Reference Protected Models from Third Parties

To deliver a model without revealing its intellectual property, third parties can protect the model before delivery. A protected model is a referenced model that does not support editing. The protected model author chooses whether to enable read-only view, simulation, code generation, and password protection. When an operation is password-protected, the AES-256 encryption technology protects the supporting file contents.

Note

Creating a protected model requires a Simulink^® Coder™ license.

Identify Protected Models

To identify protected models, look for:

Files in the MATLAB^® Files panel with a badge icon and an .slxp extension. Protected models do not appear in the model hierarchy in the Model Explorer.
Model blocks in the Simulink Editor with a badge icon in the lower left corner:

When a Model block specifies a model name without a file extension, and both a protected model (.slxp) and the original model (.slx) with that name are in the same folder, the Model block references the protected model instead of the original model.

Identify Functionality Supported by Protected Model

If available, a protected model report describes the supported functionality. To open the report, use one of these options:

In the MATLAB Files panel, right-click the protected model and click Open Report.
In the Simulink Editor, right-click the protected-model badge icon on the Model block and click Display Report.

Alternatively, use the slxpinfo function. This function provides high-level information about the protected model even when the report is unavailable.

Load Supporting Files for Protected Model

You may receive the protected model on its own, in a project archive, or in a package.

If you receive a project archive (.mlproj), double-click the project archive in the Files panel and specify the destination folder. Alternatively, right-click the project archive and click Extract Here. The project opens, and the extracted files are in a new folder named after the project archive. Optionally, reference the protected model project from another project. For more information, see Componentize Large Projects.

If you receive a protected model or supporting files by another method, follow the provided instructions. For example, you might need to load a MAT file that contains workspace definitions. You can configure a callback function, such as LoadFcn, to load the MAT file automatically. See Customize Model Behavior with Callbacks.

Verify Digital Signature of Protected Model

If the author signed the protected model, verify the digital signature. In the Files panel, double-click the protected model. In the Details pane, the Signed by field indicates the publisher that signed the model and whether the signature is verified by a trusted certificate authority. Verification fails in these cases:

The protected model was changed after it was signed.
The protected model was not signed.
The protected model was signed with an expired certificate.
The protected model was self-signed with a certificate issued by the author.
The protected model was signed with a missing or invalid certificate.
The certificate of the CA is missing in your system or is invalid.

To verify the signature on protected models by default, in the Simulink Settings dialog box, select Verify digital signature of protected model before opening.

View Protected Model Contents

A read-only view lets you view system contents, block parameters, and signal properties.

To open the read-only view, double-click the Model block referencing the protected model or the .slxp file in the Files panel. If the read-only view is password protected, right-click the protected-model badge icon and select Authorize. In the Model view box, enter the password, then click OK.

To navigate the model hierarchy, double-click Model or Subsystem blocks. Alternatively, navigate to the View All tab and select the system that you want to view. You cannot view the content of protected referenced models in the protected model.

To view block parameters and signal properties, select a block or a signal line, respectively.

To search in the read-only view, click the search button. In the box that appears, enter the name or value to search. The elements of the model that the search returns appear highlighted. The search results include the name and parent of each returned element.

Test Protected Model in Isolated Environment

With the protected model, you may receive a harness model, which typically has the suffix _harness. A harness model provides an isolated environment for you to test the protected model. If supporting files are missing, simulating or generating code for the harness model can help identify them.

To create a harness model, right-click the protected model file in the Files panel, then click Create Harness Model. The created harness model is set up for simulation of the protected model.

Reference Protected Model

To reference a protected model:

Check that the protected model is on the MATLAB path.
If you have a harness model, copy the Model block from the harness model into your model. Otherwise, reference the protected model in a new Model block. Set the Model name block parameter to the name of the protected model.
When a Model block references a protected model, the Simulation mode of the block becomes Accelerator. You cannot change this mode.
If the protected model is password protected, right-click the protected-model badge icon on the Model block and click Authorize. In the Model view box, enter the password, then click OK.
Connect signal lines to the Model block that match its input and output port requirements. For more information, see Define Model Reference Interfaces.
Note that a protected model cannot use noninlined S-functions directly or indirectly.
Provide the needed model argument values. For more information, see Configure Referenced Model to Use Model Arguments.

