Simulink.Parameter - Store, share, and configure parameter values - MATLAB (original) (raw)

Store, share, and configure parameter values

Description

Create a Simulink.Parameter object to set the value of one or more block parameters in a model, such as the Gain parameter of a Gain block. You create the object in a workspace or in a data dictionary. Set the parameter value in the object, then reference the object from the block.

Use a Simulink.Parameter object to:

• Share a value among multiple block parameters.
• Represent an engineering constant or a tunable calibration parameter.
• Separate a parameter value from its data type and other properties.
• Configure parameter data for code generation.

The Value property of the object stores the parameter value. To use the object in a model, set the value of a block parameter to an expression that includes the name of the object. Omit the Value property from the expression. For more information, see Use Parameter Objects.

For more information about block parameters, see Set Block Parameter Values and How Generated Code Stores Internal Signal, State, and Parameter Data (Simulink Coder).

To configure a Simulink.Parameter object as a model argument, the object must be in a model workspace. In a dialog box such as the Model Explorer, selectArgument for the parameter object. For more information, seeConfigure Instance-Specific Values for Block Parameters in a Referenced Model.

Creation

Create a Simulink.Parameter object:

• Directly from a block dialog box or the Property Inspector. See Create, Edit, and Manage Workspace Variables.
• By using the Model Data Editor. Inspect the Parameters tab. Right-click the row that contains a variable, and from the context menu, select .
• By using the Model Explorer. See Create Data Objects from Built-In Data Class Package Simulink.
• By using the Simulink.Parameter function described below.

Syntax

Description

paramObj = Simulink.Parameter returns aSimulink.Parameter object with default property values.

example

paramObj = Simulink.Parameter(`paramValue`) returns a Simulink.Parameter object and initializes theValue property to paramValue.

example

Properties

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Value to use in block parameters, specified as any of these valid values:

• Numeric value
• Boolean value
• Instance of enumerated type
• Structure
• Scalar or array
• Mathematical expression (see Set Variable Value by Using a Mathematical Expression)

If you use a Simulink.Parameter object to set the block parameter value in a reusable referenced model, you can compile and simulate the model as a referenced model with the value for the object left empty (Value set to[]) as long as you provide an explicit value somewhere in the parent model reference hierarchy. In this case, you cannot simulate the model directly. When the value is empty, you must provide the DataType andDimensions for the object. Although you have specified an empty value, the software still synthesizes a Value by using one of these:

• Max
• Min, if you have not specifiedMax
• 1, if you have not specified eitherMin or Max

See Configure Instance-Specific Values for Block Parameters in a Referenced Model.

You can also use MATLAB® syntax to specify the value.

To use a Simulink.Parameter object to store a value of a particular numeric data type, specify the ideal value with the Value property and control the data type with the DataType property.

If you set the Value property by using a typed expression such as single(32.5), the DataType property changes to reflect the new type. A best practice is to use an expression that is not typed to avoid accumulating numerical error through repeated quantizations or data type saturation, especially for fixed-point data types.

If you set the Simulink.Parameter objectValue as a string or character value,Value is stored as a MATLAB string. For limitations on strings asSimulink.Parameter object values, seeSimulink.Parameter in Simulink String Limitations.

Example: 3.15

Example: "mystring"

Example: 1.2 + 3.2i

Example: true

Example: myEnumType.myEnumValue

Example: struct('field1',15,'field2',7.32)

Example: slexpr('myVar + myOtherVar')

Tips

• To more easily edit a large vector, 2-D matrix, or structure that you store in a Simulink.Parameter object, use the Variable Editor. See Create, Edit, and Manage Workspace Variables.
• When you specify an array with three or more dimensions interactively, such as by using the Model Explorer, this property displays the array as an expression that contains a call to the reshape function. To edit the values in the array, modify the first argument of the reshape call, which contains all of the array values in a serialized vector. When you add or remove elements along a dimension, you must also correct the argument that represents the length of the modified dimension.

Data Types: double | single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | struct | fi | enum | string
Complex Number Support: Yes

This property is read-only.

Custom description of the parameter object, specified as a character vector. Use this property to document the significance that the parameter object has in your algorithm.

If you have an Embedded Coder® license, you can configure this description to appear in the generated code as a comment. See Simulink data object descriptions (Embedded Coder).

Example: 'This parameter represents the maximum rotation speed of the engine.'

Data Types: char | string

Data type of the parameter value in the Value property, specified as 'auto' or a character vector. When you simulate the model or generate code, the software casts the value to the specified data type.

