Simulink.VariantControl Class

You can associate a variant control variable of type Simulink.VariantControl with a variant activation time. Simulink.VariantControl variant control variables help you switch variant elements such as blocks and parameters coherently.

Consider a group of blocks that represents a design choice, with each block having the same variant control variable of type Simulink.VariantControl. If you set the variant activation time of these blocks to inherit from Simulink.VariantControl, the blocks inherit the activation time from the variant control variable. As a result, all the blocks have the same activation time and are activated simultaneously to generate rational simulation results and valid code.

You can define Simulink.VariantControl type of control variables in storage locations as listed in Storage Locations for Variant Control Variables (Operands) in Variant Blocks.

Open the slexVariantSubsystems model.

open_system('slexVariantSubsystems');

In the block parameters dialog box of the Controller block:

1. Specify the variant controls, V == 1 and V == 2.

set_param('slexVariantSubsystems/Controller/Linear Controller', 'VariantControl', 'V==1')
set_param('slexVariantSubsystems/Controller/Nonlinear Controller', 'VariantControl', 'V==2')

2. Set Variant activation time to inherit from Simulink.VariantControl to inherit the activation time from V.

set_param('slexVariantSubsystems/Controller', 'VariantActivationTime', 'inherit from Simulink.VariantControl')

In the base workspace, define a Simulink.VariantControl object, V. Set its value to 1, variant activation time to update diagram, and then simulate the model.

V = Simulink.VariantControl('Value', 1, 'ActivationTime', 'update diagram')

V = 
  VariantControl with properties:

             Value: 1
    ActivationTime: 'update diagram'

During simulation, the Controller block inherits the update diagram activation time from V and the Linear Controller block becomes active.

Double-click the Controller block to see the active choice.

sim ('slexVariantSubsystems');

If you change the value of V to 2, the Nonlinear Controller block becomes active during simulation. You can change the value of V using this command or from Simulink.VariantControl dialog box.

V.Value = 2;
sim ('slexVariantSubsystems');

If you change the variant activation time of V to update diagram analyze all choices, the Controller block inherits the update diagram analyze all choices activation time from V. You can observe the inherited activation time using CompiledVariantActivationTime.

V.ActivationTime = 'update diagram analyze all choices';
sim ('slexVariantSubsystems');
get_param('slexVariantSubsystems/Controller', 'CompiledVariantActivationTime')

ans = 
'update diagram analyze all choices'

Numeric values allow you to rapidly prototype variant values when you are still building your model. Numeric values help you focus more on building your variant values than on developing the expressions that activate those choices.

You can define numeric control values in locations listed in Storage Locations for Variant Control Variables (Operands) in Variant Parameters.

Open the slexVariantParameters model.

open_system('slexVariantParameters')

In the MATLAB Editor, specify variant choices in their simplest form as numeric values in Simulink.VariantVariable objects K1 and K2.

K1 = Simulink.VariantVariable('Choices',{'V==1', 3.5, 'V==2', 8.5})

K1 = 
VariantVariable with 2 choices:

Condition	Value
_________	_____
V == 1   	3.5000
V == 2   	8.5000

Specification: ''

Bank: ''

Use getChoice, setChoice, addChoice, removeChoice to access, modify, add or remove choices

K2 = Simulink.VariantVariable('Choices',{'V==1', 4.5, 'V==2', 9.5})

K2 = 
VariantVariable with 2 choices:

Condition	Value
_________	_____
V == 1   	4.5000
V == 2   	9.5000

Specification: ''

Bank: ''

Use getChoice, setChoice, addChoice, removeChoice to access, modify, add or remove choices

Once you successfully create the Simulink.VariantVariable objects, you can modify them by using the methods described in Public Methods or from the VariantVariable dialog box.

Activate one of the variant values by defining a control variable, V, and setting its value to 1 in a Simulink.VariantControl object.

