Working with Test Points :: Working with Signals (Using Simulink)

Using Simulink

Working with Test Points

A test point is a signal that Simulink guarantees to be observable, for example, on a Floating Scope, during a simulation. 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)), that can render signals inaccessible and hence unobservable during simulation.

Designating a Signal as a Test Point

To designate a signal as a test point, check the Test point option on the signal's Signal Properties dialog box (see Signal Properties Dialog Box).

Note If you enable signal logging for a signal, Simulink designates the signal as a test point automatically. This is because a signal must be accessible to be logged (see Enabling Signal Logging for more information).

Note If you set the test point property of a signal in a library that is referenced by a model that is itself referenced by another model, you must update the referenced model by opening and saving it. Otherwise, Simulink cannot log or display the referenced signal.

Using Signal Objects to Designate Test Points

You can use Simulink.Signal objects to designate test points from the MATLAB workspace.This allows you to designate test points in a model without having to modify the model itself. To use a Simulink.Signal object to control a signal's visibility, the following conditions must be true:

The model does not specify the signal as a test point, i.e., the Test point option is unchecked in the Signal Properties dialog box.
The model specifies the signal's storage class as auto (the default), i.e., the Storage class option in the signal's Signal Properties dialog box is set to auto.
A Simulink.Signal object is associated with the signal, i.e., the MATLAB workspace contains a signal object having the same name as the signal.

If all these conditions are true, you can designate the signal as a test point by setting the associated object's storage class property to any value but auto.

Displaying Test Point Indicators

By default, Simulink displays an indicator next to each signal that serves as a test point. These test point indicators enable you to find the test points in a model at a glance.

The appearance of the indicator changes slightly to indicate test points for which signal logging is enabled.

To turn display of test point indicators on or off, select Port/Signal Displays -> Test Point Indicators from the Simulink Format menu.

Documentation Options Displaying Signal Properties