Set Data Types in Requirements Table Blocks
When you create data in a Requirements Table block, you can use the Type property to set the data type. Data can inherit their data types, or be set to built-in, fixed-point, or enumerated data types. Data can also be nonvirtual buses. By default, Requirements Table block data inherit their data type.
For more information about creating data, see Define Data in Requirements Table Blocks.
Specify Data Types
You can specify the data types by using the Symbols pane and Property Inspector, or the Model Explorer.
To specify the data type using the Symbols pane and Property Inspector:
Open the Requirements Table block.
Open the Symbols pane. In the Modeling tab, in the Design Data section, click Symbols Pane.
Right-click the data you want to modify and click Inspect to open the data properties in the Property Inspector.
In the Properties tab, select the data type in the Type property.
To specify the data type using the Model Explorer:
Open the Model Explorer. In the Modeling tab, in the Design Data section, click Model Explorer.
In the Model Hierarchy pane, expand the model tree view and select the Requirements Table block.
Click the data you want to modify.
Select the data type in the Type property.
In the Model Explorer, you can also filter the data type options. In the General tab, click the Show data type assistant button to display the Data Type Assistant. Then choose an option from the Mode drop-down menu. The available data types depend on the mode you select:
|What to Specify
The data type is inherited based on the Scope property:
|Select a supported built-in data type.
Specify the fixed-point data properties.
|Enter the name of a
that you define in the base workspace.
Enter the name of a
You can click the Edit
button to create or modify
|Enter an expression that evaluates to a data type.
Inheriting Data Types
Requirements Table block data can inherit their data types, including fixed-point types, from their connected signals. To set data to inherit its data type:
Select the data in the Model Explorer. Alternatively, select the data in the Symbols pane and open the Property Inspector.
In the Model Explorer or Property Inspector, set Type to
Inherit: Same as Simulink.
Data with the Scope property set to
Output can also
inherit complexity from the information sent to it. To inherit complexity, set Complexity to
After you build the model, the CompiledType column of the Model Explorer shows the actual data type inherited from Simulink. If the expected type matches the inferred type, the Requirements Table block inherits the data type.
Specify Built-In Data Types
In the Model Explorer, when you expand the Data Type Assistant and set
Built in, you can set
Type to these built-in data types. The built-in data types
64-bit double-precision floating point
32-bit single-precision floating point
|A half-precision data type occupies 16 bits of memory, but its floating-point representation enables it to handle wider dynamic ranges than integer or fixed-point data types of the same size. See The Half-Precision Data Type in Simulink (Fixed-Point Designer).
64-bit signed integer
32-bit signed integer
16-bit signed integer
8-bit signed integer
64-bit unsigned integer
32-bit unsigned integer
16-bit unsigned integer
8-bit unsigned integer
Fixed-Point Designer Data Properties
To represent data as fixed-point numbers in Requirements Table blocks, you must install Fixed-Point Designer™.
You can set the following fixed-point properties:
Select whether you want the fixed-point data to be
data can represent positive and negative quantities. Unsigned data represents
positive values only. The default is
Specify the size, in bits, of the word that will hold the quantized integer. Large word sizes represent large quantities with greater precision than small word sizes. Word length can be any integer between 0 and 128 bits. The default is 16.
Specify the method for scaling your fixed-point data to avoid overflow conditions and minimize quantization issues. You can select these scaling modes:
Binary point (default)
The Data Type Assistant displays the Fraction Length parameter, which specifies the binary point location.
Binary points can be positive or negative integers. A positive integer moves the binary point left of the rightmost bit by that amount. For example, an entry of 2 sets the binary point in front of the second bit from the right. A negative integer moves the binary point further right of the rightmost bit by that amount, as in this example:
The default is
Slope and bias
The Data Type Assistant displays the Slope and Bias parameters:
You can enter slope and bias as expressions that contain parameters defined in the MATLAB workspace.
Use binary-point scaling to simplify the implementation of fixed-point numbers in generated code. Operations with fixed-point numbers that use binary-point scaling are performed with simple bit shifts and eliminate the expensive code implementations required for separate slope and bias values.