If you specify 'auto', the default setting, the parameter object uses the same data type as the block parameters that use the object. See Reduce Maintenance Effort with Data Type Inheritance.

When you set the Value property to something other than adouble number, the object typically sets theDataType property based on the value of theValue property. For example, when you set theValue property to int8(5), the object sets the value of the DataType property to 'int8'.

To explicitly specify a built-in data type (see Data Types Supported by Simulink), specify one of these options:

• 'double'
• 'single'
• 'half'
• 'int8'
• 'uint8'
• 'int16'
• 'uint16'
• 'int32'
• 'uint32'
• 'int64'
• 'uint64'
• 'boolean'
• 'string'

To specify a fixed-point data type, use the fixdt function. For example, specify'fixdt(1,16,5)'.

If you use a Simulink.AliasType or Simulink.NumericType object to create and share custom data types in your model, specify the name of the object.

To specify an enumerated data type, use the name of the type preceded byEnum:. For example, specify 'Enum: myEnumType'.

To specify a Simulink.ValueType object as the data type, use the name of the object preceded by ValueType:. For example, specify 'ValueType: myValueType'.

When you store a structure or array of structures in the Value property of the object, the object sets the DataType property to'struct'. To specify a Simulink.Bus object as the data type, use the name of the bus object preceded by Bus:. For example, specify 'Bus: myBusObject'.

If you set the Simulink.Parameter objectValue as a string, note the limitations in Simulink String Limitations.

When you specify a Simulink.ValueType orSimulink.Bus object as the data type, some properties of theSimulink.Parameter object are ignored. For example, the Min,Max, and Unit properties of theSimulink.Parameter object are ignored. The software uses the corresponding properties of the Simulink.ValueType object or Simulink.BusElement objects in the Simulink.Bus object instead.

Example: 'auto'

Example: 'int8'

Example: 'fixdt(1,16,5)'

Example: 'myAliasTypeObject'

Example: 'string'

Example: 'Enum: myEnumType'

Example: 'ValueType: myValueType'

Example: 'Bus: myBusObject'

Tips

When you edit the data type interactively, to display the Data Type Assistant, click the Show data type assistant button . For more information, see Specify Data Types Using Data Type Assistant.

Data Types: char | string

Minimum value that the Value property of the object can store, specified as a real double scalar.

The default value is empty, which means the parameter value does not have a minimum.

If you store a complex number in the Value property, theMin property applies separately to the real and imaginary parts.

If Value is less than the minimum value or if the minimum value is outside the range of the object data type, the software generates a warning. When updating the diagram or starting a simulation, the software generates an error.

For more information about how the software uses this property, see Specify Minimum and Maximum Values for Block Parameters

Example: -0.92

Dependencies

The software ignores the value of this property when either of these options apply:

• Value specifies a structure.
  To specify minimum values for the structure, setDataType to a Simulink.Bus object and specify a minimum value for each field by using the correspondingSimulink.BusElement objects in theSimulink.Bus object. See Control Field Data Types and Characteristics by Creating Parameter Object.
• DataType specifies aSimulink.ValueType or Simulink.Bus object.
  The software uses the minimum values specified by theSimulink.ValueType object or theSimulink.BusElement objects in theSimulink.Bus object instead.

Tips

For parameter objects with a fixed-point data type, dialog boxes show the stored integerMinimum property, which is the minimum value that the parameter can have, specified as a stored integer value. The value is derived from the real-world minimum value.

Data Types: double

Maximum value that the Value property of the object can store, specified as a real double scalar.

The default value is empty, which means the parameter value does not have a maximum.

If you store a complex number in the Value property, theMax property applies separately to the real and imaginary parts.

If Value is greater than the maximum value or if the maximum value is outside the range of the object data type, the software generates a warning. When updating the diagram or starting a simulation, the software generates an error.

For more information about how the software uses this property, see Specify Minimum and Maximum Values for Block Parameters.

Example: 5.32

Dependencies

The software ignores the value of this property when either of these options apply:

• Value specifies a structure.
  To specify maximum values for the structure, setDataType to a Simulink.Bus object and specify a maximum value for each field by using the correspondingSimulink.BusElement objects in theSimulink.Bus object. See Control Field Data Types and Characteristics by Creating Parameter Object.
• DataType specifies aSimulink.ValueType or Simulink.Bus object.
  The software uses the maximum values specified by theSimulink.ValueType object or theSimulink.BusElement objects in theSimulink.Bus object instead.

