Exporting a Model to the FMU Format

You can export a model as an FMU (Functional Mock-up Unit) from the Dymola Behavior Modeling app.

Notes:
  • Unless otherwise stated, features are available for both FMI version 1.0 and FMI version 2.0.
  • The settings below are kept between sessions; they are prefilled the next time you export an FMU.

This task shows you how to:

Before you begin: To export to FMU, you must have the Systems FMU Export license. For further information on licensing, see the Dassault Systèmes License Server Essentials Guide.
See Also
About Interfacing Other Simulation Environments

Export by a Command

You can export a model to an FMU format using a command. For more details on selections, see the scripting section below.

  1. Activate a model from the Package Browser.
  2. From the Behavior Tools section of the action bar, click Export to FMU .
    The Export FMU dialog box appears.

    Class to Export displays the selected class to export.

  3. To select the name and location for the FMU, do the following:
    1. Click after the Output file name field to open the Modelica Class FMU export dialog box.
      The Modelica Class FMU Export dialog box appears.
    2. Browse to the location where the exported FMU is to be located.
    3. Optional: Enter a name for the new FMU file. By default, the name of the Modelica model is proposed.

      Important: The FMU file name must only contain letters, digits, and underscores. It must not begin with a digit.

    4. Click Save to validate and close the Modelica Class FMU Export dialog box.
    The path is inserted in the Export FMU dialog box.
    Tip: You can also edit the Output file name by typing.
  4. Optional: Select the FMI type to use:
    • Model exchange to export the model as model exchange.
    • Co-simulation using Cvode to export the model as Co-simulation with the Cvode solver.
    • Model exchange, and Co-simulation using Cvode to export both as model exchange, and Co-simulation using the Cvode solver.
    • Co-simulation using Dymola solvers to export the model as Co-simulation with the current Dymola solver and tolerance.
      Note: This option is only available for FMI 1.0.

    By default, Model exchange, and Co-simulation using Cvode is selected.

  5. Select the complaint version:.
    • Export as FMI 1.0 if you want to export an FMU compliant with FMI version 1.0.
    • Export as FMI 2.0 if you want to export an FMU compliant with FMI version 2.0.

    By default, Export as FMI 2.0 is selected.

  6. Optional: Select options:

    Note: Only one of the two first options can be selected.

    1. Include source code to include the source code in the exported FMU.

      By default, this option is not selected.

      Note: This option and Store result in mat file (see below) are mutually exclusive, you can only activate one of them at the same time.

    2. Export with string parameters

      Note: String variables are not supported.

      By default, this option is not selected.

    3. Copy resources to FMU to copy the external resources that are using the functions Modelica.Utilites.Files.loadResources or ModelicaServices.ExternalReferences.loadResource to the FMU.

      The FMU is larger because of this. If this is not wanted, clearing the setting prevents copying, but resource-paths using Windows-shares are changed to UNC-paths when possible. This makes the FMU usable within a company - without increasing its size.

      By default, copying external resources to the FMU is not selected.

  7. To select what variables to expose in the exported FMU, do any of the following:
    • To expose all variables in the imported FMU, select All variables, then skip the next step.
      Important: "All variables" means all variables filtered, that is, the model description filters are also taken into account. See Step 11.
    • To specify in detail what variables to expose, click Custom. See next step for selection.
  8. To specify what variables to expose when you have selected Custom in the previous step, click Select variables to display a dialog for selection.

    In the dialog, by default, all variables filtered are selected to be exposed.

    1. In the left part of the dialog, select the variables to hide.

      You can:

      • Search for variables by typing in the first field.
      • Expand and collapse nodes in the tree individually, or all by clicking Expand All or Collapse All.
      • Multiselect variables individually, or all by clicking Select All or Select None.

    2. Click Hide to hide the selected variables.

      Tip: To instead work with what variables to expose, do the following:
      1. In the left part of the dialog, click Select All.
      2. Click Hide.
      You can now work with what variables to expose in the same way as working with what variables to hide.

    3. When you have finalized the selection, click OK to validate the selection and close the dialog box.
  9. Optional: You can store the results in a .mat file.

    This option specifies that the FMU should generate a results file <model id>.mat when the model is imported and simulated, where <model id> is given at FMU initialization. This is useful when importing an FMU with parameter allVariables=false, since it provides a way to still obtain the result for all variables.

    1. Activate Store result in mat file.

      By default, this option is not activated.

      Note: This option and Include source code (see above) are mutually exclusive, you can only activate one of them at the same time.

    2. If the store option is activated, you can specify the result generation interval when storing simulation results by changing the Interval.

      By default, the interval is specified to 0.001 seconds.

  10. Select binaries:
    1. 64-bit binaries if you want to create 64-bit binaries.
    2. 32-bit binaries if you want to create 32-bit binaries.
    3. Linux 64-bit binaries if you want to, on Windows, create Linux 64-bit binaries.

      Note: The option to create Linux binaries can only be activated if:
      • "Windows Subsystems for Linux" is installed on your computer.
      • You have activated the option Enable WSL using: <path to wsl.exe>, with the correct path specified, from Me > Preferences > App Preferences > 3D Modeling > Systems Modeling and Execution > Dymola Behavior Modeling , the Compiler tab. For more information, see Native Apps Preferences Guide: Compiler.

    By default, the first two options are selected.

  11. Optional: Select model description filters to control the filtering of the model description (modelDescription.xml).
    1. Exclude Protected variables to filter away protected Modelica variables.

