About Generating a Modelica Representation of an Engineering Model

You can generate a Modelica representation of an Engineering Model, that is, any of:

  • A 3D piping model.
  • A 3D Heating, Ventilation, and Air-Conditioning (HVAC) model.
  • A schematic Piping and Instrumentation Diagram (P&ID) model.

You generate the Modelica representation by building a Dymola behavior (model) using the engineering model in the physical or logical product. This allows you to integrate Modelica features with the engineering model system design.

You can also select to only generate a Modelica representation of a subsystem of the selected engineering model. You can use this to simulate and test only parts of the model, for example, a certain pipe or HVAC construction.

This page discusses:

See Also
Mapping Engineering Model Objects and Parameters to Modelica Libraries
Generating a Modelica Model from an Engineering Model

General Information

The capability consists of two parts:

  • Mapping of the component types used in the engineering model to suitable Modelica classes. For more information, see About Mapping of the Engineering Model Objects.
  • Generation of a Modelica model and Modelica component classes in Dymola Behavior Modeling from the engineering model and components, using this mapping.

You can define your own Modelica classes and use them for mapping. An example is to define Modelica piping classes with heat ports to allow fluid or thermal study of the generated Modelica model.

Important: If a physical model contains both piping and HVAC elements, divide it into subparts so you can work with only piping elements or HVAC elements.

You can only create the mapping by a command, but you can perform the model generation either by a command or by Engineering Knowledge Language (EKL) scripting methods.

Important: You must do some additional work to create a model that can be simulated. See Building a Simulation Model.

When you have generated the mapping, the command Generate from Engineering Model enables you to generate a Modelica behavior (model) of the engineering model and the included components. The Modelica code is automatically generated, and can then be adapted for simulation, or further extended with other Modelica components. You can also select to generate Modelica code for only a subsystem of the engineering model to, for example, study a certain pipe or HVAC structure.

You can also perform the model generation by Engineering Knowledge Language (EKL) scripting methods. The scripting methods are:

  • GenerateBehaviorModelFromPiping for generation from an engineering model
  • GenerateBehaviorModelFromSinglePipingObject for generation from a single engineering model object
Notes: Concerning the scripting:
  • You cannot generate a Modelica representation of an engineering submodel containing more than one piping or HVAC object by scripting.
  • There is always a diagram (with the default layout algorithm) generated when using scripting.
To generate a submodel containing more than one engineering model object or to generate a diagram with another layout algorithm, or no diagram at all, use the command instead of scripting.

Overview of Generated Modelica Representation

As a result of the Modelica model generation, the following are created under the selected target package, if you select the model name of the generated model to be TwoTanks, and depending on if you display hidden classes in the Package Browser or not. Displaying hidden classes is required when you want to build models without using the generated main model. This is for more advanced users.

Note: TwoTanks is a 3D piping example, but a 3D HVAC model or a schematic P&ID model looks the same.

Overview with Protected Classes Hidden

This is the overview seen by most users.

  • A package TwoTanks inserted in a class InternalGenerated. This package contains the following classes generated from one 3D piping model:
    • A base class TwoTanks that is the generated main model, with mapped components from the 3D piping model, and connections between these components. The base class is represented by the icon .
    • Under that base class, a subpackage Medium containing the medium defined for the model.
  • A top-level class TwoTanks that extends from the TwoTanks model in the InternalGenerated package. This top-level model is the model you should work in when you, for example, extend the model or replace components. This top-level model is represented by the same icon as the base class and it is opened by default when generating the model.

Modelica Representation of Engineering Model Components

Engineering model components representations are required for the generation of a Modelica representation of a 3D model.

These representations are stored in the CATIAPiping library. This library is based on the Modelica Standard library. A default mapping, MSLDefaultMapping is automatically loaded if not already defined. The library also contains components to handle Thermal System classes; it provides a complete mapping for thermal systems as well. The MSLDefaultMapping mapping table is used for 3D piping mapping, for mapping of HVAC or schematic P&ID models, other default mapping tables are available.

