View source for Scilab/C4/User-defined-variables-in-Xcos/English

'''Title of script: User-defined variables in Xcos'''

'''Author:Rupak Rokade and Anandajith TS'''

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! '''Visual Cue'''
! '''Narration'''
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'''Title Slide'''
| Hello and welcome to the Spoken Tutorial on “ '''User-defined Variables in Xcos'''”
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'''Learning Objectives'''
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In this tutorial, we will learn how to:

<ul>
<li><blockquote><p>Pass '''variables''' from '''Scilab Console''' to '''Xcos.'''</p></blockquote></li>
<li><blockquote><p>Pass '''variables''' from '''context menu''' to '''Xcos.'''</p></blockquote></li></ul>
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'''System Requirements'''
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To record this tutorial, I am using

<ul>
<li><blockquote><p>'''Windows 10 OS'''</p></blockquote></li>
<li><blockquote><p>'''Scilab 6.1.0'''</p></blockquote></li></ul>

The process demonstrated in this

tutorial is identical in '''Linux''' OS also
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'''Prerequisite'''

https://www.spoken-tutorial.org
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Before practising this tutorial, a learner should have :

<ul>
<li><blockquote><p>Basic knowledge of '''Scilab and Xcos.'''</p></blockquote></li></ul>

If not, then go through the '''Scilab''' spoken tutorials on this website.
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'''Variables'''
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There are two ways to define '''variables''' in '''Xcos''':

<ul>
<li><blockquote><p>Defining variables from the '''Scilab Console.'''</p></blockquote></li>
<li><blockquote><p>Defining variables from the context '''menu.'''</p></blockquote></li></ul>
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| First we will create a simple '''simulation.'''
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Simulation - Blocks used
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For this we used the below blocks

<ul>
<li><blockquote><p>'''RAMP'''</p></blockquote></li>
<li><blockquote><p>'''CLOCK underscore c''' and</p></blockquote></li>
<li><blockquote><p>'''CSCOPE'''</p></blockquote></li></ul>
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| Show '''Scilab workspace window'''
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Open '''Scilab.'''

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

Two windows will open :

<ul>
<li><blockquote><p>'''Palette browser''' and the</p></blockquote></li>
<li><blockquote><p>'''Untitled-Xcos window.'''</p></blockquote></li></ul>
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Show '''Xcos window'''

'''Sources palette&gt;&gt;RAMP block'''
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To create the '''simulation''' we will have to import the necessary '''blocks.'''

<ul>
<li><blockquote><p>In the '''Palette browser-Xcos''' window, click on '''Sources''' palette.</p></blockquote></li>
<li><blockquote><p>In the right panel, select the '''RAMP''' block.</p></blockquote></li>
<li><blockquote><p>Now, drag and drop this block in the '''Untitled-Xcos''' window.</p></blockquote></li></ul>
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| '''Sinks palette&gt;&gt;CSCOPE block'''
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<ul>
<li><blockquote><p>Go to the '''Palette browser-Xcos window'''.</p></blockquote></li>
<li><blockquote><p>Click on the '''sinks palette'''.</p></blockquote></li>
<li><blockquote><p>In the right panel, scroll down and select the '''CSCOPE''' block.</p></blockquote></li>
<li><blockquote><p>Drag and drop it next to the '''RAMP''' block in the '''Untitled-Xcos window'''</p></blockquote></li></ul>
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| '''Event handling&gt;&gt;Clock_c block'''
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<ul>
<li><blockquote><p>Again go to the '''event handling palette''', select the '''CLOCK underscore c block.'''</p></blockquote></li>
<li><blockquote><p>Then drag and drop it above the '''CSCOPE block''' in the '''untitled -Xcos window'''</p></blockquote></li></ul>
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| Show '''Xcos window'''
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Next we will interconnect all the '''blocks.'''

