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Test Points

What Is a Test Point?

A test point is a signal that Simulink® guarantees to be observable when using a Floating Scope block in a model. Simulink allows you to designate any signal in a model as a test point.

Designating a signal as a test point exempts the signal from model optimizations, such as signal storage reuse (see Signal storage reuse ) and block reduction (see Implement logic signals as Boolean data (vs. double) ). These optimizations render signals inaccessible and hence unobservable during simulation.

Signals designated as test points will not have algebraic loops minimized, even if Minimize algebraic loop occurrences is selected (for more information about algebraic loops, see Algebraic Loops).

Test points are primarily intended for use when generating code from a model with Simulink Coder™. For more information about test points in the context of code generation, see Signals with Test Points.

Marking a signal as a test point has no impact on signal logging that uses the Dataset logging format. For information about logging signals, see Export Signal Data Using Signal Logging.

Designating a Signal as a Test Point

Use one of the following ways to designate a signal as a test point:

  • Open the signal's Signal Properties dialog and check Test Point in the Logging and accessibility section.

  • Resolve the signal to a base workspace Simulink.Signal object whose storage class is SimulinkGlobal.

The second method is more convenient when you want to control test pointing without having to alter the model.

Model Referencing Limitation

Simulink might not log all signals configured for signal logging in a referenced model, if all of these conditions exist:

  • The referenced model sets the Model Configuration Parameters > Data Import/Export > Signal logging format parameter to ModelDataLogs.

  • The referenced model uses a library and you make a change that affects the set of test points in a library, or that changes the set of models that a library references.

To ensure proper signal logging for the referenced model:

  1. Open the referenced model.

  2. Perform an update diagram on the referenced model (for example, by pressing Ctrl+D).

  3. Save the referenced model.

Displaying Test Point Indicators

By default, Simulink displays an indicator on each signal whose Signal Properties > Test point option is enabled. For example, in the following model signals s2 and s3 are test points:

    Note:   Simulink does not display an indicator on a signal that is specified as a test point by a Simulink.Signal object, because such a specification is external to the graphical model.

A signal that is a test point can also be logged. See Export Signal Data Using Signal Logging for information about signal logging. The appearance of the indicator changes to indicate signals for which logging is also enabled.

To turn display of test point indicators on or off, in the Simulink Editor, select or clearDisplay > Signals & Ports > Testpoint & Logging Indicators.

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