For engineering model component representation, the CATIAPiping library provides a complete mapping, using the EquivalentPipe representation. You can also define a customized pipe or HVAC duct representation by extending the Prototype Modelica model. (CATIAPiping.Pipes.BaseClasses.Prototype). When thermal systems are involved, the EquivalentPipe_TSXXX representation is used (XXX represents liquid, gas, or mixture states).

Overview with Protected Classes Displayed, For Advanced Users

If you want to build new models using the generated components instead of working with the generated main model, you must display these protected components in the Package Browser to be able to use them. The same is valid if you want to reuse data coming from the physical model in other models. These topics are for advanced users.

To display protected classes in the Package Browser, clear Hide protected classes from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , in the Editor tab.

The same overview as above is displayed in the Package Browser, with the addition of a number of subpackages generated from the engineering model components. These subpackages are located in the InternalGenerated package, in the TwoTanks class, and they are:

Subpackage Containing the following Modelica components generated from 3D Piping Model components
Pipe_Package "Pipes"
Part_Package "Parts" (valves, nozzles, and other parts that fit the network)
Equipment_Package "Equipment"

You can use components from these packages to build new models.

Note: If you only want to use the components, you can use the option to not generate the diagram of the piping model.

If you expand a component in any of the subpackages above, a record Data may appear. This record contains the parameter names and values coming from the physical model for that component, if any.

Note: If any data coming from the physical model is in the form of a numerical value and not an actual name of a physical attribute, then this data is not included in the Data record.

To reuse data coming from the physical model in a new model, instantiate, from the corresponding generated component, the data record by, for example, dragging it from the Package Browser to the diagram of the new model. To connect to the record, you can, from the parameter field in the parameter dialog of the component you want to use the data in, right-click and select Insert Component Reference > Data, and select variable.

Note: The Modelica path of the instantiated record contains the name of the class that corresponds to a physical element.

Naming Rules

The name of the components (valves, tanks) is generated from the instance name in the physical product model. The description of the components is the occurrence path from the physical product model. To comply to Modelica name rules, special characters in names are replaced, and prefixes may be included to ensure unique entities.

Generated Diagram Layer and 3D Representation

The diagram layer is generated from the topology of the engineering model design. The 3D components by default have a picture representation generated from 3D screenshots ("thumbnails") of the 3D shapes.

Note: If the mapping of a component is undefined, that is, the component has been generated without being mapped to any Modelica class, this component is represented by an empty class represented by the following icon, to indicate that this error must be corrected, by for example replacing this class or correcting the mapping:

You can select from four ways to generate (or not generate) the diagram layer:

  • Force-based: This is the default algorithm for 3D piping and HVAC models.
  • Projection: 3D data, including the 3D view point, is used by this algorithm.
  • From Schematics: This selection is used in two cases:
    • If the engineering model is a schematic P&ID model, this is the default algorithm.
    • If the engineering model is a 3D piping or HVAC model, and this model is associated to some P&ID schematics, this algorithm can be selected to reuse the diagram layout from P&ID for the Modelica diagram layer, if possible. (The association means that there must be implement links between each Logical component and its corresponding Physical occurrence.)
  • No Diagram: This option can be used if you only want to use the generated components to build your own model. See Overview with Protected Classes Displayed, For Advanced Users.

The pictures are stored as resources of the generated Modelica model.

Note: You can select to not use the generated thumbnail images for the icons in the diagram, but use the 2D diagram icons instead.

Generated Icon Layer

The icon layer of the generated Modelica model has a different extent value from the diagram layer. Also, a screenshot of the physical product containing the originating engineering model is used for the image of the icon layer.

For subclasses generated from the pipes, the icon layer includes a picture of the engineering model component.

Model Documentation

The generated base model includes annotations with some information about the origin model. That information is available from the documentation editor.

