Variant Start - Define start of bounded region - Simulink (original) (raw)

Define start of bounded region

Since R2024a

Libraries:
Simulink / Signal Routing

Description

The Variant Start block defines the start of the bounded region that allows you to limit variant condition propagation without introducing a level of hierarchy. Define the end of the bounded region by using Variant End. For every Variant Start block, there is a single corresponding Variant End block. When you specify the variant conditions on the Variant Start block, the corresponding Variant End block inherits the conditions and other parameters based on the unique Variant Start End Tag on compile.

In a given hierarchy, a region between the outport of a Variant Start block and the corresponding inport of the Variant End block is defined as a bounded region if the following conditions are met:

• You can create a subsystem that wraps all the blocks within the choice without intersecting with the other choice. Thus, there is a clear demarcation of choices.
• You can create a subsystem with only one inport(connected to the outport of theVariant Start block), and only one outport (connected to the outport of the destination). Choices do not branch out of the region.

Examples

Limitations

• The Variant Start block works with time-based, and action signals. You cannot use SimEvents®, Simscape™ Multibody™, or other non-time-based signals with these blocks.
• Including these blocks within the bounded region formed by the Variant Start and Variant End blocks is not supported, as variant conditions could extend beyond the bounded region when their corresponding pair blocks are located outside of it.
  • Goto and From
  • Inport and Outport
  • Data Store Write and Data Store Read
  • Simulink Function and Function Caller
  • State Writer and State Reader
  • State owner block and State Writer
  • Argument Inport and Argument Outport
  • Entity Multicast (SimEvents) and Queue (SimEvents)
• Merging signals from variant choices of a Variant Start block into a bus is not supported; however, they can be routed to separate buses.

Ports

Input

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Input signal to be connected to the active output port.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus | struct

Output

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Output branch that forms the start of the bounded region with corresponding inport of the Variant End block.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus

Output signal from the _N_th branch.

Data Types: single | double | half | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | Boolean | fixed point | enumerated | bus

Parameters

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Unique identifier to identify the correct Variant Start andVariant End pair that form the bounded region, specified as a valid MATLAB identifier. A valid MATLAB identifier is a character vector of alphanumerics (A–Z, a–z, 0–9) and underscores, such that the first character is a letter and the length of the character vector is less than or equal to namelengthmax.

Programmatic Use

The variant control that determines the active variant choice can be any of these types.

• expression — The software chooses the active variant based on the evaluation of the variant conditions. When a condition expression evaluates totrue, the corresponding variant choice becomes active. When a condition expression evaluates to false, the corresponding variant choice becomes inactive. See Switch Between Choices Using Condition Expressions in Variant Blocks.
• label — The software chooses the active variant based on the name of the variant. The variant control is a string and does not require you to create any variable in any workspaces. See Switch Between Choices Using Labels in Variant Blocks.
• sim codegen switching — Automatically switch between the variants for simulation and code generation workflows without creating any workspace variable. When you simulate a model, the software automatically chooses thesim branch as the active choice. Similarly, when you do a software-in-the-loop (SIL) or processor-In-Loop (PIL) simulation, generate code, or use external mode, the software automatically chooses the codegen branch. See Switch Between Choices for Simulation and Code Generation Workflows Without Using Control Variables in Variant Blocks.

For more information on variant control modes, see Introduction to Variant Controls. For a comparison between different types of variant control modes, see Compare Different Types of Variant Control Modes in Variant Blocks.

Dependencies

The availability of different variant activation times depends on the type of theVariant control mode that you specify. TheVariant activation time parameter determines the time when the software sets the active choice. The parameter also determines which variability to include in the generated code. This table explains the variant activation time supported by each variant control mode.

Programmatic Use

This parameter determines which variability to include in the simulation and code generation workflows. For more information, see Activate Variant During Different Stages of Simulation and Code Generation Workflow.

• update diagram — When you execute the model, only the active choice is included in the simulation and the code generation workflow. Generated code contains only the active choice.
• update diagram analyze all choices — When you execute the model, both active and inactive choices are analyzed for consistency across the model. However, only the active choice is included in the simulation and the code generation workflow. Generated code contains only the active choice.
• code compile — When you execute the model, both active and inactive choices are analyzed for consistency across the model, and all choices are included in the simulation and the code generation workflow. Generated code contains both the active and inactive choices enclosed in the preprocessor conditionals #if and #elif. However, the executable built from the generated code contains only active choice.
• startup — When you execute the model, both active and inactive choices are analyzed for consistency across the model, and all choices are included in the simulation and the code generation workflow. With this option, you can improve the speed of iterative simulations using fast restart. For more information, see Run Iterative Simulations Without Recompiling Model for Variant Systems Using Fast Restart. Code generated from the model contains both the active and inactive choices that are enclosed in regular if conditions. The executable built from the generated code also contains both active and inactive choices.
• inherit from Simulink.VariantControl — When you execute the model, the block inherits the activation time from its variant control variables of type Simulink.VariantControl. If a variant block has multiple variant control variables of type Simulink.VariantControl, then all those variables must have the same activation time.