Data type override
Specify whether the data type override setting is
Off. See Fixed-Point Instrumentation and Data Type Override (Fixed-Point Designer).
Calculate Best-Precision Scaling
Have Simulink automatically calculate best-precision values for both
Binary point and
bias scaling, based on the Minimum and
Maximum properties you specify.
To automatically calculate best precision scaling values:
Specify the Minimum or Maximum properties.
Click Calculate Best-Precision Scaling.
Simulink calculates the scaling values, then displays them in either the Fraction length, or the Slope and Bias fields.
The Minimum and Maximum properties
do not apply to data with the Scope property set to
The software cannot calculate best-precision scaling for these kinds of
Displays information about the fixed-point data that is defined in the Data Type Assistant:
Maximumshow the same values that you specify in the Minimum and Maximum properties.
Representable maximum, and
Precisionshow the minimum value, maximum value, and precision that the fixed-point data 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. To update the values shown in the
Fixed-point details subpane, click Refresh
Clicking Refresh Details does not modify the data. It changes only the display. To apply the displayed values, click Apply or OK.
The Fixed-point details subpane indicates issues resulting from the fixed-point data specification. For example, this subpane shows two issues.
The row labeled
Maximum indicates that the value specified by
the Maximum property is not representable by the
fixed-point data. To fix the issue, make one of these modifications so the
fixed-point data can represent the maximum value:
Decrease the value in the Maximum property.
Increase Word length.
Decrease Fraction length.
The row labeled
Minimum shows the message
evaluate because evaluating the expression
MySymbol, specified by the Minimum property,
does not return a numeric value. When an expression does not evaluate, the
Fixed-point details subpane shows the unevaluated
expression (truncating to 10 characters) in place of the unavailable value. To fix
this issue, define
MySymbol in the base workspace to provide a
If you click Refresh Details, the issue indicators and
descriptions are removed and the value of
MySymbol appears in
place of the unevaluated text.
Enumerated Data Types
In the Model Explorer or the Property Inspector, you can specify enumerated data
explicitly or make the data inherit it. To explicitly set data to an enumerated type,
set Type to
Enum: <class name> and
<class name> with the name of an enumerated data
type that you define in a MATLAB file on the MATLAB path. To inherit the enumerated type from a connected Simulink signal, set Type to
Inherit: Same as
Simulink. You can only inherit enumerated type data when the
Scope property is
Input. For more
information, see Use Enumerated Data in Simulink Models (Simulink).
In the Model Explorer or Property Inspector, when you set Type to
Bus: <object name>, you can set the data type to a
<object name> with the name of the
Simulink.Bus. Requirements Table blocks support only
nonvirtual buses. See Composite Interface Guidelines (Simulink). For Requirements Table block
bus inputs, incoming virtual bus signals are converted to nonvirtual buses.
You can connect bus inputs and outputs from Requirements Table blocks to other bus signals, including:
Blocks that output bus signals, such as Bus Creator blocks.
Blocks that accept bus signals as an input, such as Bus Selector and Gain blocks.
Other Requirements Table blocks.
Expression Data Types
You can specify the types of Requirements Table block data as expressions by using the Model Explorer or the Property Inspector.
To use the Model Explorer, set the Mode property to
Expression. In the Type property, replace
<data type expression> with an expression that
evaluates to a data type.
To use the Property Inspector, double-click the Type property, clear the contents, and enter an expression.
You can use the following expressions:
For example, suppose you want to designate the variable
as an alias for a
single data type to use as an expression in the
Type property of an input data. Create an instance of the
Simulink.AliasType class and set its
property by entering these commands:
myDataType = Simulink.AliasType;
myDataType.BaseType = "single";
In the Property Inspector, enter the data type alias name,
myDataType, as the value in the Type
Requirements Table blocks do not support code generation if one of the data uses an alias type and is variable size. This limitation does not apply to block input, output, or local data. For more information on variable-size data, see Variable size.