Scilab/C4/User-defined-variables-in-Xcos/English

Title of script: User-defined variables in Xcos

Author:Rupak Rokade and Anandajith TS

Visual Cue	Narration
Show Slide: Title Slide	Hello and welcome to the Spoken Tutorial on “ User-defined Variables in Xcos”
Show Slide: Learning Objectives	In this tutorial, we will learn how to: Pass variables from Scilab Console to Xcos. Pass variables from context menu to Xcos.
Show Slide: 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
Show Slide: 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.
Show Slide: Variables	There are two ways to define variables in Xcos: Defining variables from the Scilab Console. Defining variables from the context menu.
	First we will create a simple simulation.
Show slide: Simulation - Blocks used	For this we used the below blocks RAMP CLOCK underscore c and CSCOPE
Show Scilab workspace window	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.
Sinks palette>>CSCOPE block	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
Event handling>>Clock_c block	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
Show 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.
Show Xcos window	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.
Show Scilab workspace window	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
Show Xcos window	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.
Show graphic window	Now, we can see that the slope of the output RAMP signal changes to a in the graphic window.
	Next we will see how to define variables using the context menu in the Xcos toolbar.
Show workspace window	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.
Show Xcos window	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’.
Show Slide : 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.
Show Slide: 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.
Show slide ; 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.
Show Slide: About Spoken Tutorial Project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
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Show Slide: Acknowledgement	Spoken Tutorial and FOSSEE projects are funded by MoE, Government of India.
Show Slide : Thank you	This is Iswariya Sasikumar, a FOSSEE intern 2021, IIT Bombay signing off. Thanks for joining.

Contributors and Content Editors

Iswariyas