Tips

For parameter objects with a fixed-point data type, dialog boxes show the stored integerMaximum property, which is the maximum value that the parameter can have, specified as a stored integer value. The value is derived from the real-world maximum value.

Data Types: double

Physical unit of parameter value, specified as a character vector that describes a valid unit. For more information, see Unit Specification in Simulink Models.

Example: 'degC'

Dependencies

The software ignores the value of this property when DataType specifies a Simulink.ValueType or Simulink.Bus object. The software uses the units specified by theSimulink.ValueType object or theSimulink.BusElement objects in the Simulink.Bus object instead.

Data Types: char | string

Numeric complexity of the parameter value, specified as either'real' or 'complex'. ForSimulink.Parameter objects in the model workspace, use this property to configure the complexity of a model argument. See Configure Instance-Specific Values for Block Parameters in a Referenced Model.

For numeric values, the software derives the complexity from the parameter value that you specify in the Value property. In this case, changing the complexity results in error.

Dependencies

The software ignores the value of this property when any of these options apply:

• Value specifies a mathematical expression.
• Value specifies a structure.
  To specify complexity for the structure, set DataType to aSimulink.Bus object and specify a complexity for each field by using the corresponding Simulink.BusElement objects in theSimulink.Bus object. See Control Field Data Types and Characteristics by Creating Parameter Object.
• DataType specifies aSimulink.ValueType or Simulink.Bus object.
  The software uses the complexity specified by the Simulink.ValueType object or the Simulink.BusElement objects in theSimulink.Bus object instead.

Dimensions of the value stored in the Value property, specified as a row vector, character vector, or string scalar.

When you set the Value property of the object, the object sets the value of the Dimensions property to adouble row vector. The vector is the same vector that the size function returns.

If you are configuring the object as a model argument, and you intend to provide a value for the object elsewhere in the parent model reference hierarchy, you can leave the Value property empty (set to []) and set the Dimensions and Data Type properties explicitly. See Configure Instance-Specific Values for Block Parameters in a Referenced Model.

To use symbolic dimensions, specify a character vector. See Implement Symbolic Dimensions for Array Sizes in Generated Code (Embedded Coder).

Example: [1 3]

Example: '[1 myDimParam]'

Dependencies

• To enable this property, Value must be empty ([]). Otherwise, the software derives the dimensions from theValue property. For example, a value of [3 4;9 8] has dimensions [2 2].
• The software ignores the value of this property whenDataType specifies a Simulink.ValueType object. The software uses the dimensions specified by theSimulink.ValueType object instead.

Data Types: double | char | string

Examples

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In the MATLAB Command Window, create a Simulink.Parameter object.

myParam = Simulink.Parameter;

Assign a numeric value to the Value property.

Specify the minimum and maximum values the parameter can take with theMin and Max properties.

myParam.Min = 10.11; myParam.Max = 25.27;

Open a new Simulink model. Add a Gain block and set itsGain parameter to myParam. During simulation, the Gain parameter uses the value 15.23.

In the MATLAB Command Window, create a Simulink.Parameter object that stores the value 2.52.

myParam = Simulink.Parameter(2.52);

Change the value by accessing the Value property of the object. This technique preserves the values of the other properties of the object.

To reduce model maintenance, you can leave theDataType property at its default value, auto. The parameter object acquires a data type from the block parameter that uses the object.

To reduce the risk of the data type changing when you make changes to signal data types and other data types in your model, you can explicitly specify a data type for the parameter object. For example, when you generate code that exports parameter data to your custom code, explicitly specify a data type for the object.

In the MATLAB Command Window, create a Simulink.Parameter object that stores the value 18.25.

myParam = Simulink.Parameter(18.25);

The expression 18.25 returns the number 18.25 with the double-precision, floating-point data type double. TheValue property stores the number 18.25 with double precision.

Use the DataType property to specify the single-precision data type single.

myParam.DataType = 'single';

When you simulate or generate code, the object casts the value of theValue property, 18.25, to the data type specified by the DataType property,single.

This example shows how to set the value of a parameter object,myParam, to the sum of two other variables, myVar and myOtherVar. With this technique, when you change the values of the independent variables, the software immediately calculates the new value of the parameter object.

Create the two independent variables.

myVar = 5.2; myOtherVar = 9.8;

Create the parameter object.

myParam = Simulink.Parameter;

Set the value of the parameter object to the expression myVar + myOtherVar.

myParam.Value = slexpr('myVar + myOtherVar')

When you simulate or generate code, the expression evaluates to15.

Version History

Introduced before R2006a