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Start Fixed-Point Tool




fxptdlg('modelname') starts the Fixed-Point Tool for the Simulink® model specified by modelname. You can also access this tool by the following methods:

  • From the Simulink Analysis menu, select Data Type Design > Fixed-Point Tool.

  • From a subsystem context (right-click) menu, select Fixed-Point Tool.

In conjunction with Fixed-Point Designer™ software, the Fixed-Point Tool provides convenient access to:

  • Model and subsystem parameters that control the signal logging, fixed-point instrumentation mode, and data type override. (see Model Parameters)

  • Plotting capabilities that enable you to plot data that resides in the MATLAB® workspace, namely, simulation results associated with Scope, To Workspace, and root-level Outport blocks, in addition to logged signal data (see Signal Logging)

  • An interactive automatic data typing feature that proposes fixed-point data types for appropriately configured objects in your model, and then allows you to selectively accept and apply the data type proposals

You can launch the Fixed-Point Tool for any system or subsystem, and the tool controls the object selected in its System under design pane. If Fixed-Point Designer software is installed, the Fixed-Point Tool Contents pane displays the name, data type, design minimum and maximum values, minimum and maximum simulation values, and scaling of each model object that logs fixed-point data. Additionally, if a signal saturates or overflows, the tool displays the number of times saturation or overflow occurred. You can display an object's dialog box by right-clicking the appropriate entry in the Contents pane and selecting Properties.

    Note:   The Fixed-Point Tool works only for models that simulate in Normal mode. The tool does not work when you simulate your model in Accelerator or Rapid Accelerator mode.

Overriding Fixed-Point Specifications

Most of the functionality in the Fixed-Point Tool is for use with the Fixed-Point Designer software. However, even if you do not have Fixed-Point Designer software, you can configure data type override settings to simulate a model that specifies fixed-point data types. In this mode, the Simulink software temporarily overrides fixed-point data types with floating-point data types when simulating the model.

    Note:   If you use fi (Fixed-Point Designer) objects or embedded numeric data types in your model or workspace, you might introduce fixed-point data types into your model. You can set fipref (Fixed-Point Designer) to prevent the checkout of a Fixed-Point Designer license.

To simulate a model without using Fixed-Point Designer:

  1. From the Simulink model Analysis menu, select Data Type Design > Fixed-Point Tool.

    The Fixed-Point Tool opens.

  2. Under System under design, select the system you want to convert.

  3. Under Configure model settings, click Advanced settings. In the Advanced Settings dialog box:

    • Set the Fixed-point instrumentation mode parameter to Force off.

    • Set the Data type override parameter to Double or Single.

    • Set the Data type override applies to parameter to All numeric types.

    Click Apply and close the dialog box.

  4. If you use fi objects or embedded numeric data types in your model, set the fipref DataTypeOverride property to TrueDoubles or TrueSingles (to be consistent with the model-wide data type override setting) and the DataTypeOverrideAppliesTo property to All numeric types.

    For example, at the MATLAB command line, enter:

     p = fipref('DataTypeOverride', 'TrueDoubles', ...
    		'DataTypeOverrideAppliesTo', 'AllNumericTypes');

Introduced before R2006a

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