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Visual Cue Narration
Slide Number 1

Title Slide

Welcome to the spoken tutorial on Annotations.

Learning Objectives

In this tutorial, we are going to learn:
  • How to specify an annotation and
  • How to define a record

System Requirements

To record this tutorial, I am using:
  • OpenModelica 1.9.2
  • You may use any of the following operating systems to practice this tutorial.


To understand and practice this tutorial, you need knowledge of class definition in Modelica.

Please watch the prerequisite tutorials available on our website.



Annotations can appear at multiple locations in a class.

They may be used to:

  • change simulation settings
  • to add supporting documentation and
  • to add icon and diagram views to a class


In the previous tutorials, we used SimulationSetup button in the toolbar to vary simulation settings.

experiment is a model annotation that may be used to vary the following:

  • Start Time
  • Stop Time
  • Tolerance and
  • Interval

Discussion of Tolerance and Interval are beyond the scope of this tutorial series.


Syntax for experiment

Shown here is an example demonstrating the syntax of experiment annotation.
Now, we shall understand experiment annotation through a class named bouncingBallWithAnnotations.

Let me switch to OMEdit.

Please download all the files available on our website.

Let me open the necessary model files for this tutorial.

Press Ctrl+O.

Go to the appropriate location on your Desktop and select and bouncingBallWithAnnotations.

These files are now open in OMEdit.

We will first look into bouncingBallWithAnnotations.

This model is an extension of the bouncingBall model which we discussed in previous tutorials.

Please watch the prerequisite tutorials for more information on this model.

Double-click on bouncingBallWithAnnotations in Libraries Browser.

Let me shift OMEdit window to the left for better visibility.


// experiment(StartTime=0,StopTime=5) //

Switch to text view if the class opens in either Icon/Diagram View.

The model is now open in Text View.

Let me scroll down a little bit.

Here, we use the experiment annotation to set startTime to 0 and stopTime to 5 units.

experiment annotation serves the same purpose as Simulation Setup toolbox.

Click on Simulation Setup. Click on Simulation Setup button in the toolbar.

You can see the same stopTime and startTime fields here.

We changed the values of these fields using experiment annotation.

Let us simulate the model now.

Click on Simulate icon. Click on Simulate button.
/* Plotting perspective */

Select h in variables browser.

Select h in variables browser.

Note that the simulation interval is 5 units.

This is due to startTime and ‘StopTime fields of experiment annotation.

Now de-select h and delete the result.
Click on Modeling button Click on Modeling button at bottom right.
Now, let us learn more about adding documentation to a model using annotations.
/* bouncingBallWithAnnotations */

Documentation(info = "This is a bouncing ball model with annotations")

The highlighted text appears in Documentation annotation.

Now, let me show an application of Documentation annotation.

Click on Documentation View button Go to the top left of modeling area.

Click on fourth button which is Documentation View.

/* Documentation View */

Highlight // This is a bouncing ball model with annotations //

You can view the text typed in Documentation annotation in the browser.

This functionality allows us to add useful information for larger models which require documentation.

Close Documentation Browser.

Let me go back to the slides.



Record is a specialized class used to define a record data structure.

For example, bank accounts have records with person’s name, age etc.. as fields.

Records can only contain variables.

They may not contain equations.


Example of record

Shown here is an example record named Person.

It has name and age as its fields.

Let me switch to OMEdit to demonstrate record definition.

Let me shift OMEdit window to the right.

We will now use the file named Color.

To open it in Textview, double-click on color icon in Libraries Browser.
record color

Real red;

Real blue;

Real green;

end color;

Highlight each one of them separately.

This record has three variables named red, blue and green.
Hover over Simulate You may see that simulate button doesn’t appear in the toolbar.

This indicates that records are not meant to be simulated.

Now let me go back to slides.

Records in annotations

It is easier to understand annotation elements as records.

For example, experiment annotation can be considered as a record with StartTime, StopTime, Interval and Tolerance as its fields.

Graphical elements can be interpreted similarly.

We will understand more about the interpretation of annotations as records when we discuss icon and diagram views.



As an assignment,

Vary the stop time for simulation of bouncingBallWithAnnotations class from 10 to 20 units.

Use experiment annotation for this purpose.

Simulate the class after this change.

Plot h vs time and notice the change in simulation stop time.

This brings us to the end of this tutorial.

About the Spoken Tutorial project

Watch the video available at the following link.

It summarises spoken tutorial project.


Spoken Tutorial Workshops

We conduct workshops using spoken tutorials .

We give certificates to those who pass an online test.

Please contact us.


Forum to answer questions

If you have questions from this spoken tutorial,

Please visit the following website.


Textbook Companion Project

We coordinate coding of solved examples from popular books.

Please visit the following website.


Lab Migration Project

We help migrate commercial simulator labs to OpenModelica.

We give honorarium and certificates to those who do this.

Please contact us.



Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.


We thank the development team of OpenModelica for their support.

Thank you for joining me in this tutorial.

Contributors and Content Editors

Kaushik Datta, Nancyvarkey