Set Data Properties

When you create Stateflow® charts in Simulink®, you can specify data properties in either the Property Inspector or the Model Explorer.

  • To use the Property Inspector:

    1. In the Modeling tab, under Design Data, select Symbols Pane and Property Inspector.

    2. In the Symbols pane, select the data object.

    3. In the Property Inspector pane, edit the data properties.

  • To use the Model Explorer:

    1. In the Modeling tab, under Design Data, select Model Explorer.

    2. In the Contents pane, select the data object.

    3. In the Message pane, edit the data properties.

Properties vary according to the scope and type of the data object. For many data properties, you can enter expressions or parameter values. Using parameters to set properties for many data objects simplifies maintenance of your model because you can update multiple properties by changing a single parameter.

Stateflow Data Properties

You can set these data properties in:

  • The main and Advanced sections of the Property Inspector.

  • The General tab of the Model Explorer.

Name

Name of the data object. For more information, see Rules for Naming Stateflow Objects.

Scope

Location where data resides in memory, relative to its parent.

SettingDescription
Local

Data defined in the current chart only.

Constant

Read-only constant value that is visible to the parent Stateflow object and its children.

Parameter

Constant whose value is defined in the MATLAB® base workspace or derived from a Simulink block parameter that you define and initialize in the parent masked subsystem. The Stateflow data object must have the same name as the MATLAB variable or the Simulink parameter. For more information, see Share Parameters with Simulink and the MATLAB Workspace.

Input

Input argument to a function if the parent is a graphical function, truth table, or MATLAB function. Otherwise, the Simulink model provides the data to the chart through an input port on the Stateflow block. For more information, see Share Input and Output Data with Simulink.

Output

Return value of a function if the parent is a graphical function, truth table, or MATLAB function. Otherwise, the chart provides the data to the Simulink model through an output port on the Stateflow block. For more information, see Share Input and Output Data with Simulink.

Data Store Memory

Data object that binds to a Simulink data store, which is a signal that functions like a global variable. All blocks in a model can access that signal. This binding allows the chart to read and write to the Simulink data store, sharing global data with the model. The Stateflow object must have the same name as the Simulink data store. For more information, see Access Data Store Memory from a Chart.

Temporary

Data that persists during only the execution of a function. For C charts, you can define temporary data only for a graphical function, truth table, or MATLAB function.

Exported

Data from the Simulink model that is made available to external code defined in the Stateflow hierarchy. You can define exported data only for a Stateflow machine.

Imported

Data parented by the Simulink model that you define in external code embedded in the Stateflow machine. You can define imported data only for a Stateflow machine.

Port

Index of the port associated with the data object. This property applies only to input and output data. See Share Input and Output Data with Simulink.

Update Method

Specifies whether a variable updates in discrete or continuous time. This property applies only when the chart is configured for continuous-time simulation. See Continuous-Time Modeling in Stateflow.

Data Must Resolve to Signal Object

Specifies that output or local data explicitly inherits properties from Simulink.Signal objects of the same name in the MATLAB base workspace or the Simulink model workspace. The data can inherit these properties:

  • Size

  • Complexity

  • Type

  • Unit

  • Minimum value

  • Maximum value

  • Initial value

  • Storage class

  • Sampling mode (for Truth Table block output data)

This option is available only when you set the model configuration parameter Signal resolution to a value other than None. For more information, see Resolve Data Properties from Simulink Signal Objects.

Size

Size of the data object. The size can be a scalar value or a MATLAB vector of values.

  • To specify a scalar, set the Size property to 1 or leave the field blank.

  • To specify an n-by-1 column vector, set the Size property to n.

  • To specify a 1-by-n row vector, set the Size property to [1 n].

  • To specify an n-by-m matrix, set the Size property to [n m].

  • To specify an n-dimensional array, set the Size property to [d1 d2dn], where di is the size of the ith dimension.

  • To configure a Stateflow data object to inherit its size from the corresponding Simulink signal or from its definition in the chart, specify a size of –1.