<ul>
<li><blockquote><p>Connect black '''output''' port of '''RAMP''' to black '''input''' port of '''CSCOPE.'''</p></blockquote></li>
<li><blockquote><p>Connect the red '''output''' port of '''CLOCK underscore c''' to the red '''input''' port of '''CSCOPE'''.</p></blockquote></li>
<li><blockquote><p>Our simulation is ready.</p></blockquote></li></ul>
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| Show '''Xcos window'''
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<ul>
<li><blockquote><p>Then right click on the RAMP '''block''' and select the block '''parameters.'''</p></blockquote></li>
<li><blockquote><p>Here we set the '''slope parameter''' to '''‘a’''' and click '''OK''' .</p></blockquote></li>
<li><blockquote><p>It shows an error as '''‘a’''' is not defined.</p></blockquote></li>
<li><blockquote><p>This is correct because we never defined the '''variable ‘a’''' before.</p></blockquote></li></ul>
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| '''Show Scilab workspace window'''
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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'''
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| '''Show Xcos window'''
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Now come back to the '''Untitled-Xcos window''' .

<ul>
<li><blockquote><p>Right click on the '''RAMP block''' and select the '''block parameter''' option in the menu.</p></blockquote></li>
<li><blockquote><p>Again we set the '''slope parameter''' to '''‘a’''' and click '''ok.'''</p></blockquote></li></ul>
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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.
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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.'''
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| '''Show graphic window'''
| Now, we can see that the '''slope''' of the output '''RAMP signal''' changes to '''a''' in the graphic window.
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Next we will see how to define variables

using the '''context menu''' in the '''Xcos toolbar.'''
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| Show '''workspace window'''
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<blockquote>First we will have to clear the previous value of '''a'''. For this :
</blockquote>
<ul>
<li><blockquote><p>Go to the '''scilab console window'''</p></blockquote></li>
<li><blockquote><p>Type in '''‘clear a’''' in the '''console''' and press '''enter''' .</p></blockquote></li>
<li><blockquote><p>Now type '''‘a’''' and press Enter</p></blockquote></li>
<li><blockquote><p>We can see that the '''console''' shows ‘'''a’''' as undefined.</p></blockquote></li></ul>
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Show '''Xcos window''' and '''context menu'''

'''a=1'''
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<ul>
<li><blockquote><p>Next, in the menu bar of the '''Untitled-Xcos window,''' click on '''Simulation'''.</p></blockquote></li>
<li><blockquote><p>In the drop down menu select the '''set context''' option.</p></blockquote></li>
<li><blockquote><p>'''set context''' popup window appears.</p></blockquote></li>
<li><blockquote><p>Type a=1 in the window and click ok.</p></blockquote></li></ul>
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| Show '''Xcos window'''
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Now we execute the simulation again''':'''

<ul>
<li><blockquote><p>Go to the '''toolbar''' and click '''start.'''</p></blockquote></li>
<li><blockquote><p>Click '''ok''' in the warning window.</p></blockquote></li>
<li><blockquote><p>Then switch to the graphic window</p></blockquote></li>
<li><blockquote><p>We can see that the '''slope''' of '''output RAMP''' changed to '''‘a’'''.</p></blockquote></li></ul>
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'''Advantages of Context menu'''
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<ul>
<li><blockquote><p>Using the '''set context menu''' we can include the variables in the simulation itself.</p></blockquote></li>
<li><blockquote><p>We need not carry an additional '''sci file''' just to initialize the variable.</p></blockquote></li></ul>
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'''Summary'''
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This brings us to the end of this tutorial. Let us summarise.

In this tutorial, we have learnt to:

<ul>
<li><blockquote><p>Pass variables from '''Scilab''' '''Console''' to '''Xcos.'''</p></blockquote></li>
<li><blockquote><p>Pass variables from '''context menu''' to '''Xcos.'''</p></blockquote></li></ul>
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'''Assignment'''
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As an assignment, please do the following

<ul>
<li><blockquote><p>Change the value of variable ‘a’ to 5 using the Console window and context menu.</p></blockquote></li>
<li><blockquote><p>Check the output in the graphic window.</p></blockquote></li></ul>
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'''About Spoken Tutorial Project'''
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Please download and watch it.
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'''Answers for THIS Spoken Tutorial'''
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'''Acknowledgement'''
| Spoken Tutorial and FOSSEE projects are funded by MoE, Government of India.
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'''Thank you'''
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This is Iswariya Sasikumar from FOSSEE intern 2021, IIT Bombay signing off.

Thanks for joining.
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