V = Simulink.VariantControl('Value', 1, 'ActivationTime', 'update diagram')

V = 
  VariantControl with properties:

             Value: 1
    ActivationTime: 'update diagram'

When you simulate the model, the condition V == 1 evaluates to true. K1 is assigned a value of 3.5 and K2 is assigned a value of 8.5.

sim ('slexVariantParameters')

If you change the value of V to 2, Simulink® sets the value of K1 and K2 to 4.5 and 9.5 during simulation. You can change the value of V using this command or from Simulink.VariantControl dialog box.

V.Value = 2;
sim ('slexVariantParameters')

Use enumerated types to give meaningful names to integers used as variant control values. For more information on enumerated type data, see Use Enumerated Data in Simulink Models.

In the MATLAB® Editor, define the classes that map enumerated values to meaningful names.

Open the slexVariantParameters model.

open_system('slexVariantParameters')

Specify the variant condition expressions V == EngType.Small and V == EngType.Big in Simulink.VariantVariable objects K1 and K2.

K1 = Simulink.VariantVariable('Choices', {'V == EngType.Small',3.5,'V == EngType.Big',8.5})

K1 = 
VariantVariable with 2 choices:

     Condition     	Value
__________________	_____
V == EngType.Big  	8.5000
V == EngType.Small	3.5000

Specification: ''

Bank: ''

Use getChoice, setChoice, addChoice, removeChoice to access, modify, add or remove choices

K2 = Simulink.VariantVariable('Choices', {'V == EngType.Small',4.5,'V == EngType.Big',9.5})

K2 = 
VariantVariable with 2 choices:

     Condition     	Value
__________________	_____
V == EngType.Big  	9.5000
V == EngType.Small	4.5000

Specification: ''

Bank: ''

Use getChoice, setChoice, addChoice, removeChoice to access, modify, add or remove choices

Here, EngType is an integer-based enumeration class that is derived from the built-in data type, int32. The class has two enumeration values, Small and Big. These enumerated values have underlying integer values 1 and 2. In this example, the enumeration class is defined in the base workspace. You can choose to define the class in other storage locations as listed in Storage Locations for Variant Control Variables (Operands) in Variant Blocks.

type EngType.m

classdef EngType < Simulink.IntEnumType
  enumeration
    Small (1)
    Big (2)
  end
methods (Static)
  function retVal = addClassNameToEnumNames()
      % ADDCLASSNAMETOENUMNAMES Specifies whether to add the class name
      % as a prefix to enumeration member names in generated code.
      % Return true or false.
      % If you do not define this method, no prefix is added.
      retVal = true;
  end
end
end

Once you successfully create the Simulink.VariantVariable objects, you can modify them by using the methods described in Public Methods or from the VariantVariable dialog box.

Activate one of the variant values by defining the control variable V and setting its value to EngType.Small in Simulink.VariantControl object V.

V = Simulink.VariantControl('Value',EngType.Small,'ActivationTime','code compile')

V = 
  VariantControl with properties:

             Value: Small
    ActivationTime: 'code compile'

When you simulate the model, the condition V == 1 evaluates to true. K1 is assigned a value of 3.5, and K2 is assigned a value of 8.5.

sim('slexVariantParameters')

If you change the value of V to 2, Simulink® sets the value of K1 and K2 to 4.5 and 9.5 during simulation. You can change the value of V using this command or from Simulink.VariantControl dialog box.

V.Value = 2

V = 
  VariantControl with properties:

             Value: 2
    ActivationTime: 'code compile'

sim ('slexVariantParameters')

The code that you generate using enumerated types contains the names of the values rather than integers.

% slexVariantParameters_private.h
% #if V == EngType_Big || V == EngType_Small
%     /* Variable: K1 Referenced by: '<Root>/Gain' */
%     #if V == EngType_Big
%       #define rtCP_Gain_K1                   (8.5)
%     #elif V == EngType_Small
%       #define rtCP_Gain_K1                   (3.5)
%     #endif
% #endif
% 
% #if V == EngType_Big || V == EngType_Small
%    /* Variable: K2 Referenced by: '<Root>/Gain1' */
%     #if V == EngType_Big
%       #define rtCP_Gain1_K2                  (9.5)
%     #elif V == EngType_Small
%       #define rtCP_Gain1_K2                  (4.5)
%     #endif
% #endif
% #endif                         /* RTW_HEADER_slexVariantParameters_private_h_ */

Note that for variant parameters with startup activation time, only enumerations that are defined using these techniques are supported:

These enumerations are also supported when permanently stored in a Simulink® data dictionary. See Enumerations in Data Dictionary.

