Conditionally Executed Subsystems and Models

Control when a subsystem or model is executed

A conditionally executed subsystem or conditionally executed referenced model runs:

  • Once at the current time step when enabled or triggered by an external signal

  • One or more times during a time step when receiving a function-call event.

The external signal, called the control signal, is attached to the control input port.

For subsystems that run after evaluating a condition, see Logical Conditionally Executed Subsystems.

Blocks

expand all

Enabled SubsystemSubsystem whose execution is enabled by external input
Triggered SubsystemSubsystem whose execution is triggered by external input
Enabled and Triggered SubsystemSubsystem whose execution is enabled and triggered by external inputs
EnableAdd enable port to subsystem or model
TriggerAdd trigger or function port to subsystem or model
Function-Call SubsystemSubsystem whose execution is controlled by an external function-call input
Function-Call GeneratorProvide function-call events to control execution of a subsystem or model
Function-Call SplitProvide junction for splitting function-call line
Function-Call Feedback LatchBreak feedback loop involving data signals between function-call blocks
TriggerAdd trigger or function port to subsystem or model

Topics

Introduction

Conditionally Executed Subsystems Overview

Overview of conditionally executed subsystems.

Modify Referenced Models for Conditional Execution

Execute referenced models conditionally, similar to conditionally executed subsystems.

Ensure Outport is Virtual

Option on a conditional subsystem or root-level Outport block.

Enabled and Triggered Subsystems

Using Enabled Subsystems

Create a subsystem that executes when a control signal has a positive value.

Using Triggered Subsystems

Create a subsystem that executes with a trigger signal.

Using Enabled and Triggered Subsystems

Create a subsystem that executes with a trigger signal or control signal with a positive value.

Function-Call Subsystems

Using Function-Call Subsystems

Create a subsystem that executes with a function call.

Subsystem Output Initialization

Conditional Subsystem Initial Output Values

Specify initial output values for a conditional subsystem.

Conditional Subsystem Output Values When Disabled

Specify output behavior when conditional subsystem is disabled.

Simplified Initialization Mode

Control initial values for conditional subsystems.

Featured Examples

Enabled Subsystems

Enabled Subsystems

What happens when a sine wave is fed into an enabled subsystem. After running the simulation, the scope shows three plots.

Open Model
Advanced Enabled Subsystems

Advanced Enabled Subsystems

What happens when a sine wave is fed into an enabled subsystem. The four subsystems in the model contain integrators, either discrete or continuous as described by the Subsystem name. After running the simulation, the two scopes show the results for the discrete enabled subsystems (top scope) and continuous enabled subsystems (bottom scope.)

Open Model
Triggered Subsystems

Triggered Subsystems

Triggered subsystems and describes the different trigger types. A triggered subsystem is executed for a single time step whenever the trigger port transitions from false to true in a specified direction. The transition of the trigger port may occur when the direction of the transition is rising, falling, or both rising and falling. A rising transition occurs when the trigger signal transitions from zero or below to a positive value. A falling transition occurs when the trigger signal transitions from zero or above to a negative value.

Open Model
Discrete and Continuous Resettable Subsystems

Discrete and Continuous Resettable Subsystems

The comparison between behaviors of discrete and continuous resettable subsystems. After running the simulation, the two scopes show the results for the discrete resettable subsystem (top scope), and continuous enabled subsystems (bottom scope).

Open Model
Block Priority

Block Priority

What happens when blocks are assigned different priorities. The block priority affects the order in which the blocks are executed. You can set the block priority through the Block Properties dialog.

Open Model

Simulink Documentation

Support