Dependencies

The availability of different variant activation times depends on the type of the variant control mode that you specify. The Variant activation time parameter determines when the software sets the active choice. The parameter also determines which variability to include in the generated code. This table explains the variant activation time supported by each variant control mode.

Programmatic Use

The table has a row for each variant choice connected to the output port of theVariant Start block. If there are no variant choices, the table is empty.

You can use buttons to the left of the Port and associated conditions table to modify the elements in the table.

To...	Click...
Add a new output port: Create a new output port as a variant choice and add an entry for the new choice in the table.
Delete selected port: Delete the selected variant choice from the block and its entry from the table.
Create/Edit selected variant object: Create or edit a Simulink.VariantExpression object for the selected variant choice in the global workspace and specify the variant condition using the Simulink.VariantExpression object parameter dialog box.NoteFor a model that uses the base workspace, this operation creates theSimulink.VariantExpression object in the base workspace, and the object is available only for the current MATLAB session. To permanently store the data, save the object in a MAT file or MATLAB script.

This parameter is read-only.

Number of the output port that is connected to one variant choice upstream of theVariant Start block. This value is read-only.

Click to add a port or to delete an existing one.

A name for a choice, specified as a string.

Dependencies

To enable this parameter, set Variant control mode tolabel.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Example: set_param(gcb, 'VariantControl', 'V == 3'), wheregcb is the variant choice of the Variant Start block.

Example: get_param(gcb, 'VariantControl'), wheregcb is the variant choice of the Variant Start block.

Specify the condition expression to determine the active choice. When a condition expression evaluates to true, the software activates the corresponding variant choice. When a condition expression evaluates tofalse, the software deactivates the corresponding variant choice.

The variant controls can be:

• Boolean condition expression for rapid prototyping. For example,A == 1, A ~= B, A && B == 1, and so on.
• A Simulink.VariantExpression object that contains a condition expression for condition reuse. See Simulink.VariantExpression Objects for Variant Condition Reuse of Variant Blocks.
• Default Variant Choice if none of the choices evaluates totrue.

Here, A and B are operands called as variant control variables. ==,~=, and && are operators in the condition expression. The condition expression can contain one or more such variant control variables and operators. For information on supported types and storage location of variant control variables, see Types of Variant Control Variables (Operands) in Variant Blocks and Storage Locations for Variant Control Variables (Operands) in Variant Blocks. For information on operators, see Types of Operators in Variant Blocks for Different Activation Times.

For more information, see Switch Between Choices Using Condition Expressions in Variant Blocks.

In Variant Assembly Subsystem block, this parameter is a list of auto-generated boolean expressions with Variant control variable on the left-hand side and the members of the Variant enumeration choice are on the right-hand side of the expressions. Both the sides of the expressions are connected with ==. This parameter is read-only.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

To get the block parameter value programmatically, use the get_param function.

Variant Subsystem block:

Example: set_param(gcb, 'VariantControl', 'V == 3'), wheregcb is the variant choice of the Variant Subsystem block.

Example: get_param(gcb, 'VariantControl'), wheregcb is the variant choice of the Variant Subsystem block.

Variant Source and Variant Sink blocks:

Example: set_param(gcb, 'VariantControls', {'A == 1','A == 2'}), where gcb is the Variant Sink or Variant Source block.

Example: get_param(gcb, 'VariantControls'), wheregcb is the Variant Sink or Variant Source block.

This parameter is read-only.

This parameter displays the condition expression specified asSimulink.VariantExpression object. To change or edit the condition expression, use the Simulink.VariantExpression parameter dialog box that appears when you double-click the object in the workspace.

Note

The operands that you specify in a condition expression of typeSimulink.VariantExpression must be defined in the base workspace or a data dictionary. Specifying operands that are defined in the mask or model workspace is not supported.

This list contains the labels of all the variant choices. To set an active choice, select a label from the list. The corresponding choice becomes active. Alternatively, to change the active choice in label mode, you can follow the approaches described in Set Active Choices Using Variant Control Labels.

Dependencies

To enable this parameter, set Variant control mode tolabel.

Programmatic Use

When you select this option, Simulink® annotates the variant condition expression on each port of theVariant Start block.

Programmatic Use

Block Characteristics

Extended Capabilities

Version History

Introduced in R2024a