The scope of the data object determines what sizes you can specify. Stateflow data store memory inherits all its properties, including its size, from the Simulink data store to which it is bound. For all other scopes, size can be scalar, vector, or a matrix of n-dimensions. For more information, see Specify Size of Stateflow Data.

You can specify data size through a MATLAB expression that evaluates to a valid size specification. For more information, see Specify Data Size by Using Expressions and Specify Data Properties by Using MATLAB Expressions.

Variable Size

Specifies that the data object changes dimensions during simulation. This option is available for input and output data only when you enable the chart property Support variable-size arrays. For more information, see Declare Variable-Size Data in Stateflow Charts.

Complexity

Specifies whether the data object accepts complex values.

SettingDescription
OffData object does not accept complex values.
OnData object accepts complex values.
InheritedData object inherits the complexity setting from a Simulink block.

The default value is Off. For more information, see Complex Data in Stateflow Charts.

First Index

Index of the first element of the data array. The first index can be any integer. The default value is 0. This property is available only for C charts.

Type

Type of data object. To specify the data type:

  • From the Type drop-down list, select a built-in type.

  • In the Type field, enter an expression that evaluates to a data type.

Additionally, in the Model Explorer, you can open the Data Type Assistant by clicking the Show data type assistant button . Specify a data Mode, and then specify the data type based on that mode. For more information, see Specify Type of Stateflow Data.

You can specify data type through a MATLAB expression that evaluates to a valid type specification. For more information, see Derive Data Types from Other Data Objects and Specify Data Properties by Using MATLAB Expressions.

Note

If you enter an expression for a fixed-point data type, you must specify scaling explicitly. For example, you cannot enter an incomplete specification such as fixdt(1,16) in the Type field. If you do not specify scaling explicitly, an error appears when you try to simulate your model.

Lock Data Type Against Fixed-Point Tools

Prevents replacement of the current fixed-point type with an autoscaled type chosen by the Fixed-Point Tool. For more information, see Autoscaling Using the Fixed-Point Tool (Fixed-Point Designer).

Unit (e.g., m, m/s^2, N*m)

Specifies physical units for input and output data. For more information, see Specify Units for Stateflow Data.

Initial Value

Initial value of the data object. The options for initializing values depend on the scope of the data object.

ScopeSpecify for Initial Value
LocalExpression or parameter defined in the Stateflow hierarchy, MATLAB base workspace, or Simulink masked subsystem.
ConstantConstant value or expression. The expression is evaluated when you update the chart. The resulting value is used as a constant for running the chart.
ParameterYou cannot enter a value. The chart inherits the initial value from the parameter.
InputYou cannot enter a value. The chart inherits the initial value from the Simulink input signal on the designated port.
OutputExpression or parameter defined in the Stateflow hierarchy, MATLAB base workspace, or Simulink masked subsystem.
Data Store MemoryYou cannot enter a value. The chart inherits the initial value from the Simulink data store to which it resolves.

If you do not specify a value, the default value for numeric data is 0. For enumerated data, the default value typically is the first one listed in the enumeration section of the definition. You can specify a different default enumerated value in the methods section of the definition. For more information, see Define Enumerated Data Types.

You can specify an initial value through a MATLAB expression. For more information, see Specify Data Properties by Using MATLAB Expressions.

Allow Initial Value to Resolve to a Parameter

Specifies that local, constant, or output data inherits its initial value from a Simulink parameter in the MATLAB base workspace. For more information, see Initialize Data from the MATLAB Base Workspace.

Limit Range Properties

Range of acceptable values for this data object. Stateflow charts use this range to validate the data object during simulation.

  • Minimum — The smallest value allowed for the data item during simulation. You can enter an expression or parameter that evaluates to a numeric scalar value.

  • Maximum — The largest value allowed for the data item during simulation. You can enter an expression or parameter that evaluates to a numeric scalar value.

The smallest value that you can set for Minimum is -inf. The largest value that you can set for Maximum is inf.

