Choose Among Types of Model Components

Useful model components have a well-defined scope, perform functionality defined by requirements, and form part of a larger system.

As you define a component, consider these potential requirements.

  • File contention — You can have larger components if only one person is working on each. If you must share components between several people, you should divide the design into smaller logical pieces. If multiple people must edit the same file, see Merge Simulink Models from the Comparison Report.

  • Reusability — If you expect to use a group of blocks multiple times in a model, define the group of blocks in a reusable component. By avoiding duplication, you make maintaining the model easier. To refactor an existing model with duplication, see Refactor Models with the Clone Detector App and Model Transformer Tool (Simulink Check).

  • Code generation — If you must generate standalone code for a physical component, such as a digital controller, you should have one component that represents the physical component and has a well-defined interface.

  • Verification cost — If part of a model changes frequently and has high testing costs, you should manage this part of the model as a component in a separate file. When components are defined in separate files, you can control and trace changes using project source control. For more information on source control, see Configuration Management.

  • Simulation speed — Using different solvers for components with different numerical properties can increase simulation speed. Similarly, grouping blocks based on their sample rate can increase simulation speed. For more information, see Solver Profiler and Improve Simulation Performance Using Performance Advisor.

Simulink Components

The different types of Simulink® components target different sizes and functionalities. For example, referenced models typically contain more than 500 blocks.

Simulink models can use any combination of these component types.

Type of ComponentDefinitionSource of ContentsImplementation in Model
Subsystem

Unique group of blocks with a dynamic interface, which can be visual or functional.

None — Contents must be manually added to each subsystem

Subsystem block
Subsystem reference

Reference to a reusable group of blocks with a dynamic interface, which can be visual or functional.

Subsystem file (.slx) that contains the referenced subsystem

Subsystem Reference block
Model reference

Reference to a model with a well-defined interface, which is functional and independent of the parent model.

Model file (.slx) that contains the referenced model

Model block
Variant system

Multiple implementations of a component with only one active implementation. Variant systems allow you to address different sets of requirements within a single model.

Variant choices can be any other component type, including a combination of component types.

None — Variant choices must be manually added to each variant system

Variant Subsystem block
Linked block, which can be linked to any component that is stored in a library

Linked instance of block that is stored in a library. If you disable the library link, each instance of a linked block can be unique.

When you drag a subsystem reference or model reference from a library into a model, it directly references the subsystem file or model file that defines its contents. It has a library link only when the parent library block has a mask applied directly to it. Typically, you should use model masks, which are saved in the referenced file and do not require a library link.

Library file (.slx) that contains the parent library block, or prototype block

Block with a library link

High-Level Component Selection Guidelines

This flow chart provides a starting point for choosing a component type.

Before implementing a component based on the result from this flow chart, consider additional modeling requirements. For information on component compatibility with modeling requirements, see Compare Capabilities of Model Component Types.

If you expect a subsystem to grow, make it atomic so that it functionally groups the blocks and executes them together. Functionally grouping the blocks makes it easier to convert the subsystem to a referenced model.

See Also

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