What Is a Data Dictionary?
A data dictionary is a persistent repository of data that are relevant to your model. You can also use the base workspace to store design data that are used by your model during simulation. However, a data dictionary provides more capabilities.
The dictionary stores design data, which define parameters and signals, and include data that define the behavior of the model. The dictionary does not store simulation data, which are inputs or outputs of model simulation that enter and exit Inport and Outport blocks.
A data dictionary is not associated with the MATLAB® dictionary data type which is a data structure that associates each key with a corresponding value. For information on the MATLAB dictionary data type, see Dictionaries.
|Dictionary as data source||Entries in a dictionary are persistent. You do not need to reload data during development.|
|Explicit data-model linkage||You can define a data dictionary as the data source for a model. During model simulation and code generation, the model retrieves data from the data dictionary.|
|Change tracking||When you modify an entry, its status is updated in the dictionary and stored as metadata that can be tracked. The dictionary also tracks who made the changes and when. You can also view or revert changes.|
|Entry comparison||Compare values of entries in two dictionaries.|
|Data grouping into reference dictionaries||Partition and organize data items into reference dictionaries.|
|Model-data dependency||Discover how entries are used in the model.|
|Options for fixing a missing variable|
For a variable reported as undefined at compilation time:
|Store and partition reference data||Store and partition data that are relevant to a model, such as equipment specifications, but not used by the model during simulation.|
|Unified interface for defining data||Use the Model Explorer to work with design data in a dictionary.|
|Incremental update in memory||Improved performance and scalability with minimal memory footprint.|
|Requirements traceability linking||Navigate from a data dictionary entry to a location in a requirements document.|
Sections of a Dictionary
A Simulink data dictionary consists of four sections:
Design Data: Contains the variables and data types that define parameters, signals, and design data that determine the behavior of the model. Design data created or imported in a dictionary are stored in this section.
This section can store only certain classes and data types. See Valid Design Data Classes for more information.
Configurations: Contains configuration sets, which are objects of the
Simulink.ConfigSetclass, that determine how the model is configured during simulation. These objects control attributes such as sample time and simulation start time.
When you store configuration sets in a data dictionary, you use configuration references to access the configuration sets. Models that are linked to a dictionary resolve configuration references to configuration sets in the dictionary. For more information about configuration references, see Share a Configuration with Multiple Models.
This section can also store variant configuration objects, which belong to the
Simulink.VariantConfigurationDataclass. These objects store information about variant configurations, active and default variant settings, and definitions of the control variable associated with each configuration.
If you load a configuration set from the data dictionary that contains a component that is not available on your system, the parameters in the missing component are reset to their default values.
Embedded Coder Dictionary: Contains code generation definitions for use with Embedded Coder®. To inspect and modify code definitions stored in a data dictionary, use the Embedded Coder Dictionary (Embedded Coder) not the Model Explorer.
Other Data: Contains information that is relevant to your model but not used by the model during simulation. Use this section to store reference information such as data that describe physical equipment and processes that are represented by your model.
This section can store almost any built-in or custom class or data type. See Invalid Other Data Classes for more information.
Dictionary Usage for Models Created with Different Versions of Simulink
Simulink provides version handling for data dictionaries. When these events occur, Simulink synchronizes data in a dictionary for use with a model regardless of the Simulink version used to create the model:
You link a model to a data dictionary that was saved in a previous version of Simulink– for example, you link a model that you develop in R2018b with a dictionary saved in R2018a.
You open a model that is linked to a data dictionary and was saved in a previous version of Simulink – for example, you developed a model that uses a data dictionary in R2018a and you open that model in R2018b to continue development.
To view the Simulink version in which a data dictionary is saved, in the Current Folder browser, click the data dictionary and find the Saved in Simulink version field in the Details pane. You also have the option to export (save) a data dictionary for use with models created using a different version of Simulink. To use a data dictionary you saved in a newer Simulink version in an older Simulink version, you need to export it first.
To export a data dictionary:
In the Current Folder pane of the MATLAB Command Window, navigate to the location of the data dictionary.
Double-click the name of the dictionary.
In the Model Explorer, right-click the name of the data dictionary. If you have made changes to the dictionary, in the context menu, select Save Changes.
Right-click the name of the data dictionary. In the context menu, select Export to Previous Version.
In the Export Data Dictionary to Previous Version dialog box, specify the previous version of Simulink in which you want to save the model. Specify the folder into which you want Simulink to place the new version of the dictionary. The folder that you specify cannot contain dictionaries that are part of the existing dictionary hierarchy. Then, click OK.
Verify that the new version of the data dictionary exists in the folder that you specified.
Manage and Edit Entries in a Dictionary
To create, modify, and view the entries in a data dictionary, use the Model Explorer. For more information, see Create, Edit, and Manage Workspace Variables and View and Revert Changes to Dictionary Data.
To manage entries in a dictionary programmatically, see Store Data in Dictionary Programmatically.
You can reference one or more dictionaries in a parent dictionary. The data in the referenced dictionaries are visible in the parent dictionary. Use this technique to meaningfully partition data, especially for model reference hierarchies. For more information, see Partition Dictionary Data Using Referenced Dictionaries and Partition Data for Model Reference Hierarchy Using Data Dictionaries.
Import and Export File Formats
|File Format||Import to Dictionary||Export from Dictionary|
Allow Access to Base Workspace
For information about the Enable model access to base workspace property and the Enable dictionary access to base workspace property, see Continue to Use Shared Data in the Base Workspace.
- Determine Where to Store Variables and Objects for Simulink Models
- Using a Data Dictionary to Manage the Data for a Fuel Control System
- Migrate Models to Use Simulink Data Dictionary
- View and Revert Changes to Dictionary Data
- Store Data in Dictionary Programmatically
- Link Test Cases to Requirements Documents (Requirements Toolbox)