You can specify the minimum and maximum values through a MATLAB expression. For more information, see Specify Data Properties by Using MATLAB Expressions.

Note

A Simulink model uses the Limit range properties to calculate best-precision scaling for fixed-point data types. Before you select Calculate Best-Precision Scaling, specify a minimum or maximum value. For more information, see Calculate Best-Precision Scaling.

Add to Watch Window

Enables watching the data values in the Stateflow Breakpoints and Watch window. For more information, see View Data in the Breakpoints and Watch Window.

Fixed-Point Data Properties

In the Model Explorer, when you set the Data Type Assistant Mode to Fixed point, the Data Type Assistant displays fields for specifying additional information about your fixed-point data.

Signedness

Specifies whether the fixed-point data is Signed or Unsigned. Signed data can represent positive and negative values. Unsigned data represents positive values only. The default setting is Signed.

Word Length

Specifies the bit size of the word that holds the quantized integer. Large word sizes represent large values with greater precision than small word sizes. The default value is 16.

  • Word length can be any integer from 0 through 128 for chart-level data of these scopes:

    • Input

    • Output

    • Parameter

    • Data Store Memory

  • For other Stateflow data, word length can be any integer from 0 through 32.

You can specify the word length through a MATLAB expression. For more information, see Specify Data Properties by Using MATLAB Expressions.

Scaling

Specifies the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization errors. The default method is Binary point scaling.

SettingDescription
Binary point

If you select this mode, the Data Type Assistant displays the Fraction length field, which specifies the binary point location.

Fraction length can be any integer. The default value is 0. A positive integer moves the binary point left of the rightmost bit by that amount. A negative integer moves the binary point farther right of the rightmost bit.

Slope and bias

If you select this mode, the Data Type Assistant displays fields for entering the Slope and Bias for the fixed-point encoding scheme.

Slope can be any positive real number. The default value is 1.0.

Bias can be any real number. The default value is 0.0.

You can enter slope and bias as expressions that contain parameters you define in the MATLAB base workspace.

Whenever possible, use binary-point scaling to simplify the implementation of fixed-point data in generated code. Operations with fixed-point data that use binary-point scaling are performed with simple bit shifts and eliminate expensive code implementations required for separate slope and bias values. For more information about fixed-point scaling, see Scaling (Fixed-Point Designer).

You can specify Fraction length, Slope, and Bias through a MATLAB expression. For more information, see Specify Data Properties by Using MATLAB Expressions.

Data Type Override

Specifies whether to inherit the data type override setting of the Fixed-Point Tool that applies to this model. If the data does not inherit the model-wide setting, the specified data type applies. For more information about the Fixed-Point Tool, see fxptdlg.

Calculate Best-Precision Scaling

Specifies whether to calculate the best-precision values for Binary point and Slope and bias scaling, based on the values in the Minimum and Maximum fields in the Limit range section.

To calculate best-precision scaling values:

  1. Specify Limit range properties.

  2. Click Calculate Best-Precision Scaling.

Simulink software calculates the scaling values and displays them in the Fraction length field or the Slope and Bias fields. For more information, see Constant Scaling for Best Precision (Fixed-Point Designer).

Note

The Limit range properties do not apply to Constant and Parameter scopes. For Constant, Simulink software calculates the scaling values based on the Initial value setting. The software cannot calculate best-precision scaling for data of Parameter scope.

Show Fixed-Point Details

Displays information about the fixed-point data type that is defined in the Data Type Assistant:

  • Minimum and Maximum show the same values that appear in the corresponding Minimum and Maximum fields in the Limit range section.

  • Representable minimum, Representable maximum, and Precision show the minimum value, maximum value, and precision that the fixed-point data type can represent.

If the value of a field cannot be determined without first compiling the model, the Fixed-point details subpane shows the value as Unknown.

The values displayed by the Fixed-point details subpane do not automatically update if you change the values that define the fixed-point data type. To update the values shown in the Fixed-point details subpane, click Refresh Details.

