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Graphical user interface limitations🔗

Workspace panel🔗

  • It is not possible to import a global library using the web browser. Users can manually install global libraries. Valid for Desktop installation.
  • The Import functionality is intended for full libraries or standalone models. It is not possible to import a class from within a library. A workaround is to export the class or duplicate it to the workspace.


  • Units can only be set globally in Settings and not for individual variables.


  • The counter showing the number of iteration variables and residuals is not supported for experiments.


  • It is not possible to explicitly set the exact intervals of the plot axis.
  • It is not possible to zoom along a dimension in plots. It's only possible to shift-mouse scrolling the axis but not in the plot (as for box-zooming).
  • It is not possible to use custom functions for the steady state plotting in this version.

Documentation editor🔗

  • It is not possible to upload an image directly from the editor. This can be done by uploading to the Resource folder first. 
  • Not all styling from a copied styled text (e.g. from MS Word) will be kept when pasted into the Documention editor

Conversion scripts🔗

  • When updating a workspace, the update will fail if a package name starts with the same name as a library it depends on (e.g. ModelicaTest, which depends on Modelica).
  • Conversion scripts do not support 'convertElement' for modifiers of an instantiated component’s submodel.
  • Views are not updated when changing variable names manually or when updating libraries using conversion scripts. 
  • Favorites are not updated when changing variable names manually or when updating libraries using conversion scripts.

Modelica limitations🔗

This section summarizes the parts of the Modelica specification that Modelon Impact does not fully support. Note that the below limitations can effectively be worked around by directly editing the Modelica source code in the code editor.

  • It is not possible to modify parameters for record arrays.
  • Modelica.Clocked in MSL 4.0 is not supported.
  • The graphical user interface (GUI) of Modelon Impact does not support all UI interpretations proposed in the Modelica specification, such as regarding protected or final declared statements or certain line styles.

User interface limitations🔗

These limitations address functionality that is not accessible through the standard Modelon Impact user interface.


While these are not yet available in the user interface, this does not affect Modelon Impact's ability to compile and simulate models making use of these features.

For limitations relating to the compilation and simulation of models, see Compiler limitations.

Connectors and connections🔗

  • Text primitives on connection lines are not shown and cannot be added.

Icon and diagram graphics🔗

  • The preserveAspectRatio annotation is not considered when resizing a component. Note, that the aspect ratio can be preserved using the corner point.
  • Some fill patterns for graphical objects will be drawn as solid colors: Horizontal, Vertical, Cross, Forward, Backward, CrossDiag.
  • Border patterns are not supported: Raised, Sunken, Engraved.
  • Support for arrowheads and line patterns for Line primitives is partial.
  • The textStyle, fontName and fontSize attributes are not supported for Text primitives.
  • The visible annotation for graphical primitives is not supported in experiment mode.
  • Modelon vendor-specific DialogExtensions annotations hide, hideInEditingState and hideInNonEditingState are not supported in experiment mode.
  • Scatter plots can only show variables from the active result. 
  • Scatter plots and X-Y plots cannot be pinned.
  • It is not possible to pan (by dragging on the axes) in scatter plots.
  • Impact does not support bitmap graphics in Icon or Diagram annotations that are stored binary in Modelica code. Bitmaps (PNG, JPG, BMP) must be available as a file in the Modelica Resources folder and can then be linked in the graphic annotations.


  • It is not possible to create a short-class declaration. e.g. “replaceable package Medium=WaterIF07”.


  • The displayUnit attribute is not supported. A global setting for converting units is provided instead.
  • It is not possible to modify parameters in record arrays.
  • It is not possible to modify parameters in nested component arrays.


Code editor can be used to work on lots of the above GUI-related limitations.

Desktop installation🔗

  • The application settings are saved in the browser and will persist into newly installed versions. To revert to the default settings the browser cookies should be cleared. Valid for Desktop installation.
  • Chrome is expected to be installed in the standard location (C:\Program Files (x86)\Google\Chrome\Application). Go to troubleshooting to change the default browser and its installation location. Valid for Desktop installation.

Optimica Compiler Toolkit (OCT)🔗

Detailed OCT limitations are listed within the user guide.

The following limitations apply to the language elements that can be used:

  • Support for partial function calls is limited.
  • For Modelica 3.4, the language elements described in the specification in Chapter 16 - Synchronous Language Elements and Chapter 17 - State Machines, are not supported.
  • The built-in function terminal() is not supported.
  • The annotations version, arrayLayout, obsolete and unassignedMessage are not supported.
  • Partial derivatives are not supported.
  • The inverse annotation does not support using references with array indices or dotted references as arguments to the inverse function.


  • Modelon Impact is yet not designed to run on tablets or mobile devices.