Action Port

Control port for action signal to If Action Subsystem or Switch Case Action Subsystem block

Description

The Action Port block controls the execution of these subsystem blocks:

• If Action Subsystem blocks connected to If blocks.

• Switch Case Action Subsystem blocks connected to Switch Case blocks.

• Simulink based states in Stateflow^® charts. See Create and Edit Simulink Based States (Stateflow).

Parameters

States when execution is resumed — Select handling of internal states

held (default) | reset

Select how to handle internal states when a subsystem with an Action Port block reenables.

held

When the subsystem reenables, retain the previous state values of the subsystem. Previous state values between calls are retained even if you call other subsystem blocks connected to the If or Switch Case block.

reset

When the subsystem reenables, reinitialize the state values.

A subsystem reenables when the logical expression for its action port evaluates to true after having been previously false. In the following example, the Action Port blocks for both subsystems A and B have the States when execution is resumed parameter set to reset.

When case[1] is true, subsystem A is executed. Repeated calls to subsystem A while case [1] continues to be true, does not reset its state values. The same behavior applies to subsystem B.

Programmatic Use

Block Parameter: InitializeStates

Type: character vector

Value: 'held' | 'reset'

Default: 'held'

Propagate sizes of variable-size signals — Select when to propagate a variable-size signal

Only when execution is resumed (default) | During execution

Select when to propagate a variable-size signal.

Only when execution is resumed

Propagate variable-size signals only when reenabling the subsystem containing the Action Port block.

During execution

Propagate variable-size signals at each time step.

Programmatic Use

Block Parameter: PropagateVarSize

Type: character vector

Values: 'Only when execution is resumed' | 'During execution'

Default: 'Only when execution is resumed'

Model Examples

Simulink Subsystem Semantics

This set of examples shows different types of Simulink® Subsystems and what semantics are used when simulating these Subsystems. Each example provides a description of the model and the subtleties governing how it will be executed.

Open Model

If-Then-Else Blocks

The effect of feeding a sine wave into If Action Subsystem blocks. It is designed to illustrate the similarity between the If Action Subsystem block and the Enabled Subsystem block.

Open Model

Modeling Clutch Lock-Up Using If Blocks

Use If/Else subsystems to build a clutch model. An 'If' subsystem models the clutch dynamics in the locked position while an 'Else' subsystem models the unlocked position. One or the other is enabled using the 'If' block. The dot-dashed lines from the 'If' block denote control signals, which are used to enable If/Else (or other conditional) subsystems. Checking any of the boxes on the GUI produces a plot of any of the selected variables (versus time).

Open Model