Using Simulink

Masked Subsystem Example

This simple subsystem models the equation for a line, y = mx + b.

Ordinarily, when you double-click a Subsystem block, the Subsystem block opens, displaying its blocks in a separate window. The mx + b subsystem contains a Gain block, named Slope, whose Gain parameter is specified as m, and a Constant block, named Intercept, whose Constant value parameter is specified as b. These parameters represent the slope and intercept of a line.

This example creates a custom dialog box and icon for the subsystem. One dialog box contains prompts for both the slope and the intercept. After you create the mask, double-click the Subsystem block to open the mask dialog box. The mask dialog box and icon look like this:

A user enters values for Slope and Intercept in the mask dialog box. Simulink makes these values available to all the blocks in the underlying subsystem. Masking this subsystem creates a self-contained functional unit with its own application-specific parameters, Slope and Intercept. The mask maps these mask parameters to the generic parameters of the underlying blocks. The complexity of the subsystem is encapsulated by a new interface that has the look and feel of a built-in Simulink block.

To create a mask for this subsystem, you need to

• Specify the prompts for the mask dialog box parameters. In this example, the mask dialog box has prompts for the slope and intercept.
• Specify the variable name used to store the value of each parameter.
• Enter the documentation of the block, consisting of the block description and the block help text.
• Specify the drawing command that creates the block icon.
• Specify the commands that provide the variables needed by the drawing command (there are none in this example).

About Masks

Creating Mask Dialog Box Prompts