Open the example model
You can also open the model from the MATLAB® prompt:
addpath([docroot '/toolbox/simulink/ug/examples/variants/mdlref/']); open('AutoMRVar');
The symbol appears in the lower-left corner of the block to indicate that it uses variants. The name of the variant that was active the last time you saved the model appears on the block.
When you change the active variant, the variant block refreshes. The name changes to reflect the current active variant.
When you open the example model, the
loads a MAT-file that populates the base workspace with the variables
and objects used by the model.
The example shows the use of variants for the following cases:
The automobile can use a diesel or a gasoline engine.
Each engine must meet the European or United States (USA) emission standard.
AutoMRVar implements the automobile application
using the Model Variants block
Engine. The Engine block specifies
four referenced models. Each referenced model represents one permutation
of engine fuel and emission standards. The table shows the variant
|Model Name||Variant Control||Condition (read only)|
You can use condition expressions directly in the Variant
control field. You do not need to create
You can configure a Model block and specify your variant choices.
Create a model.
From the Ports & Subsystems library, add a Model block to the model.
Right-click the Model block and select Block Parameters (ModelReference) from the context menu.
Under Variant choices,
specify the model choices in the Model name column.
To specify a protected model, use the extension
For more information, see Protected Model.
Note: You cannot specify a model as the default variant if that model is a variant choice in a Model block. Instead, you can add that model as a variant choice in a Subsystem block, and then specify that model as the default variant.
For each model choice, specify the variant control
in the Variant control column. Use a Boolean
condition expression or a
representing a Boolean condition expression.
Populate the Variant control column for
each choice. You cannot comment out (
control values for the Model block. However, for Variant
Subsystem blocks, you can comment out variant choices.
To edit the condition that determines the active variant choice, click the Create/Edit selected variant button . In the dialog box, enter the condition and click OK.
If you want, specify the model arguments and the Simulation mode. All simulation modes work with model variants. For more information, see Parameterize Model Variants and Simulate Model Referencing Models.
If you want to add more variant choices, click the Add a new variant button .
After you have specified referenced models and added variant choices, click OK.
For next steps, see Working with Variant Choices.
You can disable model variants without losing your variant settings. After you enable variants, they remain enabled until you explicitly disable them.
Hides and ignores the content of the Variant choices section of the dialog box
Retains the active variant as the model name
Ignores subsequent changes to variant control variables and other models, other than the current model
To disable variants from a Model block:
Right-click the block and select Block Parameters (ModelReference) to open the block parameters dialog box.
Click Disable Variants.
To enable variants, click Enable Variants. The Model block selects an active variant according to the current base workspace variables and conditions.
You can apply a parameter to a variant control. Parameter values are the same as for a referenced model.
In the block parameters dialog box, under Variant choices, select the row for the variant control that you want to parameterize.
In the Model argument values (for this instance) text box, specify the parameter.
For more information, see Parameterize Instances of a Reusable Referenced Model.
For additional examples of model reference variants, in the Help browser, select Simulink > Examples > Modeling Features > Model Reference > Model Reference Variants.
a model variant.