Difference between revisions of "Scilab/C4/User-defined-variables-in-Xcos/English"

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Learning Objectives

In this tutorial, we will learn how to:

• Pass variables from Scilab Console to Xcos.

• Pass variables from context menu to Xcos.

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System Requirements

To record this tutorial, I am using

• Windows 10 OS

• Scilab 6.1.0

The process demonstrated in this

tutorial is identical in Linux OS also

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Prerequisite

https://www.spoken-tutorial.org

Before practising this tutorial, a learner should have :

• Basic knowledge of Scilab and Xcos.

If not, then go through the Scilab spoken tutorials on this website.

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Variables

There are two ways to define variables in Xcos:

• Defining variables from the Scilab Console.

• Defining variables from the context menu.

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Simulation - Blocks used

For this we used the below blocks

• RAMP

• CLOCK underscore c and

• CSCOPE

Open Scilab.

Type in ‘xcos’ in the Scilab console and press enter.

Two windows will open :

• Palette browser and the

• Untitled-Xcos window.

Show Xcos window

Sources palette>>RAMP block

To create the simulation we will have to import the necessary blocks.

• In the Palette browser-Xcos window, click on Sources palette.

• In the right panel, select the RAMP block.

• Now, drag and drop this block in the Untitled-Xcos window.

• Go to the Palette browser-Xcos window.

• Click on the sinks palette.

• In the right panel, scroll down and select the CSCOPE block.

• Drag and drop it next to the RAMP block in the Untitled-Xcos window

• Again go to the event handling palette, select the CLOCK underscore c block.

• Then drag and drop it above the CSCOPE block in the untitled -Xcos window

Next we will interconnect all the blocks.

• Connect black output port of RAMP to black input port of CSCOPE.

• Connect the red output port of CLOCK underscore c to the red input port of CSCOPE.

• Our simulation is ready.

• Then right click on the RAMP block and select the block parameters.

• Here we set the slope parameter to ‘a’ and click OK .

• It shows an error as ‘a’ is not defined.

• This is correct because we never defined the variable ‘a’ before.

Our first way to define a variable is using the Scilab console.

For this, go to the Scilab console .

Type ‘a=1’ and press enter

Now come back to the Untitled-Xcos window .

• Right click on the RAMP block and select the block parameter option in the menu.

• Again we set the slope parameter to ‘a’ and click ok.

To start the simulation, go to the toolbar of the Untitled-Xcos window.

Then click on the Start button that is of the shape of the play button.

We will see a warning message saying that there is no continuous time state.

This can be ignored in this example. So click on OK.

Next we will see how to define variables

using the context menu in the Xcos toolbar.

First we will have to clear the previous value of a. For this :

• Go to the scilab console window

• Type in ‘clear a’ in the console and press enter .

• Now type ‘a’ and press Enter

• We can see that the console shows ‘a’ as undefined.

Show Xcos window and context menu

a=1

• Next, in the menu bar of the Untitled-Xcos window, click on Simulation.

• In the drop down menu select the set context option.

• set context popup window appears.

• Type a=1 in the window and click ok.

Now we execute the simulation again:

• Go to the toolbar and click start.

• Click ok in the warning window.

• Then switch to the graphic window

• We can see that the slope of output RAMP changed to ‘a’.

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Advantages of Context menu

• Using the set context menu we can include the variables in the simulation itself.

• We need not carry an additional sci file just to initialize the variable.

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Summary

This brings us to the end of this tutorial. Let us summarise.

In this tutorial, we have learnt to:

• Pass variables from Scilab Console to Xcos.

• Pass variables from context menu to Xcos.

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Assignment

As an assignment, please do the following

• Change the value of variable ‘a’ to 5 using the Console window and context menu.

• Check the output in the graphic window.

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About Spoken Tutorial Project

The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

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Spoken Tutorial Workshops

The Spoken Tutorial Project Team conducts workshops and gives certificates.

For more details, please write to us

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Answers for THIS Spoken Tutorial

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Textbook Companion project

The FOSSEE team coordinates the Textbook Companion project.

We give Certificates and Honorarium to the contributors.

For more details, please visit this site..

The FOSSEE team coordinates the Lab Migration project.

For more details, please visit this site.

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Acknowledgement

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Thank you

This is Iswariya Sasikumar, a FOSSEE intern 2021, IIT Bombay signing off.

Thanks for joining.