Use Protected Models

To simulate or generate code for a model that references a protected model, use the same platform and compiler used to create the protected model.

Platform — In the protected model report or with the slxpinfo function, check the platform used to create the protected model. For example, win64 indicates that the platform must be a 64-bit version of Windows^®.
Compiler — In the protected model report, click Protected model configuration parameter settings. Then, on the Code Generation pane, check the Toolchain configuration parameter setting. When Toolchain is set to Automatically locate an installed toolchain, the code generator displays the name of the selected toolchain or compiler. For example, MinGW64 indicates that the compiler must be a MinGW^®-w64 compiler. For more information, see Toolchain (Simulink Coder).

To display or change your default compiler, in the MATLAB Command Window, enter mex -setup. For more information, see mex.

When you simulate or generate code for a model that references the protected model, the software stores the protected model as a compiled MEX binary.

Use Models Protected in Previous Releases

In some cases, you can use a protected model from an older Simulink release than your current release. To check the release version used to create a protected model, open the protected model report or use the slxpinfo function.

You cannot use a protected model created in a newer release than your current release. For example, in R2024b, you cannot use a protected model created in R2025a.

When the protected model is created in an older release than your current release, check whether your current release supports the protected model.

Modeling Requirement	Backward Compatibility for Protected Models
Read-only view	Supported with limitations in R2019a and later releases The protected model must have been created in R2018b or a later release. The protected model must have been created within 10 releases of your current release.
Simulation in normal mode	Supported with limitations in R2019a and later releases The protected model must have been created in R2018b or a later release. The protected model must have been created within 10 releases of your current release.
Simulation in accelerator mode	Supported with limitations in R2020a and later releases The protected model must have been created in R2018b or a later release. You must directly simulate the parent of the protected model. Simulating a model hierarchy that contains the parent model as a referenced model is not supported. To interactively simulate the parent model, you must open it as the top model in its own window. For more information, see Navigate Model Hierarchy. The protected model must use Just-in-Time acceleration and must not require C code generation. For more information on acceleration modes, see How Acceleration Modes Work. The protected model must have been created within 10 releases of your current release.
Simulation in SIL or PIL mode	Supported with limitations in R2020b and later releases The protected model contains ERT, ERT-based, AUTOSAR, GRT, or GRT-based code generated in R2018b or a later release. You can run Model block SIL and PIL simulations that reference the protected model. For more information, see Use Protected Models from Previous Releases to Perform SIL Testing and Generate Code (Embedded Coder). If ERT or AUTOSAR code in the protected model requires shared utility code, use `sharedCodeUpdate` (Embedded Coder) to copy the required code to an existing shared utility code folder. For more information, see Cross-Release Shared Utility Code Reuse (Embedded Coder). You cannot use `Simulink.ModelReference.ProtectedModel.addTarget` or `Simulink.ModelReference.ProtectedModel.removeTarget` to add or remove generated code from a protected model created in a different release. The protected model must have been created within 10 releases of your current release.
Simulation in rapid accelerator mode	Not supported
Code generation	Supported with limitations in R2020b and later releases The protected model contains ERT, ERT-based, AUTOSAR, GRT, or GRT-based code generated in R2018b or a later release, with a `Model reference` code interface. For more information, see Use Protected Models from Previous Releases to Perform SIL Testing and Generate Code (Embedded Coder). If ERT or AUTOSAR code in the protected model requires shared utility code, use `sharedCodeUpdate` (Embedded Coder) to copy the required code to an existing shared utility code folder. For more information, see Cross-Release Shared Utility Code Reuse (Embedded Coder). You cannot use `Simulink.ModelReference.ProtectedModel.addTarget` or `Simulink.ModelReference.ProtectedModel.removeTarget` to add or remove generated code from a protected model created in a different release. The protected model must have been created within 10 releases of your current release.

If a protected model does not support your modeling requirements in later releases, use the same Simulink release that was used to create the protected model.