Modifying the Mapping from a Selected Class in the Generated Model

To improve the generated model, you sometimes need to modify the mapping definition of a generated class. To do so, you can, while working in the generated model, open the mapping definition dialog Engineering Modelica Mapping Editor, and then, in the Package Browser, select the generated class. When you do that, the line in the Equipment and Parts list corresponding to the class of the component is highlighted as well, and you can edit that line to modify the mapping of the class.

Handling Replaceable Components

The generated Modelica components are all replaceable. You can replace a component with a more specialized version.

To do so, you must create a dedicated Modelica class extending the class that is currently used.

To make the replacement easier, you can select to generate replaceable components when you map with a Modelica class.

Links and Relations from the Engineering Model to Its Modelica Representation

You can see the relationships between the generated Modelica representation and the original engineering model using the command Links and Relations from the Diagram section of the action bar in the Dymola Behavior Modeling app. For more information about this command, see Assembly Design User´s Guide: Links and Relations.

Note: The links are not bidirectional. You cannot see these links from the Piping & Tubing 3D Design app, the HVAC 3D Design app, or the Functional & Logical Design app.

Updating a Modelica Model Corresponding to a Modified Engineering Model

When the engineering model is modified, you can update the corresponding generated model using any of the following commands:

  • The model generation command Generate from Engineering Model
  • The dedicated update command Update Current Model from Physical Model
  • Any of the generic PLM update commands Update or Update Assistant
    Note: There are conditions for using any generic PLM update command.
For more information, see Updating, from the Physical or Logical Model, a Generated Modelica Model of a Kinematic Mechanism or an Engineering Model.

Building a Simulation Model

The generated Modelica representation of the engineering model is a base for building a simulation model. You can build a simulation model from the main generated model, or you can use the generated component classes to build a new model. The latter is for more advanced users, see Overview with Protected Classes Displayed, For Advanced Users.

Creating a Simulation Model from the Generated Main Model

To be able to simulate the generated main model, you must in most cases do some completion of it. You can also include 3D representation and animation.

Completing the Model

You must yourself complete the generated main model to be able to simulate it. This is done by, for example:

  • Adding missing components required
  • Fix any missing connections, for example, connecting free extremities of pipes to tank components.
  • Supply required parameter and initial values.

Note: Instead of connecting the free extremities of pipes to components, you do the following:
  1. Add connectors and connect the free pipe extremities to them.
  2. Instantiate the model in another class to create a simulation model by connecting to those connectors.

Animation and 3D Representation

You can animate the fluid flow in the pipes when you simulate the main model in Dymola Behavior Modeling in two ways, as fluid flow or as particle flow. The flow animation is "moving stripes", the particle flow animation is spherical particles flowing in the pipes.

For any fluid flow animation to work, the library CATIAPiping must be available in the database.

You select fluid flow or particle flow the following way:

  • To animate fluid flow, make sure that a row Animation is present as a Rigid Pipe type/subtype in the mapping editor, with the class CATIAPiping.Visualizers.CurvedPipeAnimation.
  • To animate fluid flow as particles, make sure that a row Animation is present as a Rigid Pipe type/subtype in the mapping editor, with the class CATIAPiping.Visualizers.CurvedPipeParticleAnimation.
Note: No port and no parameters are required for these usages.

To also see the 3D representation of tanks and other components, the animation must be performed in, for example, Functional & Logical Design, with the Physical data attached to the editor.

Creating a Simulation Model from the Generated Component Classes

You can instantiate components of the generated Modelica component classes (pipes, tanks, valves, and other components) in a new class and connect them to build a new model. In such cases, you only retrieve geometrical information from the engineering model components, and the main generated model is not used at all.

Licenses

To be able to generate a Modelica representation of an engineering model, you must always have the Dymola Behavior Modeling app. You must also have the following apps depending on the engineering model to generate from:

  • For a 3D piping model, you must also have the Piping & Tubing 3D Design app.
  • For a 3D HVAC model, you must also have the HVAC 3D Design app.
  • For a schematic P&ID model, you must also have the Functional & Logical Design app.
    Note: To be able to edit the schematic P&ID model, you must also have the Piping & Tubing Systems Design app.