Set Up Model Variants

Open the example model AutoMRVarAutoMRVar. 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 load function 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 American (USA) emission standard.

AutoMRVar implements the automobile application using the Model Variants block named 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 choices.

Model NameVariant ControlCondition (read only)
GasolUSAGUFUEL==1 && EMIS==1
GasolEuroGEFUEL==1 && EMIS==2
DieselUSADUFUEL==2 && EMIS==1
DieselEuroDEFUEL==2 && EMIS==2

    Note:   You can use condition expressions directly in the Variant control field. You do not need to create Simulink.Variant objects.

Configure the Model Variants Block

You can configure a Model block and specify your variant choices.

  1. Create a model.

  2. From the Ports & Subsystems library, add a Model block to the model.

  3. Right-click the Model block and select Block Parameters (ModelReference) from the context menu.

  4. Under Variant choices, specify the model choices in the Model name column. To specify a protected model, use the extension .slxp or .mdlp. For more information, see Protected Model.

  5. For each model choice, specify the variant control in the Variant control column. Use a Boolean condition expression or a Simulink.Variant object representing a Boolean condition expression.

    You must populate the Variant control column for each choice. You cannot comment out (%) variant control values for the Model block. However, for Variant Subsystem blocks, you can comment out variant choices.

  6. 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.

  7. 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 Referenced Model Simulation Modes.

  8. If you want to add more variant choices, click the Add a new variant button .

  9. After you have specified all you referenced models and added all your variant choices, click OK.

    For next steps, see Set and Open Active Variants.

Disable and Enable Model Variants

You can disable model variants without losing your variant settings. After you enable variants, they remain enabled until you explicitly disable them.

To disable variants from a Model block:

  1. Right-click the block and select Block Parameters (ModelReference) to open the block parameters dialog box.

  2. Click Disable Variants.

Disabling variants:

  • 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 enable variants later, click Enable Variants. The Model block selects an active variant according to the current base workspace variables and conditions.

Parameterize Model Variants

You can apply a parameter to a variant control. Parameter values are the same as for a referenced model. For more information, see Parameterize Model References.

  1. In the block parameters dialog box, under Variant choices, select the row for the variant control that you want to parameterize.

  2. In the Model argument values (for this instance) text box, specify the parameter.

  3. Click Apply.

Additional Examples

For additional examples of model reference variants, in the Help browser, select Simulink > Examples > Modeling Features > Model Reference > Model Reference Variants.

The example sldemo_mdlref_variantssldemo_mdlref_variants shows a model variant.

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