Classes

Classes and Libraries

Introduction

This tutorial will teach the process of constructing classes, as a method to manage sub-models.  This document augments the chapters in the Basic Technology document covering Classes and Library.  It assumes that the following directory structure has been set up in <VS>/VS_AR

In other words, the following paths are used in this document:

The following top-down design steps are followed in this exercise:

Short Excercise on Creating Classes

Step 1: Create Top-Level Block Diagram

• Open a new block diagram by selecting menu File->New->Block Diagram Editor
• Instantiate a model parameter by dragging ModelSetup->Parameter= onto the block diagram
• Right-click on this parameter and select menu Customize Name
• Type “TStop” as the name of the parameter and hit the “Commit” button
• Double-click on this parameter and specify a value of 10.0 (feel free to change this value as you experiment with this model)
• Instantiate a “Digital” block from the Library pane ModelSetup->Digital
• Double-click the “Digital” block and type in “TStop” for the block parameter “stopTime”
• Instantiate a “Hierarchical_Block” from the Library pane ModelSetup -> Hierarchical_Block

Step 2: Specify Ports for Hierarchical Block

• Right-click on the Hierarchical Block and select menu item Customize-> Ports
• Click on the “Add” button and add an output port as shown below

Step 3: Specify and Verify the Functional Behavior of the Hierarchical Block

• Right-click on the Hierarchical Block and select menu Open Block
• Instantiate a model parameter by dragging ModelSetup->Parameter= onto the block diagram
• Right-click on this parameter and select menu Customize Name
• Type “TStop” as the name of the parameter and hit the “Commit” button
• Double-click on this parameter and specify a value of 10.0
• Instantiate a “Digital” block from the Library pane ModelSetup->Digital
• Double-click the “Digital” block and type in “TStop” for the block parameter “stopTime”
• Instantiate an instances of the “Traffic” block using Traffic->Traffic
• Instantiate an instances of the “Processing” block using Full Library -> Defining_Flow->Processing
• For the “Processing” block, type the following in block parameter “Expression_List”
• input.Time_Generated = TNow
• Connect the blocks/ports as in the following figure
• In the top-level diagram, type in “TStop” for hierarchical block parameter “TStop”
• In the top-level diagram, verify that the hierarchical block is working properly.

Step 4: Create a Class using the Hierarchical Block

• In the top-level diagram, right-click on the Hierarchical_Block and select menu Convert to Class
• Right-click on the Hierarchical_Block and select menu Open Block
• Inside the hierarchical block, click on menu item File -> Save As
• Select “Save submodel only:” (see figure below)
• Save the block as “Source.xml” in location <VS>/VS_AR/User_Libraries/Components

Step 5: Instantiate a Class from the VS GUI

• One way of instantiating a class is to use the VS GUI
• For example, open a new block diagram by selecting menu File->New->Block Diagram Editor
• Select menu Graph -> Instantiate Entity
• In “Class name:”, put location User_Libraries.Components.Source as below

Step 6: Create a New Library

• A better way to use a class is to have it be an item in a Library.  The user can create a library under the User_Library folder.
• It is best to create the library within the confines of the UserLibrary.
• To create the library, first right-click on User_Library in the Folder and select ‘Open for Editing’
• Next select Graph->InstantiateEntity and edit ClassName: VisualSim.moml.EntityLibrary.  This will create a new folder. Make sure the Library name does not end in a numeral.
• Convert this library to a Class by Right-click on the block and Convert to class.
• Open this Hierarchical Block and Save As with sub-model selected.

Step 7: Populating the New Library

• Open the library file by doing a File->Open and selecting this file for editing.  
• Drag-n-Drop items from the UserLibrary or other directories into this window. You cna also include other classes by Graph->InstantiateEntity.
• Note: Make sure there is a Digital simulator in this library folder.  This is needed or you will receive an error each time you open VisualSim.

Step 8: Import this New Library into the User_Library

• Right-click on User_Library and select ‘Open for Editing’
• Using Graph->InstantiateEntity and select the library created above
• Save

Step 9: View this New Library in the User_Library

• Restart VisualSim
• The new library will be visible in the User_Library