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Enable - Add enabling port to subsystem

Library

Ports & Subsystems

Description

Adding an Enable block to a subsystem makes it an enabled subsystem. A subsystem can contain no more than one Enable block. An enabled subsystem executes while the input received at the Enable port is greater than zero.

At the start of a simulation, Simulink software initializes the states of blocks inside an enabled subsystem to their initial conditions.

Data Type Support

The input for the Enable block is the port that appears on the subsystem in which the Enable block resides. The data type for this input can be any numeric data type that Simulink supports, including fixed-point data types. For more information, see Data Types Supported by Simulink.

Parameters and Dialog Box

States when enabling

When an enabled subsystem executes after being disabled, specify what happens to the states of blocks in the enabled subsystem.

Settings

Default: held

held: Holds the states at their previous values.
reset: Resets the states to their initial conditions (zero if not defined).

Command-Line Information

Parameter: StatesWhenEnabling

Type: string

Value: 'held' | 'reset'

Default: 'held'

Propagate sizes of variable-size signals

Specify when to propagate a variable-size signal.

Settings

Default: Only when enabling

Only when enabling: Propagates variable-size signals only when reenabling the subsystem containing the Enable Port block. When you select this option, sample time must be periodic.
During execution: Propagates variable-size signals at each time step.

Command-Line Information

Parameter: PropagateVarSize

Type: string

Value: 'Only when enabling' | 'During execution'

Default: 'Only when enabling'

Show output port

Select this check box to output the enabling signal.

Settings

Default: On

On: Shows the Enable block output port and outputs the enabling signal. Selecting this option allows the system to process the enabling signal.
Off: Removes the output port from the Enable block.

Command-Line Information

Parameter: ShowOutputPort

Type: string

Value: 'on' | 'off'

Default: 'on'

Enable zero-crossing detection

Select this check box to enable zero-crossing detection.

Settings

Default: On

On: Detects zerocrossings.
Off: Does not detect zerocrossing.

Command-Line Information

Parameter: ZeroCross

Type: string

Value: 'on' | 'off'

Default: 'on'

Characteristics

Sample Time	Determined by the signal at the enable port
Dimensionalized	Yes
Virtual	Yes, if not connected directly to an Outport block For more information, see Virtual Blocks in the Simulink documentation.
Zero-Crossing Detection	Yes, if enabled

Embedded MATLAB Function

Enabled and Triggered Subsystem

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