Fixed-Point Tool Parameters and Dialog Box

The Fixed-Point Tool includes the following components:

  • Main toolbar

  • Model Hierarchy pane

  • Contents pane

  • Dialog pane

Main Toolbar

The Fixed-Point Tool's main toolbar appears near the top of the Fixed-Point Tool window under the Fixed-Point Tool's menu.

The toolbar contains the following buttons that execute commonly used Fixed-Point Tool commands:

ButtonUsage

Open the Fixed-Point Advisor to prepare the model for conversion to fixed point.

Simulate a model and store the run results.

Pause a simulation.

Stop a simulation.

Analyze model and store derived minimum and maximum results.

Propose data types. Propose fraction lengths for specified word lengths or propose word lengths for specified fraction lengths.

Apply accepted data types.

Compare selected runs.

Create a difference plot for the selected signals.

Plot the selected signal.

Create a histogram plot for the selected signal.

The toolbar also contains the Show option:

The Show option specifies the type of results to display in the Contents pane. The Contents pane displays information only after you simulate a system or propose fraction lengths. If there are no results that satisfy a particular filter option, the list will be blank.

Show OptionResult

All results

Displays all results for the selected tree node.

Signal Logging results

For the selected tree node, displays blocks whose output ports have logged signal data. The Fixed-Point tool marks these blocks with the logged signal icon .

Note

You can plot simulation results associated with logged signal data using the Simulation Data Inspector.

Min/Max results

For the selected tree node, displays blocks that record design Min/Max, simulation Min/Max, and overflow data.

Prerequisites: Fixed-point instrumentation mode should not be set to Force Off.

Overflows

For the selected tree node, displays blocks that have non-zero overflows recorded. If a block has its Saturate on integer overflow option selected, overflow information appears in the Saturations column, otherwise it appears in the OverflowWraps column.

Conflicts with proposed data types

For the selected tree node, displays results that have potential data typing or scaling issues.

Prerequisites: This information is available only after you propose data types.

The Fixed-Point Tool marks these results with a yellow or red icon, as shown here:

The proposed data type poses potential issues for this object. Open the Result Details tab to review these issues.

The proposed data type will introduce errors if applied to this object. Open the Result Details tab for details about how to resolve these issues.

Groups that must share the same data type

For the selected tree node, displays blocks that must share the same data type because of data type propagation rules.

Prerequisites: This information is available only after you propose fraction lengths.

The Fixed-Point Tool allocates an identification tag to blocks that must share the same data type. This identification tag is displayed in the DTGroup column as follows:

  • If the selected tree node is the model root

    All results for the model are listed. The DTGroup column is sorted by default so that you can easily view all blocks in a group.

  • If the selected tree node is a subsystem

    The identification tags have a suffix that indicates the total number of results in each group. For example, G2(2) means group G2 has 2 members. This information enables you to see how many members of a group belong to the selected subsystem and which groups share data types across subsystem boundaries.

Model Hierarchy Pane

The Model Hierarchy pane displays a tree-structured view of the Simulink® model hierarchy. The first node in the pane represents a Simulink model. Expanding the root node displays subnodes that represent the model's subsystems, MATLAB Function blocks, Stateflow® charts, and referenced models.

The Fixed-Point Tool's Contents pane displays elements that comprise the object selected in the Model Hierarchy pane. The Dialog pane provides parameters for specifying the selected object's data type override and fixed-point instrumentation mode. You can also specify an object’s data type override and fixed-point instrumentation mode by right-clicking on the object. The Model Hierarchy pane indicates the value of these parameters by displaying the following abbreviations next to the object name:

AbbreviationParameter Value

Fixed-point instrumentation mode

    mmoMinimums, maximums and overflows
    oOverflows only
    foForce off

Data type override

    sclScaled double
    dblDouble
    sglSingle
    offOff

Contents Pane

The Contents pane displays a tabular view of objects that log fixed-point data in the system or subsystem selected in the Model Hierarchy pane. The table rows correspond to model objects, such as blocks, block parameters, and Stateflow data. The table columns correspond to attributes of those objects, such as the data type, design minimum and maximum values, and simulation minimum and maximum values.

The Contents pane displays information only after you simulate a system, analyze the model to derive minimum and maximum values, or propose fraction lengths.

You can control which of the following columns the Fixed-Point Tool displays in this pane. For more information, see Customizing the Contents Pane View.

Column LabelDescription

Accept

Check box that enables you to selectively accept the Fixed-Point Tool's data type proposal.

CompiledDesignMax

Compile-time information for DesignMax.

CompiledDesignMin

Compile-time information for DesignMin.