If you intend to generate code for a model containing variant parameters, specify variant control variables as Simulink.Parameter objects. Simulink.Parameter objects allow you to specify other attributes, such as data type and storage class, and control the appearance and placement of variant control variables in generated code.

Open the slexVariantParameters model.

open_system('slexVariantParameters');

In the MATLAB Editor, define a Simulink.Parameter object.

VSS_MODE = Simulink.Parameter;
VSS_MODE.Value = 1;
VSS_MODE.DataType = 'int32';
VSS_MODE.CoderInfo.StorageClass = 'Custom';
VSS_MODE.CoderInfo.CustomStorageClass = 'Define';
VSS_MODE.CoderInfo.CustomAttributes.HeaderFile ='demo_macros.h'; 

Variant control variables defined as Simulink.Parameter objects can have any of the storage classes listed in Storage Classes for Different Variant Activation Times (Simulink Coder).

You can also convert a scalar variant control variable into a Simulink.Parameter object. For more information, see Convert Variant Control Variables into Simulink.Parameter Objects.

Specify the object as a variant control in Simulink.VariantVariable objects K1 and K2.

K1 = Simulink.VariantVariable('Choices',{'V == 1',3.5,'V == 2',8.5});
K2 = Simulink.VariantVariable('Choices',{'V == 1',4.5,'V == 2',9.5});

Once you successfully create the Simulink.VariantVariable objects, you can modify them by using the methods described in Public Methods or from the VariantVariable dialog box.

Activate one of the variant values by defining a Simulink.VariantControl object V and setting its Value property to VSS_MODE.

V = Simulink.VariantControl('Value',copy(VSS_MODE),'ActivationTime','code compile');

When you simulate the model, the condition V == 1 evaluates to true. K1 is assigned a value of 3.5, and K2 is assigned a value of 8.5.

sim('slexVariantParameters');

If you change the value of V to 2, Simulink® sets the value of K1 and K2 to 4.5 and 9.5 during simulation. You can change the value of V using this command or from the Simulink.VariantControl dialog box.

V.Value.Value=2;
sim('slexVariantParameters');

Generate code from the model. For information on how to generate code, see Generate Code Using Embedded Coder (Embedded Coder)

The generated code contains both Linear and Nonlinear choices in preprocessor conditionals #if and #elif because of the code compile activation time. The variant control variable V is defined using a macro — #define directive — in the header file demo_macros.h. You can control the appearance and placement of V in the generated code and prevent optimizations from eliminating storage for V using the storage class property. For more information, see Storage Classes for Different Variant Activation Times (Simulink Coder).

% demo_macros.h
% /* Exported data define */
% 
% /* Definition for custom storage class: Define */
% #define V       2          /* Referenced by:
%                            * '<Root>/Gain'
%                            * '<Root>/Gain1'
%                            */
% #endif                    /* RTW_HEADER_demo_macros_h_ */
% 
% /*

Set the value of a Simulink.VariantControl object to an object of a user-defined data class that derives from Simulink.Parameter. The user-defined class package that contains the class definition must be available on the MATLAB® search path. Data objects that you create from your package can use the storage classes that the package defines. For an example that shows how to create a data class in a package, see Define Data Classes.

open_system("slexVariantParameters");

/* myParams.h */
/* Declaration for custom storage class: myPackage_ExportedGlobal */
extern int32_T V;

/* myParams.c */
/* Exported data definition */
/* Definition for custom storage class: myPackage_ExportedGlobal */
int32_T V = 1;