Stateflow®

Typing Stateflow^® Data

What Is Data Type?

The term data type refers to the way computers represent numbers in memory. The type determines the amount of storage allocated to data, the method of encoding a data value as a pattern of binary digits, and the operations available for manipulating the data.

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Specifying Data Type and Mode

To specify the type of a Stateflow^® data object:

1. Open the Data properties dialog, as described in Opening the Data Properties Dialog.

2. Select the Scope of the data object for which you want to set the data type.

   For more information, see Properties You Can Set in the General Pane.

3. Click the Show data type assistant button .

   Note   If you know the specific data type you want to use, you can enter the data type directly in the Type field, or select it from the Type drop-down list, instead of using the Data Type Assistant. For more information, see Working with Data Types in the Simulink® software documentation.

4. Choose a Mode in the Data Type Assistant section of the dialog.

   You can choose from these modes for each scope:

   Scope	Data Type Modes
   	Inherit	Built in	Fixed point	Expression	Bus Object
   Local		yes	yes	yes	yes
   Constant		yes	yes	yes
   Parameter	yes	yes	yes	yes
   Input	yes	yes	yes	yes	yes
   Output	yes	yes	yes	yes	yes
   Data Store Memory	yes

5. Based on the mode you select, specify a data type as follows:

   Mode	What To Specify
   Inherit	You cannot specify a value. You inherit the data type from previously defined data, based on the scope you select for the data object: If scope is Input, you inherit the data type from the Simulink input signal on the designated input port (see Sharing Input and Output Data with Simulink® Models). If scope is Output, you inherit the data type from the Simulink output signal on the designated output port (see Sharing Input and Output Data with Simulink® Models). Note   Avoid inheriting data types from output signals. See Avoid Inheriting Output Data Properties from Simulink® Blocks. If scope is Parameter, you inherit the data type from the associated parameter, which you can define in a Simulink model or the MATLAB® workspace (see Sharing Data with Simulink® Models and the MATLAB® Workspace). If scope is Data Store Memory, you inherit the data type from the Simulink data store to which you bind the data object (see Sharing Global Data with Simulink® Models).
   Built in	Select a data type from the drop-down list of supported data types, as described in Built-In Data Types.
   Fixed point	Specify the following information about the fixed-point data: Whether the data is signed or unsigned Word length Scaling mode For information on how to specify these fixed-point data properties, see Fixed-Point Data Properties.
   Expression	Enter an expression that evaluates to a data type in the Type field. You can use these expressions: Alias type from the MATLAB workspace, as described in Typing Data by Using an Alias type operator to specify the type of previously defined data, as described in Deriving Data Types from Previously Defined Data fixdt function to create a Simulink.NumericType object that describes a fixed-point or floating-point data type For more information on how to build expressions in the Data properties dialog, see Entering Expressions and Parameters for Data Properties.
   Bus object	In the Bus object field, enter the name of a Simulink.Bus object to associate with the Stateflow bus object structure. You must define the bus object in the base workspace. If you have not yet defined a bus object, click Edit to create or edit a bus object in the Bus Types Editor. Note   You can also inherit bus object properties from Simulink signals. For more information about Stateflow bus object structures, see Working with Structures and Bus Signals in Stateflow® Charts.

6. Click Apply to save the data type settings.

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Built-In Data Types

You can choose from these built-in data types:

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Inheriting Data Types from Simulink^® Objects

Stateflow data objects of scope Input, Output, Parameter, and Data Store Memory can inherit their data types from Simulink objects, as follows:

To configure these objects to inherit data types, create the corresponding objects in the Simulink model, and then select Inherit: Same as Simulink from the Type drop-down list in the Data properties dialog. For more information, see Specifying Data Type and Mode.

To determine the data types that the objects inherit, build the Simulink model and look at the Compiled Type column for each Stateflow data object in the Model Explorer.

Note   Stateflow blocks in libraries can inherit data types. However, multiple instances of the same library in a model must inherit the same data type.

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Deriving Data Types from Previously Defined Data

You can use the type operator to derive data types from previously defined Stateflow data. In the following example, the Stateflow operator type(x) specifies the data type of the Stateflow local data object y, where x is a local data object of type int32. After you build your model, the Compiled Type column of the Model Explorer displays the type of each data object in the compiled simulation application.

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Typing Data by Using an Alias

You can specify the type of Stateflow data by using a Simulink data type alias (see Simulink.AliasType in the Simulink Reference documentation). After you build your model, the Compiled Type column of the Model Explorer displays the type used in the compiled simulation application. In the following example, you use the alias MyFloat, with BaseType set to single, to type the Stateflow local data y.

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Strong Data Typing with Simulink^® I/O

By default, inputs to and outputs from Stateflow charts are of type double. Input signals from Simulink models convert to the type of the corresponding input data objects in Stateflow charts. Likewise, the data output objects convert to double before they are exported as output signals to Simulink models.

To interface directly with signals of data types other than double without the need for conversion, enable the option Use Strong Data Typing with Simulink I/O for the Stateflow chart (see Specifying Chart Properties). When you enable this option, the Stateflow chart accepts input signals of any data type that Simulink models support, provided that the type of the input signal matches the type of the corresponding Stateflow input data object. Otherwise, you receive a type mismatch error.

Note   For fixed-point data, enable the Use Strong Data Typing with Simulink I/O option to flag mismatches between input or output fixed-point data in Stateflow charts and their counterparts in Simulink models.

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Sharing Data Between Charts and with External Modules

Sizing Stateflow® Data