Clicking Refresh Details does not modify the model. It changes only the display. To apply the displayed values, click Apply or OK.

The Fixed-point details subpane indicates any error resulting from the fixed-point data type specification. For example, this figure shows two errors.

The row labeled Maximum indicates that the value specified in the Maximum field of the Limit range section is not representable by the fixed-point data type. To correct the error, make one of these modifications so the fixed-point data type can represent the maximum value:

  • Decrease the value in the Maximum field of the Limit range section.

  • Increase Word length.

  • Decrease Fraction length.

The row labeled Minimum shows the error Cannot evaluate because evaluating the expression MySymbol, specified in the Minimum field of the Limit range section, does not return a numeric value. When an expression does not evaluate successfully, the Fixed-point details subpane shows the unevaluated expression (truncating to 10 characters as needed) in place of the unavailable value. To correct this error, define MySymbol in the base workspace to provide a numeric value. If you click Refresh Details, the error indicator and description are removed and the value of MySymbol appears in place of the unevaluated text.

Logging Properties

You can set logging properties for data in:

  • The Logging section of the Property Inspector.

  • The Logging tab of the Model Explorer.

Log Signal Data

Saves the data value to the MATLAB base workspace during simulation. For more information, see Log Simulation Output for States and Data.

Test Point

Designates the data as a test point. A test point is a signal that you can observe in a Floating Scope block in a model. Data objects can be test points if:

  • Scope is Local.

  • Parent is not a Stateflow machine.

  • Data type is not ml.

For more information, see Monitor Test Points in Stateflow Charts.

Logging Name

Specifies the name associated with logged signal data. Simulink software uses the signal name as its logging name by default. To specify a custom logging name, select Custom from the list box and enter the new name in the adjacent edit field.

Limit Data Points to Last

Limits the amount of data logged to the most recent samples.

Decimation

Limits the amount of data logged by skipping samples. For example, a decimation factor of 2 saves every other sample.

Additional Properties

You can set additional data properties in:

  • The Info tab of the Property Inspector.

  • The Description tab of the Model Explorer.

Save Final Value to Base Workspace

Assigns the value of the data object to a variable of the same name in the MATLAB base workspace at the end of simulation. This option is available only in the Model Explorer for C charts. For more information, see Model Workspaces (Simulink).

Units

Units of measurement associated with the data object. The unit in this field resides with the data object in the Stateflow hierarchy. This property is available only in the Model Explorer for C charts.

Description

Description of the data object. You can enter brief descriptions of data in the hierarchy.

Document Link

Link to online documentation for the data object. You can enter a web URL address or a MATLAB command that displays documentation in a suitable online format, such as an HTML file or text in the MATLAB Command Window. When you click the Document link hyperlink, Stateflow evaluates the link and displays the documentation.

Default Data Property Values

When you leave a property field blank, Stateflow assumes a default value.

PropertyDefault Value
Size

−1 (inherited), for inputs, parameters, and function outputs

1 (scalar), for other data objects

First Index0
Initial Value0.0
Limit Range PropertiesMinimum-inf
 Maximuminf
Fixed-Point Data PropertiesWord length16
 Fraction length0
 Slope1.0
 Bias0.0

Specify Data Properties by Using MATLAB Expressions

In the Property Inspector and Model Explorer, you can enter MATLAB expressions as values for these properties:

Expressions can contain a mix of numeric values, constants, parameters, variables, arithmetic operations, parameters, constants, arithmetic operators, and calls to MATLAB functions. For example, you can use these functions to specify data properties.

Property FunctionDescription
SizesizeReturns the size of a data object
fiReturns a fixed-point numeric object
TypetypeReturns the type of a data object
fixdtReturns a Simulink.NumericType object that describes a fixed-point or floating-point data type
MinimumminReturns the smallest element or elements of an array
MaximummaxReturns the largest element or elements of an array

For more information, see Specify Data Size by Using Expressions and Derive Data Types from Other Data Objects.

See Also

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