CompiledDT

Compile-time data type. This data type appears on the signal line in sfix format. See Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).

DerivedMax

Maximum value the Fixed-Point tool derives for this signal from design ranges specified for blocks.

DerivedMin

Minimum value the Fixed-Point tool derives for this signal from design ranges specified for blocks.

DesignMax

Maximum value the block specifies in its parameter dialog box, for example, the value of its Output maximum parameter.

DesignMin

Minimum value the block specifies in its parameter dialog box, for example, the value of its Output minimum parameter.

DivByZero

Number of divide-by-zero instances that occur during simulation.

DTGroup

Identification tag associated with objects that share data types.

InitValueMax

Maximum initial value for a signal or parameter. Some model objects provide parameters that allow you to specify the initial values of their signals. For example, the Constant block includes a Constant value that initializes the block output signal.

Note

The Fixed-Point Tool uses this parameter when it proposes data types.

InitValueMin

Minimum initial value for a signal or parameter. Some model objects provide parameters that allow you to specify the initial values of their signals. For example, the Constant block includes a Constant value that initializes the block output signal.

Note

The Fixed-Point Tool uses this parameter when it proposes data types.

LogSignal

Check box that allows you to enable or disable signal logging for an object.

ModelRequiredMin

Minimum value of a parameter used during simulation. For example, the n-D Lookup Table block uses the Breakpoints and Table data parameters to perform its lookup operation and generate output. In this example, the block uses more than one parameter so the Fixed-Point Tool sets ModelRequiredMin to the minimum of the minimum values of all these parameters.

Note

The Fixed-Point Tool uses this parameter when it proposes data types.

ModelRequiredMax

Maximum value of a parameter used during simulation. For example, the n-D Lookup Table block uses the Breakpoints and Table data parameters to perform its lookup operation and generate output. In this example, the block uses more than one parameter so the Fixed-Point Tool sets ModelRequiredMax to the maximum of the maximum values of all these parameters.

Note

The Fixed-Point Tool uses this parameter when it proposes data types.

Name

Identifies path and name of block.

OverflowWraps

Number of overflows that wrap during simulation.

ProposedDT

Data type that the Fixed-Point Tool proposes.

ProposedMax

Maximum value that results from the data type the Fixed-Point Tool proposes.

ProposedMin

Minimum value that results from the data type the Fixed-Point Tool proposes.

Run

Indicates the run name for these results.

Saturations

Number of overflows that saturate during simulation.

SimDT

Data type the block uses during simulation. This data type appears on the signal line in sfix format. See Fixed-Point Data Type and Scaling Notation (Fixed-Point Designer).

SimMax

Maximum value that occurs during simulation.

SimMin

Minimum value that occurs during simulation.

SpecifiedDT

Data type the block specifies in its parameter dialog box, for example, the value of its Output data type parameter.

Customizing the Contents Pane View

You can customize the Contents pane in the following ways:

Using Column Views

The Fixed-Point Tool provides the following standard Column Views:

View NameColumns ProvidedWhen Does the Fixed-Point Tool Display this View?
Simulation View (default)Name, Run, CompiledDT, SpecifiedDT, SimMin, SimMax, DesignMin, DesignMax, OverflowWraps, SaturationsAfter a simulating minimum and maximum values.
Automatic Data Typing ViewName, Run, CompiledDT, CompiledDesignMax, CompiledDesignMin,Accept, ProposedDT, SpecifiedDT, DesignMin, DesignMax, DerivedMin, DerivedMax, SimMin, SimMax, OverflowWraps, Saturations, ProposedMin, ProposedMaxAfter proposing data types if proposal is based on simulation, derived, and design min/max.
Automatic Data Typing With Simulation Min/Max ViewName, Run, CompiledDT, Accept, ProposedDT, SpecifiedDT, SimMin, SimMax, DesignMin, DesignMax, OverflowWraps, Saturations, ProposedMin, ProposedMaxAfter proposing data types if the proposal is based on simulation and design min/max.
Automatic Data Typing With Derived Min/Max ViewName, Run, CompiledDesignMax, CompiledDesignMin,Accept, ProposedDT, SpecifiedDT, DerivedMin, DerivedMax, ProposedMin, ProposedMaxAfter proposing data types if the proposal is based on design min/max and/or derived min/max.
Data Collection ViewName, Run, CompiledDT, SpecifiedDT, DerivedMin, DerivedMax, SimMin, SimMax, OverflowWraps, Saturations After simulating or deriving minimum and maximum values if the results have simulation min/max, derived min/max, and design min/max.
Derived Min/Max ViewName, Run, CompiledDesignMax, CompiledDesignMin, DerivedMin, DerivedMaxAfter deriving minimum and maximum values.

