Working with Test Points

About Test Points

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).

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Designating a Signal as a Test Point

To specify that a signal whose storage class is Auto is a test point, open the signal's Signal Properties dialog box and select Logging and accessibility > Test point. The signal is now a test point. Selecting or clearing this option has no effect unless the signal's storage class is Auto.

Any signal whose storage class is not Auto is automatically a test point, regardless of the setting of Signal Properties > Logging and accessibility > Test point. You can specify a non-Auto signal storage class in three ways:

• Set Signal Properties > Real-time Workshop > Storage class to anything other than Auto.

• Resolve the signal to a base workspace Simulink.Signal object that specifies a storage class other than Auto.

• Embed a signal object hat specifies a storage class other than Auto on the port where the signal originates.

Using a base workspace signal object to specify that a signal is a test point can be convenient, because it allows you to control testpointing without having to change the model itself. Assigning storage class SimulinkGlobal has exactly the same effect as assigning storage class Auto and selecting Signal Properties > Logging and accessibility > Test point.

See Signal Properties Dialog Box for more information about specifying signal properties.

Test Points in Referenced Models that Use Library Blocks

If you set the test point property of a signal in a library block that is referenced by a model that is itself referenced by another model, you must update the referenced model containing the test pointed signal by opening and saving it. Otherwise, Simulink will be unable to log or display the referenced signal.

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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 Importing and Exporting Data 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, select or clear Port/Signal Displays > Testpoint/Logging Indicators from the Simulink Format menu.

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Initializing Signals and Discrete States

Displaying Signal Properties

Related Products & Applications

• Simulink
• Control Design
• Signal Processing & Communications
• Model-Based Design
• Physical Modeling
• Verification & Validation

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