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Handling Incompatibilities with Automatic Stubbing

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What Is Automatic Stubbing? Analyzing a Model Using Automatic Stubbing

What Is Automatic Stubbing?

Automatic stubbing allows you to run a test case generation or property-proving analysis on a model that contains elements that the Simulink Design Verifier software does not support.

When you enable automatic stubbing option, the software considers only the interface of the unsupported elements, not their actual behavior. This technique allows the software to complete the analysis. However, the analysis may achieve only partial results if any of the unsupported model elements affect the simulation outcome.

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Analyzing a Model Using Automatic Stubbing

This section describes a workflow for using automatic stubbing, using a simple Simulink model (t1) as an example.

• Checking Model Compatibility

• Turning On Automatic Stubbing

• Reviewing the Results

• Achieving Complete Results

The t1 model contains a Trigonometric Function block, which is not compatible with the Simulink Design Verifier software.

Checking Model Compatibility

From the Model Editor, there are two ways to check whether a model is compatible with the Simulink Design Verifier software:

• Run the Simulink Design Verifier compatibility check by selecting Tools > Design Verifier > Check Model Compatibility.

  

• Select the analysis that you want:

  • Tools > Design Verifier > Generate Tests

  • Tools > Design Verifier > Prove Properties

  The software first checks the compatibility of the model. If the model itself is incompatible, for example, if it uses a variable-step solver, the analysis cannot continue.

  If it finds incompatible elements in the model, the software stops and asks if you want to turn on automatic stubbing.

  

  You can:

  • Save the log file.

  • Continue the analysis.

  • Terminate the analysis.

The Simulation Diagnostics Viewer is also displayed, listing the incompatibilities. (For more information about this dialog box, see Simulation Diagnostics Viewer.)

Turning On Automatic Stubbing

There are two ways to turn on automatic stubbing:

• If you have not turned on automatic stubbing and the analysis finds at least one incompatibility, the analysis stops and asks if you want to turn on automatic stubbing. Click Continue to proceed with the analysis.

• Before starting the analysis, in the Configuration Parameters dialog box, on the main Design Verifier pane, select Automatic stubbing of unsupported block and functions. When you run the analysis, you are notified that stubbing is turned on and the analysis continues.

  

Reviewing the Results

If you ran the analysis with automatic stubbing enabled, make sure to review the results. In this report, you see a table of unsupported blocks that the software encountered.

The Summary report for the t1 example model shows that one objective was satisfied without generating a test case. The software cannot generate the test case because it does not understand the operation of the Trigonometric Function block.

Achieving Complete Results

If your analysis does not achieve complete results because of the stubbing, you can define custom block replacements to give a more precise definition of the unsupported blocks. For more information:

• Defining Custom Block Replacements.

• Enter

  echodemo sldvdemo_blockreplacement_unsupportedblocks 

  to step through the "Block Replacements for Unsupported Models" demo.

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Analyzing Large Models

Approximations

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