By selecting Show Details, you can:

  • Customize the standard column views

  • Create your own column views

  • Export and import column views saved in MAT-files, which you can share with other users

  • Reset views to factory settings

    If you upgrade to a new release of Simulink, and the column views available in the Fixed-Point Tool do not match the views described in the documentation, reset your views to factory settings. When you reset all views, the Model Explorer removes all the custom views you have created. Before you reset views to factory settings, export any views that you will want to use in the future.

You can prevent the Fixed-Point Tool from automatically changing the column view of the contents pane by selecting View > Lock Column View in the Fixed-Point Tool menu. For more information on controlling views, see Customize Model Explorer Views.

Changing Column Order and Width

You can alter the order and width of columns that appear in the Contents pane as follows:

  • To move a column, click and drag the head of a column to a new location among the column headers.

  • To make a column wider or narrower, click and drag the right edge of a column header. If you double-click the right edge of a column header, the column width changes to fit its contents.

Sorting by Columns

By default, the Contents pane displays its contents in ascending order of the Name column. You can alter the order in which the Contents pane displays its rows as follows:

  • To sort all the rows in ascending order of another column, click the head of that column.

  • To change the order from ascending to descending, simply click again on the head of that column.

Dialog Pane

Use the Dialog pane to view and change properties associated with the system under design.

The Dialog pane includes the following components:

ComponentDescription
System under designDisplays the system under design for conversion. You can change the selected system by clicking Change.
Fixed-point preparationContains the Fixed-Point Advisor button. Use this button to open the Fixed-Point Advisor to guide you through the tasks to prepare your floating-point model for conversion to fixed point. For more information, see Fixed-Point Advisor.
Configure model settingsContains default configurations that set up run parameters, such as the run name and data type override settings, by clicking a button. For more information, see Configure model settings.
Range collectionContains controls to collect simulation or derived minimum and maximum data for your model.
Automatic data typingContains controls to propose and, optionally, accept data type proposals.
Result Details tabUse this tab to view data type information about the object selected in the Contents pane.

Tips

From the Fixed-Point Tool View menu, you can customize the layout of the Dialog pane. Select:

  • Show Fixed-Point Preparation to show/hide the Fixed-Point Advisor button. By default, the Fixed-Point Tool displays this button.

  • Show Dialog View to show/hide the Dialog pane. By default, the Fixed-Point Tool displays this pane.

  • Settings for selected system to show/hide the Settings for selected system pane. By default, the Fixed-Point Tool displays this pane.

Fixed-Point Advisor

Open the Fixed-Point Advisor to guide you through the tasks to prepare a floating-point model for conversion to fixed point. Use the Fixed-Point Advisor if your model contains blocks that do not support fixed-point data types.

Configure model settings

Use the configurations to set up model-wide data type override and instrumentation settings prior to simulation. The Fixed-Point Tool provides:

  • Frequently-used factory default configurations

  • The ability to add and edit custom configurations

Note

The factory default configurations apply to the whole model. You cannot use these shortcuts to configure subsystems.

Factory Defaults

Factory Default ConfigurationDescription
Range collection using double override

Use this configuration to observe ideal numeric behavior of the model and collect ranges for data type proposals.

This configuration sets:

  • Run name to DoubleOverride

  • Fixed-point instrumentation mode to Minimums, maximums and overflows

  • Data type override to Double

  • Data type override applies to to All numeric types

By default, a button for this configuration appears in the Configure model settings pane.

Range collection with specified data types

Use this configuration to collect ranges of actual model and to validate current behavior.

This configuration sets:

  • Run name to NoOverride

  • Fixed-point instrumentation mode to Minimums, maximums and overflows

  • Data type override to Use local settings

By default, a button for this shortcut appears in the Configure model settings pane.

Remove overrides and disable range collection

Use this configuration to cleanup settings after finishing fixed-point conversion and to restore maximum simulation speed.

This configuration sets:

  • Fixed-point instrumentation mode to Off

  • Data type override to Use local settings

By default, a button for this shortcut appears in the Configure model settings pane.

Advanced settings

Use Advanced settings to add new configurations or edit existing user-defined configurations.

Run name

Specifies the run name

If you use a default configuration to set up a run, the Fixed-Point Tool uses the run name associated with this configuration. You can override the run name by entering a new name in this field.

Tips

  • To store data for multiple runs, provide a different run name for each run. Running two simulations with the same run name overwrites the original run unless you select Merge results from multiple simulations.

  • You can edit the run name in the Contents pane Run column.

For more information, see Run Management (Fixed-Point Designer).

