Difference between revisions of "Scilab/C4/Loading-and-saving-data-in-Xcos/English"

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Learning Objectives

In this tutorial, we will learn how to:

• Save Xcos simulation data values to the workspace.

• Read and write data in Xcos simulation using a C binary file

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System Requirements

To record this tutorial, I am using

• Ubuntu 18.04 OS and

• Scilab 6.1.0 version

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Pre-requisites

To follow this tutorial, you should have

• Basic knowledge of Scilab and Xcos.

• If not, for relevant tutorials please visit this website.

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Code Files

• The files used in this tutorial are provided in the Code files link.

• Please download and extract the files.

• Make a copy and then use them while practising.

I have already opened the Xcos windows.

We can see two windows named Untitled Xcos and the Palette browser are opened.

On the Untitled Xcos window,

Cursor on Toolbar >> Click on Open file option >> Click on SaveData.xcos >> Click on OK.

Go to the Untitled Xcos window.

Click on the Open File icon on the Toolbar.

A window will appear.

Go to the Downloads folder and select the file SaveData.xcos.

Then click on the OK button.

Let me adjust the window.

I have already created this file for demonstration.

On the SaveData.xcos window,

cursor on the SaveData.xcos window.

On the SaveData.xcos window,

Hover cursor on RAMP block.

On the SaveData.xcos window,

Hover cursor on CSCOPE block.

And the CSCOPE block to plot it.

Let us see how to record the generated Ramp signal.

On the SaveData.xcos window,

cursor on the SaveData.xcos window

On palette browser,

click on Sinks >> scroll down >> click on TOWS_c.

Go to the palette browser window.

Click on the Sinks palette.

In the right panel, select the TOWS_c block. This is the To Workspace block.

On the editing window,

Double click on the TOWS_c block.

On the Scilab Multiple Values Request Window of TOWS_c block,

Double click on the Size of Buffer. Text field to highlight it.

The size of buffer is by default set to 128.

This means that 128 values will be saved in the block .

If any more values are passed, the block will overwrite the previous values.

On the Scilab Multiple Values Request Window of TOWS_c block,

Double click on the Variable Name text field to highlight it.

The Variable Name is the name of the variable to which the values are saved.

By default it is set to A.

On the Scilab Multiple Values Request Window of TOWS_c block,

Double click on the Inherit Text field to highlight it.

Click on the OK button at the bottom.

Inherit is used to decide whether to take the event input or not.

By default Inherit is set to 0 which means it has to take event input.

Click on the OK button to close this window.

On SaveData.xcos Window,

Connect as per narration.

Let us make the connections.

Select the black input port of the TOWS_c block.

Connect it to the line joining the RAMP and the CSCOPE block.

On SaveData.xcos Window,

Connect as per narration.

Next, Select the red input port of the TOWS_c block.

Connect it to the line joining the CLOCK_c and the CSCOPE block.

Our file is ready for simulation.

On the SaveData.xcos window,

Click on Start button on the toolbar >> click on OK button on the Warning message.

Let us run this simulation by clicking on the Start Button on the toolbar.

An Warning message will appear.

Ignore the message and click on the OK button.

On the Graphic window,

Hover cursor on the graph.

Close the Graphic window.

We can see a straight line with slope 2.

Let’s close the graphic window.

Now let us look at the values.

Switch to the workspace.

On the workspace,

Type A >> press Enter.

Let us execute the variable A.

Type A on the workspace and press Enter.

On the workspace window,

Highlight variable A.

Highlight values.

Highlight time.

A is a special variable.

We can either extract values from A or we can extract times from A.

Let us look at the values.

On the workspace window,

Type A.values >> Press Enter.

Type A.values on the workspace.

Press Enter.

On the workspace,

Scroll up to show all the values and Highlight them.

On the workspace,

hover cursor on a new line on the workspace.

On the palette browser,

Click on Sinkss >> Click on WRITEC_f block.

To save these values, we will use the WRITEC_f block.

Go to the palette browser window.

Click on the Sinks palette.

Click on the WRITEC_f block in the right panel.

This is the Write to C binary file block.

On the SaveData.xcos window,

Double click on WRITEC_f block.

On the Scilab Multiple Values Request Window of WRITEC_f block,

Double click on the Input Size Text field to highlight it.

