Create System Objects

Write a MATLAB^® class that creates and defines a new System object™

You can define your own System object by customizing the implementation methods. Use graphical tools to explore the comprehensive API for creating System objects. For example, you can insert methods to initialize, run, reset, and terminate System objects. For an introduction to defining a System object, see Define Basic System Objects.

Methods

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Authoring Methods (Protected)

Input Specification

`getNumInputsImpl`	Number of inputs to the System object
`isInputDataTypeMutableImpl`	Set whether System object input data type can change
`isInputSizeMutableImpl`	Set whether System object input size can change
`isInputComplexityMutableImpl`	Set whether System object input complexity can change
`isInputDirectFeedthroughImpl`	Direct feedthrough status of input
`getInputDimensionConstraintImpl`	Define input dimension constraints for dataflow subsystems

Output Specification

`getNumOutputsImpl`	Number of outputs from System object
`getOutputDataTypeImpl`	Data types of output ports
`getOutputSizeImpl`	Sizes of output ports
`isOutputComplexImpl`	Complexity of output ports
`isOutputFixedSizeImpl`	Fixed- or variable-size output ports
`getOutputDimensionConstraintImpl`	Define output dimension constraints for dataflow subsystems

State Specification

`getDiscreteStateSpecificationImpl`	Discrete state size, data type, and complexity
`isDiscreteStateSpecificationMutableImpl`	Control whether discrete states can change data type
`getDiscreteStateImpl`	Discrete state property values

Sample Time Specification

`getSampleTimeImpl`	Specify sample time type, offset time, and sample time
`allowModelReferenceDiscreteSampleTimeInheritanceImpl`	Model reference sample time inheritance status for discrete sample times

Interface Specification

`getGlobalNamesImpl`	Global variable names for MATLAB System block
`getInterfaceImpl` (Simulink)	Set System object as message or data
`isTunablePropertyDataTypeMutableImpl`	Set whether tunable properties can change data type
`isDoneImpl`	End-of-data flag
`getSimulateUsingImpl`	Specify value for Simulate using parameter
`getSimulinkFunctionNamesImpl`	Register Simulink function names used in your System object
`showFiSettingsImpl`	Fixed point data type tab visibility for System objects
`supportsMultipleInstanceImpl`	Support System object in Simulink For Each subsystem
`getImpulseResponseLengthImpl`	Define length of input effects for dataflow subsystems
`supports1DVectorsImpl`	Enable MATLAB System block to use 1-D signals for input and output

Block Dialog and Appearance

`getPropertyGroupsImpl`	Property groups for System object display
`showSimulateUsingImpl`	Visibility of Simulate using parameter
`getIconImpl`	Name to display as block icon
`getHeaderImpl`	Header for System object display
`getInputNamesImpl`	Names of MATLAB System block input ports
`getOutputNamesImpl`	Names of MATLAB System block output ports
`isInactivePropertyImpl`	Status of inactive property

Simulation Methods

`setupImpl`	Initialize System object
`stepImpl`	System output and state update equations
`resetImpl`	Reset System object states
`releaseImpl`	Release resources
`processTunedPropertiesImpl`	Action when tunable properties change
`validatePropertiesImpl`	Validate property values of System object
`processInputSpecificationChangeImpl`	Perform actions when input size, complexity, or data type change
`validateInputsImpl`	Validate inputs to System object
`updateImpl`	Update object states based on inputs

Clone, Save, and Load

`loadObjectImpl`	Load System object from MAT file
`saveObjectImpl`	Save System object in MAT file
`cloneImpl`	Create duplicate System object

Help

infoImpl Information about System object

Query Functions (Protected)

Functions for Implementing Authoring Methods

`setProperties`	Set property values using name-value pairs when creating System object
`propagatedInputComplexity`	Complexity of input during Simulink propagation
`propagatedInputDataType`	Data type of input during Simulink propagation
`propagatedInputFixedSize`	Fixed-size status of input during Simulink propagation
`propagatedInputSize`	Size of input during Simulink propagation
`createSampleTime`	Create sample time specification object
`getSampleTime`	Query sample time
`getCurrentTime`	Current simulation time in MATLAB System block
`setNumTicksUntilNextHit` (Simulink)	Set the number of ticks in Simulink sample time
`displayScalarObject`	Display format for scalar objects
`getHeader`	Build customized display header text
`getFooter`	Build customized display footer text

Implementation Methods (Public)

Methods for Implementing System Objects

`nargin`	Number of input arguments for System object
`nargout`	Number of output arguments for System object
`getNumInputs`	Number of inputs required to call the System object
`getNumOutputs`	Number of outputs from calling the System object
`setup`	One-time set up tasks for System objects
`reset`	Reset internal states of System object
`step`	Run System object algorithm
`release`	Release resources and allow changes to System object property values and input characteristics
`clone`	Create duplicate System object
`isDone`	End-of-data status
`isLocked`	Determine if System object is in use
`delete`	Delete System object
`output`	Query current output of a System object
`update`	Update state of a System object based on inputs
`supportsMultipleInstance`	Check support for Simulink For Each subsystem for System object
`getDiscreteState`	Get the discrete states of a System object
`getDiscreteStateSpecification`	Get the size, data type, and complexity of the discrete state of a System object

Methods for Querying Output Specification of System Objects

`getOutputSize`	Get the size of outputs of a System object
`isOutputFixedSize`	Check if outputs of a System object are fixed size
`getOutputDataType`	Get data types of the outputs of a System object
`isOutputComplex`	Check if outputs of a System object are complex

Functions

`sysobjupdate`	Update custom System object to latest syntax (Since R2020b)
`get`	Get states and properties of a System object
`set`	Set values for properties of a System object

Classes

`matlab.System`	Base class for System objects
`matlab.system.mixin.FiniteSource`	Class that adds ability to check for the end of finite data source used by System object
`matlab.system.display.Action`	Create custom button in Block Parameters dialog box for MATLAB System block
`matlab.system.display.Icon`	Specify custom image as icon for MATLAB System block
`matlab.system.display.Header`	Specify header in Block Parameters dialog box for MATLAB System block
`matlab.system.display.SectionGroup`	Create nested groupings of properties in Block Parameters dialog box for MATLAB System block
`matlab.system.display.Section`	Create property group section in Block Parameters dialog box for MATLAB System block

Topics

Getting Started Writing System Objects

Define Basic System Objects

Create a basic System object with the stepImpl method.

Property Attributes

Define Property Attributes

Specify property attributes to limit the type, visibility, and value of properties.

Input and Output

Change the Number of Inputs
This example shows how to set the number of inputs for a System object™ with and without using getNumInputsImpl.
Define Composite System Objects
Define System objects that include other System objects as properties.
Handle Input Specification Changes
Implement methods to restrict when System object input complexity, data type, or size can change or implement a method to react when input specifications change.

Performance and Efficiency

Tips for Defining System Objects
Tips to speed up slow System objects.
Detailed Call Sequence
Call sequence showing the order of methods when you run a System object.
Define Finite Source Objects
This example shows how to define a System object that performs a specific number of steps or specific number of reads from a file.
Save and Load System Object
Use a MATLAB structure to save and load System object properties and state.

Related Information

Customize System Objects for Simulink (Simulink)
System Objects in MATLAB Code Generation (MATLAB Coder)

Featured Examples

Create Moving Average System Object

Walks through how to create a System object that computes a moving average.

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Create New System Objects for File Input and Output

Define new System objects for file input and output.

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Create Composite System Object

Create a System object composed of other System objects.

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