Simulate

Simulates model and stores results.

Action

Simulates the model and stores the results with the run name specified in Run name. The Fixed-Point Tool displays the run name in the Run column of the Contents pane.

Merge instrumentation results from multiple simulations

Control how simulation results are stored

Settings

Default: Off

On

Merges new simulation minimum and maximum results with existing simulation results in the run specified by the run name parameter. Allows you to collect complete range information from multiple test benches. Does not merge signal logging results.

Off

Clears all existing simulation results from the run specified by the run name parameter before displaying new simulation results.

Command-Line Alternative

Parameter: 'MinMaxOverflowArchiveMode'
Type: string
Value: 'Overwrite' | 'Merge'
Default: 'Overwrite'

Tip

Select this parameter to log simulation minimum and maximum values captured over multiple simulations. For more information, see Propose Data Types For Merged Simulation Ranges (Fixed-Point Designer).

Derive ranges for selected system

Derive minimum and maximum values for signals for the selected system.

The Fixed-Point Tool analyzes the selected system to compute derived minimum and maximum values based on design minimum and maximum values specified on blocks. For example, using the Output minimum and Output maximum for block outputs.

Action

Analyzes the selected system to compute derived minimum and maximum information based on the design minimum and maximum values specified on blocks.

By default, the Fixed-Point Tool displays the Derived Min/Max View with the following information in the Contents pane.

Command-Line Alternative

No command line alternative available.

Dependencies

Range analysis:

  • Requires a Fixed-Point Designer™ license.

Propose

Signedness

Select whether you want The Fixed-Point Tool to propose signedness for results in your model. The Fixed-Point Tool proposes signedness based on collected range data and block constraints. By default, the Signedness check box is selected.

When the check box is selected, signals that are always strictly positive get an unsigned data type proposal. If you clear the check box, the Fixed-Point Tool proposes a signed data type for all results that currently specify a floating-point or an inherited output data type unless other constraints are present. If a result specifies a fixed-point output data type, the Fixed-Point Tool will propose a data type with the same signedness as the currently specified data type unless other constraints are present.

Word length or fraction length

Select whether you want the Fixed-Point Tool to propose word lengths or fraction lengths for the objects in your system.

  • If you select Word length, the Fixed-Point Tool proposes a data type with the specified fraction length and the minimum word length to avoid overflows.

  • If you select Fraction length, the Fixed-Point Tool proposes a data type with the specified word length and best-precision fraction length while avoiding overflows.

If a result currently specifies a fixed-point data type, that information will be used in the proposal. If a result specifies a floating-point or inherited output data type, and the Inherited and Floating point check boxes are selected, the Fixed-Point Tool uses the settings specified under Automatic data typing to make a data type proposal.

Propose for

Inherited

Propose data types for results that specify one of the inherited output data types.

Floating-point

Propose data types for results that specify floating-point output data types.

Default fraction length

Specify the default fraction length for objects in your model. The Fixed-Point Tool proposes a data type with the specified fraction length and the minimum word length that avoids overflows.

Command-Line Alternative

No command line alternative available.

Default word length

Specify the default word length for objects in your model. The Fixed-Point Tool will propose best-precision fraction lengths based on the specified default word length.

Command-Line Alternative

No command line alternative available.

When proposing types use

Specify the types of ranges to use for data type proposals.

Design and derived ranges

The Fixed-Point Tool uses the design ranges in conjunction with derived ranges to propose data types. Design ranges take precedence over derived ranges.

Design and simulation ranges

The Fixed-Point Tool uses the design ranges in conjunction with collected simulation ranges to propose data types. Design ranges take precedence over simulation ranges.

The Safety margin for simulation min/max (%) parameter specifies a range that differs from that defined by the simulation range. For more information, see Safety margin for simulation min/max (%)

All collected ranges

The Fixed-Point Tool uses design ranges in addition to derived and simulation ranges to propose data types.

Design minimum and maximum values take precedence over simulation and derived ranges.

Command-Line Alternative

No command line alternative available.

Safety margin for simulation min/max (%)

Specify safety factor for simulation minimum and maximum values.

Settings

Default: 0

The simulation minimum and maximum values are adjusted by the percentage designated by this parameter, allowing you to specify a range different from that obtained from the simulation run. The specified safety margin must be a real number greater than -100. For example, a value of 55 specifies that a range at least 55 percent larger is desired. A value of -15 specifies that a range up to 15 percent smaller is acceptable.

Dependencies

Before performing automatic data typing, you must specify design minimum and maximum values or run a simulation to collect simulation minimum and maximum data, or collect derived minimum and maximum values.

Command-Line Alternative

No command line alternative available.