and integer data types as fi data types.

Dependency

This check box appears when you use the showFiSettingsImpl method in the System object.

MATLAB System fimath — Specify fixed-point settings to use

Same as MATLAB (default) | Specify Other

Select which fixed-point math settings to use.

Same as MATLAB

Use the current MATLAB fixed-point math settings.

Specify Other

Enable the edit box for specifying the desired fixed-point math settings. For information on setting fixed-point math, see fimath (Fixed-Point Designer).

Dependency

This check box appears when you use the showFiSettingsImpl method in the System object.

Block Characteristics

Data Types	Booleana | busba | doublea | enumerateda | fixed pointa | halfa | integera | singlea | stringa
Direct Feedthrough	no
Multidimensional Signals	yesa
Variable-Size Signals	yesca
Zero-Crossing Detection	no
a Actual data type or capability support depends on block implementation. b See Nonvirtual Buses and MATLAB System Block for more information. c See Variable-Size Signals for more information.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Actual code generation support depends on block implementation.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

You can define a System object and use it in a MATLAB System block for HDL code generation.

Tunable Parameter Support

HDL Coder supports tunable parameters with the following data types:

• Numeric

• Fixed point

• Character

• Logical

When using tunable parameters with the MATLAB System block, the tunable parameter should be a Simulink.Parameter object with the StorageClass set to ExportedGlobal.

x = Simulink.Parameter 
x.Value = 1 
x.CoderInfo.StorageClass = 'ExportedGlobal' 

For details, see Generate DUT Ports for Tunable Parameters (HDL Coder).

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

If you use a predefined System object, the HDL block properties available are the same as the properties available for the corresponding block.

By default, the following HDL block properties are available.

ConstMultiplierOptimization	Canonical signed digit (CSD) or factored CSD optimization. The default is none. See also ConstMultiplierOptimization (HDL Coder).
ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
DistributedPipelining	Pipeline register distribution, or register retiming. The default is inherit. See also DistributedPipelining (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
LoopOptimization	Unroll, stream, or do not optimize loops. The default is none. See also LoopOptimization (HDL Coder).
MapPersistentVarsToRAM	Map persistent arrays to RAM. The default is off. See also MapPersistentVarsToRAM (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).
ResetType	Suppress reset logic generation. The default is default, which generates reset logic. See also ResetType (HDL Coder).
SharingFactor	Number of functionally equivalent resources to map to a single shared resource. The default is 0. See also Resource Sharing (HDL Coder).
VariablesToPipeline	Warning VariablesToPipeline is not recommended. Use coder.hdl.pipeline (HDL Coder) instead. Insert a pipeline register at the output of the specified MATLAB variable or variables. Specify the list of variables as a character vector, with spaces separating the variables.

Restrictions

• The DUT subsystem must be single-rate.

• Inputs cannot have non-discrete (constant or Inf) sample time.

• To find predefined System objects that are supported for HDL code generation when you use them in the MATLAB System block, see Predefined System Objects Supported for HDL Code Generation (HDL Coder).

• If you use a user-defined System object, it must support HDL code generation. For information about user-defined System objects and requirements for HDL code generation, see HDL Code Generation for System Objects (HDL Coder).

See also Generate Code for User-Defined System Objects (HDL Coder) and HDL Code Generation for System Objects (HDL Coder).

Fixed-Point Conversion

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

Actual data type support depends on block implementation.

Version History

Introduced in R2013b

R2025a: MATLAB System block supports unbounded variable-size signals

MATLAB System block now supports unbounded variable-size signals at the block input and output ports. This enables you to use variable-size signals whose dimensions are unknown during model compilation. For more information about unbounded variable-size signals, see Unbounded Variable-Size Signals.

R2024a: Report runtime errors for MATLAB System blocks in rapid accelerator mode

Report runtime errors for MATLAB System blocks when simulating in rapid accelerator mode by setting the Enable memory integrity checks configuration parameter to Always on.