On the Scilab Multiple Values Request Window of WRITEC_f block,

Double click on the Output File Name Text field to highlight it >> Change it to ‘data’

Output File is the name of our output file.

I will name the output file as ‘ data ‘.

If no file path is entered, the file will be saved in the Current working directory.

On the Scilab Multiple Values Request Window of WRITEC_f block,

Double click on the Output Format Text field to highlight it >> Change it to ‘ d ’

Output Format is the format of the output file.

By default it is ‘ c ‘. That is, by default, values are saved as integers.

But, I want to save the values as double. So, I will change it to ‘d’.

On the Scilab Multiple Values Request Window of WRITEC_f block,

Double click on the Buffer Size Text field to highlight it.

On SaveData.xcos Window,

Connect as per narration.

Let us make the connections.

Select the black input port of the WRITEC_f block.

Connect it to the line joining the RAMP and the CSCOPE block.

On SaveData.xcos Window,

Connect as per narration.

Next, Select the red input port of the WRITEC_f block.

Connect it to the line joining the CLOCK_c and the CSCOPE block.

Our file is ready for simulation.

On the SaveData.xcos window,

Click on Start button on the toolbar >> click on OK button on the Warning message.

Let's run the simulation again by clicking on the Start Button on the toolbar.

A Warning message will appear. Ignore the message and click on the OK button.

On the Graphic window,

Hover cursor on the graph.

Close the Graphic window.

We can see the graph.

Let’s close the graphic window.

On file manager window,

Click on the data file once.

We can see a file named ‘ data ‘ .

Since it is a binary encoded file we cannot simply read it.

We would need a special block to read this file.

On the SaveData.xcos window,

Cursor on Toolbar >> Click on Open file option >> Click on LoadData.xcos >> Click on OK

Let us open the file LoadData.xcos

Click on the Open File icon on the Toolbar.

A window will appear.

Go to Downloads Folder and select the file LoadData.xcos.

Then click on the OK button.

We will use this file to read our data file.

On the palette browser,

Click on Sources >> Click on READC_f block.

We will use the READC_f block to read our values.

Go to the palette browser window.

Click on the Sources palette.

Click on READC_f Block in the right panel.

This is the Read from C Binary block.

On the LoadData.xcos window,

Double click on READC_f block..

On the Scilab Multiple Values Request Window of READC_f block,

Double click on the Input File Name Text field to highlight it. >> Change it to data

Input file name is the name and the path of your data file.

Since my data file was named data I will change it to data.

On the Scilab Multiple Values Request Window of READC_f block,

Double click on the Input Format Text field to highlight it >> Change it to d.

Input format is the format of the data file.

Since the format for my data file is double , I will change it to d.

On the Scilab Multiple Values Request Window of READC_f block,

Double click on the Buffer Size Text field to highlight it.

Click the OK button .

This is the buffer size.

Let’s close this window by clicking on the OK button.

On LoadData.xcos Window,

Connect as per narration.

Let us make the connections.

Select the black output port of the READC_f block.

Connect it to the black input port of the CSCOPE block.

On LoadData.xcos Window,

Connect as per narration.

Lastly, Select the red input port of the READC_f block.

Connect it to the line joining the CLOCK_C & the CSCOPE block.

On the LoadData.xcos window,

Click on Start button on the toolbar

On the Graphic Window,

Hover Cursor on the Graph.

We have a similar graph to the one we had earlier without using the RAMP block.

This is because we have loaded the values from the data file.

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Summary

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

In this tutorial, we have learnt to:

• Save Xcos simulation data values to the workspace.

• Read and write data in Xcos Simulation using a C binary file

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Assignment

As an assignment,

Create two Xcos simulation files:

• Use the first for plotting a straight line with slope 3.

• Push the values to the workspace and save them as a binary encoded file.

• Create another Xcos simulation to plot a new graph of a straight line with slope 3.

• Use only the saved data values.

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

Please download and watch it

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Answers for THIS Spoken Tutorial

Please post your general and technical queries on Scilab in this forum.

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Textbook Companion project.

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We give Certificates and Honorarium to the contributors.

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This is Utkarsh Anand, FOSSEE intern 2021, IIT Bombay signing off.

Thanks for joining.