Simulink Reference

Assertion

Check whether a signal is nonzero

Library

Model Verification

Description

The Assertion block checks whether any of the elements of the signal at its input is nonzero. If any element is nonzero, the block does nothing. If any element is zero, the block halts the simulation, by default, and displays an error message. The block's parameter dialog box allows you to

• specify that the block should display an error message when the assertion fails but allow the simulation to continue.
• specify an M-expression to be evaluated when the assertion fails
• enable or disable the assertion

You can also use the Advanced Pane of the Simulation Parameters dialog box to enable or disable all Assertion blocks in a model.

The Assertion block and its companion blocks in the Model Verification library are intended to facilitate creation of self-validating models. For example, you can use model verification blocks to test that signals do not exceed specified limits during simulation. When you are satisfied that a model is correct, you can turn error-checking off by disabling the verification blocks. You do not have to physically remove them from the model. If you need to modify a model, you can temporarily turn the verification blocks back on to ensure that your changes do not break the model.

Data Type Support

The Assertion block accepts input signals of any dimensions and any data type supported by Simulink, as well as fixed-point data types.

For a discussion on the data types supported by Simulink, refer to Data Types Supported by Simulink in the Using Simulink documentation.

Parameters and Dialog Box

Enable Assertion

Unchecking this option disables the Assertion block, that is, causes the model to behave as if the Assertion block did not exist. The Advanced Pane of the Simulation Parameters dialog box allows you to enable or disable all Assertion blocks in a model regardless of the setting of this option.

Simulation callback when assertion fails

An M-expression to be evaluated when the assertion fails.

Stop simulation when assertion fails

If checked, this option causes the Assertion block to halt the simulation when the block's input is zero and display an error message in Simulink's Simulation Diagnostics viewer. Otherwise, the block displays a warning message in the MATLAB command window and continues the simulation.

Characteristics

Direct Feedthrough	No
Sample Time	Inherited from driving block
Scalar Expansion	No
Dimensionalized	Yes
Zero Crossing	No

Algebraic Constraint

Assignment