Difference between revisions of "OpenModelica/C3/Modelica-Packages/English"

Title Slide

Learning Objectives

• How to create a package of classes in Modelica.

• How to reference classes in a package.

• How to import a package and

• How to use Modelica Library.

System Requirements

• OpenModelica 1.9.2 and
• Ubuntu Operating System version 14.04 and
• gedit.

Windows users may use Notepad or any other text editor instead of gedit.

Prerequisites

• Knowledge of class and type definition in Modelica.
• Prerequisite tutorials are mentioned on our website.

Please go through them.

Package

It is a collection of classes.

It can be stored as a single file or a directory.

We will first learn about single file storage.

Single file storage

It is not recommended as it may get lengthy in a few cases.

Click on Modeling button at bottom right

You may see that there is a file and a folder bearing the name spokenTutorialExamples.

Please download both of them.

Press Ctrl + O.

Go to the appropriate location on your system and select

• spokenTutorialExamples.mo,

• bouncingBallWithUserTypes.mo and

• bouncingBallWithImport.

You may also open each of them individually.

Note that I have not selected spokenTutorialExamples folder.

We shall discuss more about it when we look at directory storage.

Click on Open.

You may see that spokenTutorialExamples package is now seen in Libraries Browser.

package spokenTutorialExamples

First line defines the name of a package.

Evidently, name of this package is spokenTutorialExamples.

class freeFall

model bouncingBall

model bouncingBallWithUserTypes

//

• freefall class
• bouncingBall model and
• bouncingBallWithUserTypes models.

Now, let us learn how to view individual classes in a package.

This displays the names of classes present in this package.

freeFall class has now opened.

Individual classes of a package may be simulated.

But the package itself can not be simulated.

Do a right-click and select unload.

Select Yes.

This is done so as to avoid conflict when demonstrating directory storage.

Directory storage

Name of directory is same as that of the package.

A file named package.mo is to be included in the directory and

Each class starts with a within statement.

Note that this folder represents the same package as that we have already discussed.

Go to the location where you saved the downloaded files on your system.

Notice that the folder has following files:

• package.mo,

• freeFall.mo,

• bouncingBallWithUserTypes and

• bouncingBall.

We shall understand more about directory storage using both OMEdit and gedit.

Without this file, the folder doesn’t represent a Modelica package.

Ctrl+O

spokenTutorialExamples → package.mo

Press Ctrl + O.

Navigate to the spokenTutorialExamples folder that you have downloaded.

Select package.mo from this folder and click on Open.

Double-click on spokenTutorialExamples icon.

Scroll down

You may use notepad or any other text editor if you are using windows.

Double-click on bouncingBall.mo, bouncingBallWithUserTypes ,freeFall, package.mo.

Now all the files are open in gedit.

Let us take a look at package.mo first.

Note that the name of folder was spokenTutorialExamples as well.

within spokenTutorialExamples;

Rest of this file has information specific to freeFall class.

But, we didn’t observe within statement when we opened the package in OMEdit.

This indicates that within statement helps OMEdit recognize the file structure.

Hence, it is omitted by OMEdit while displaying the package.

Modelica Library

Modelica Library is an open-source package.

OMEdit automatically loads it for every session.

It can be seen in Libraries Browser.

It has classes from mechanical, electrical and thermal domains.

Classes of this library can be referenced and used.

Note that Modelica Library has packages named Blocks , Complex Blocks etc.

You may note that a package may further contain packages as well as it evident here.

Expand it.

We shall see how to use these type definitions using bouncingBallWithImport class.

Compress SIunits.

We have learnt about this model in the prerequisite tutorials.

type Length = Real(unit = “m”);

type Velocity = Real(unit = “m/s”);

We can instead use the type definition in SIunits instead of defining them explicitly in every model.

We shall see how to do that using bouncingBallWithImport model.

Modelica.SIunits refers to SIunits package which belongs to Modelica library.

Now let me Simulate this model.

Click on Simulate button in the toolbar.

Close the pop up window.

Select h in the Variables Browser.

let me de-select h.

Delete the result.

Switch to Modeling perspective.

This can be simplified using import statement.

Now, we shall type a few statements that show the use of import.

The statements to be typed are provided in a text file named import-statements.txt.

Go to the location where you saved it on your system.

Double-click on import-statements.txt.

Windows users may use notepad to open this file.

Copy the statements:

import Modelica.SIunits.Length;

import Modelica.SIunits.Velocity;

Length h;

Velocity v;

Copy all the statements using Ctrl+C or by doing right click.

import Modelica.SIunits.Length;

import Modelica.SIunits.Velocity;

Length h;

Velocity v;

//

Paste all the statements at the beginning of the model.

Modelica.SIunits.Velocity //

Delete the extra spaces.

Save this model by pressing Ctrl + S.

Now the model is complete and ready for simulation.

Close the pop up window.

Note that the plot is same as in previous case.

De-select h and delete the result.

Switch to Modeling perspective.

import Modelica.SIunits.Length;

import Modelica.SIunits.Velocity;

//

Using the import statements Modelica looks up for Length and Velocity type definitions using the path mentioned here.

This saves the trouble of referring to the package every time.

A detailed discussion of lookup rules is beyond the scope of this tutorial.

import Modelica.SIunits.Length;

import Modelica.SIunits.Velocity;

//

Delete the two statements.

import Modelica.SIunits.*;

Save this model by pressing Ctrl + S

This way, any class from SIunits may be accessed without explicitly mentioning it.

Click on simulate button.

Close the pop up window.

You may notice the similarity of plot once again.

De-select h and delete the result.

Assignment

Declare variable h and v of freeFall class as Length and Velocity types respectively.

These type definitions can be found in SIunits package of Modelica library.

About the Spoken Tutorial project

http://spoken-tutorial.org /What\_is\_a\_Spoken\_Tutorial

It summarises the Spoken Tutorial project.

If you have questions in this Spoken Tutorial, please visit the website shown.

Textbook Companion Project

We give honorarium to contributors.

Please visit our website.

Lab Migration Project

Please visit the following website.

Acknowledgements

Thanks

Good bye.