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Group blocks into functional subsystems, create model hierarchy

As a model increases in size and complexity, you can simplify it by grouping blocks into subsystems. A subsystem is a set of blocks that you group into a single Subsystem block.

Using subsystems:

  • Establishes a hierarchical block diagram, where a Subsystem block is on one layer and the blocks that make up the subsystem are on another.

  • Keeps functionally related blocks together.

  • Helps reduce the number of blocks displayed in your model window.

  • Establishes an interface with inputs and outputs.

When you make a copy of a subsystem, that copy is independent of the source subsystem. To reuse the contents of a subsystem across a model or across models, consider referenced subsystems, referenced models, or subsystems linked to a block in a custom library. For more information, see Choose Among Types of Model Components.

A subsystem can be virtual or nonvirtual. A virtual subsystem provides graphical hierarchy in a model and does not impact the execution of a model. A nonvirtual subsystem executes as a single unit within a model.


SubsystemGroup blocks to create model hierarchy


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Simulink.BlockDiagram.createSubsystemCreate subsystem containing specified set of blocks
Simulink.BlockDiagram.copyContentsToSubsystemCopy graphical contents from system to empty subsystem
Simulink.BlockDiagram.expandSubsystemReplace subsystem with subsystem contents
Simulink.SubSystem.convertToModelReferenceConvert subsystem to model reference
Simulink.SubSystem.copyContentsToBlockDiagramCopy graphical contents from subsystem to empty system
Simulink.SubSystem.deleteContentsDelete contents of subsystem


Model Reference Conversion AdvisorConvert subsystems to referenced models
Referenced Files PaneView, save, and close referenced subsystems and models



Create Subsystems

How to create subsystems.

Expand Subsystem Contents

Flatten a model hierarchy by bringing the contents of a subsystem up one level.

Navigate Model Hierarchies

Navigate model hierarchy of subsystems and referenced models.

Preview Content of Model Components

Display representation of block contents on the face of a block.

Subsystem References

Subsystem Reference

Save a subsystem in a separate file and reference it in a model.

Reference a Subsystem File in a Model

Use subsystem reference in a model.

Change Subsystem Reference Component Dynamically Using InitFcn

This example shows how to dynamically change the subsystem reference component using the Initialization Function.