      By default, this option is selected. This corresponds to the flag Advanced.FMI.xmlIgnoreProtected=true;.

    2. Exclude Auxiliary variables to do the following:

      The option works differently in FMI 2.0 and FMI 1.0:

      • For FMI version 2.0, to filer away all variables of causality local, except states and derivatives of states.
      • For FMI version 1.0, to filter away all variables of causality internal, except the ones with variability parameters.

      By default, this option is not selected. This corresponds to the flag Advanced.FMI.xmlIgnoreLocal=false;.

    3. Only Black-box to do the following:

      The option works differently in FMI 2.0 and FMI 1.0:

      • For FMI version 2.0, to filter away all variables, except the following:
        • Variables of causality inputs and outputs.
        • Variables required for the model structure. The names are however hidden (concealed).
      • For FMI version 1.0, to filter away all variables of causality inputs and outputs.

      By default, this option is not selected. This corresponds to the flag Advanced.FMI.BlackBoxModelDescription=false;.

      Note: If you select Only Black-box, the options Exclude Protected variables and Exclude Auxiliary variables are not selectable anymore; they are not relevant in this case.

  12. Optional: You can select to include a model image in the FMU export:

    If you select to include an image, it is stored in the exported FMU resources with the name model.png.

    Note: This means that you can yourself replace this image with another image with this name.

    • None - no image is included. This is the default selection.
    • Icon - the icon of the model is included.
    • Diagram - the image of the diagram layer is included.
  13. Click OK.
    The model is exported:
    • A progress bar appears.
    • The Message Reporting window appears to let you know the export result.
    • If the export is successful, the .fmu file containing .dll resources is created in the selected directory.

Export by Scripting

You can export a model to FMU format using scripting.

Notes:
Important: To export FMUs with string parameters, you must set the flag Advanced.AllowStringParameters = true;. The flag is by default false. Note that string variables are not supported.

  1. Open the Modelica Scripting window.

    Note: For more information about the creating and executing scripts, see Create and Execute a Script.

  2. Use the scripting function translateModelFMU(modelToOpen, storeResult, modelName, fmiVersion, fmiType, includeSource, includeImage, includeVariables).
    1. Set modelToOpen to the name of the model to be exported, including the path, for example modelToOpen="Modelica.Blocks.Examples.PID_Controller"
    2. Set storeResult=true if the FMU is to generate a results file <model id>.mat when the model is imported and simulated. <model id> is given at FMU initialization. This is useful when importing FMUs with parameter allVariables=false, since it provides a way to still obtain the result for all variables.

      Notes:
      • If the store option is activated, you can specify the result generation interval when storing simulation results by changing the value of the flag Advanced.FMI.FMUStoreResultInterval. The default value of the flag is 0.001 (seconds).
      • Simultaneous use of result storing and source code inclusion (see below) is not supported.

      By default, this parameter is set to false.

    3. Set modelName to the wanted FMU model name.

      This can be used to give the FMU a shorter name.

      Warning: The FMU file name must only contain letters, digits, and underscores. It must not begin with a digit.

      By default, the string is empty, giving the FMU the model name, including the path (e. g. Modelica_Mechanics_Rotational_Examples_CoupledClutches.fmu).

    4. Set fmiVersion depending on what FMI version you want to use, for example fmiVersion=2 if you want to use FMI version 2.0. The default value is 1.
    5. Specify fmiType depending on the type of FMU that is to be exported:

      • fmiType="me" if the FMU is to be exported as model exchange.
      • fmiType="cs" if the FMU is to be exported as Co-simulation.
      • fmiType="all" if the FMU is to be exported as both model exchange and Co-simulation.
      • fmiType="csSolver" if the FMU is to be exported using the current Dymola solver and tolerance.

      This parameter primarily affects modelDescription.xml. For the first three alternatives, binary code and source code always contain both model exchange and Co-simulation. For the last alternative, the binary code only contains Co-simulation.

      By default, this parameter is fmiType="all".

    6. Optional: Specify includeSource=true if the source code is to be included in the FMU.

      Notes:
      • Simultaneous use of source code inclusion and result storing (see above) is not supported.
      • Source code generation is not supported for Co-simulation using Dymola solvers.

      By default, this parameter is specified to false; no source code is included.

    7. Optional: You can select to include an image in the exported FMU by specifying includeImage the following way:

      • includeImage=0 if no image is to be included. This is the default.
      • includeImage=1 if an image of the icon of the model is to be included.
      • includeImage=2 if an image of the diagram layer of the model is to be included.

      If you have selected to include an image, the image is stored in the FMU resources with the name model.png.
      Note: This means that you can yourself replace this image with another image with this name.
    8. To specify in detail what variables are to be exposed, you can use the parameter includeVariables.

      You have two options:

      • You can leave this parameter as an empty array. Then all variables that pass the model description filters are exposed. You can control the filtering by three flags, see Step 11 in the subtask above.

        The default value of includeVariables is an empty array.

      • To specify in detail what variables to expose, you can enter these variables in the parameter includeVariables.

        In that case, the model description filters are ignored.

  3. Execute the script.

    Note: For more information about script execution, see Step 1.

    When the script is executed:
    • A progress bar appears.
    • The Message Reporting window appears to let you know the export result.
    • If the export is successful, the .fmu file containing .dll resources is created in the default directory (cd). The output string FMUname contains the FMI model identifier on success. On failure, the string is empty.