View source for OpenPLC-with-LDmicro/C3/Arithmetic-Instructions/English


{| style="border-spacing:0;"
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| <center>'''Visual Cue'''</center>
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| <center>'''Narration'''</center>

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 1: 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Welcome to the spoken tutorial on '''Arithmetic''' '''Instructions'''

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 2: Learning Objectives

* Arithmetic instructions

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| In this tutorial we’ll learn about 

* Arithmetic instructions
|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 3: System Requirements

* Ubuntu 18.04''' '''operating system
* LDmicro

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| To record this tutorial I am using:

* '''Ubuntu Linux 18.04''' operating system
* '''LDmicro'''

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 4: Pre-requisites

* Working of One Shot instructions
* If not, please refer to the relevant tutorials from [https://spoken-tutorial.org/ Home | spoken-tutorial.org]

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
* To follow this tutorial, you should know the working '''One Shot''' instructions.

* If not, please refer to the relevant tutorials in this series on this website.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 5a: Arithmetic instructions

* Four arithmetic instructions

# ADD
# SUB
# MUL
# DIV

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| '''LDmicro''' has 4 Arithmetic instructions.

They are '''Add, Subtract, Multiply''' and '''Divide'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 5b: Arithmetic instructions

* Can only handle 16-bit signed '''integer''' values
* Floating point numbers are not handled by these instructions

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| In '''LDmicro''', these instructions can handle only up to 16 bit signed '''integer''' values.

'''Floating point''' numbers are not handled by these instructions.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Now, we’ll learn about working of these instructions.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Open LDmicro
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Let us open '''LDmicro'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Let us start with an example of the '''ADD''' instruction.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Instructions -> Insert Contact >> Place the cursor to the right of the contact >> Click ‘Instructions -> Click on Arithmetic operator -> Insert ADD
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| First, place a '''Contact''' from '''Instructions'''.

Next to the right of it insert an '''ADD''' instruction as shown.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on contact >> Type switch in name box >> Click OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Rename the '''Contact''' as '''‘switch’'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ADD 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Now, double click on the '''ADD''' instruction.

A dialog box opens which has three inputs.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight Destination

Enter ‘result’

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| First, we have '''Destination'''.

It should be the '''variable''' name to which you want to save the result.

Enter the '''variable''' name as '''‘result’'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight ‘is set to := :’ and ‘+ :’

Type 4 in ‘is set to :=’ column 

Type 5 in ‘+:’ column

Click OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Then the next two columns are '''operands'''.

These can be either '''constants''' or '''variables'''.

Enter the '''operands''' as 4 and 5 respectively.

Click on the '''OK''' button.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight ‘result’ in I/O list
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Observe that the type of '''‘result’''' is shown as a '''general variable.'''

Also we can observe that there is no prefix before its name.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Note that the '''variables''' can also be '''timer''' and '''counter variables'''. 

We will learn about these '''variables''' in the later tutorials.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| We will now check the working of this '''logic'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Let us turn '''ON''' the '''simulation mode'''.

For that, click '''Simulate''' and then on '''Simulation mode.'''

Next, start '''real-time simulation''' as shown.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight Xswitch and result in the IO list
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Initially the state of '''Xswitch''' and '''result''' are 0.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ‘Xswitch’ 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the state of '''Xswitch''' to 1.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight the state of the ‘result’
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| We can observe the value of '''variable ‘result’''' changes to 9.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click on Simulate >> Click on Halt simulation >> Click on Simulation Mode
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Turn '''OFF''' the '''simulation mode'''.

For that, click '''Simulate''' and then on '''Halt Simulation.'''

Then click '''Simulate''' and '''Simulation Mode.'''

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ADD >> Change second operand to 40000 >> Click the OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the second '''operand''' in the '''ADD''' instruction to 40000.

Click the '''OK''' button.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Simulate -> Simulation mode 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Turn '''ON''' the '''Simulation mode'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight the text ‘Constant 40000 out of range: -32768 to -32767’

Click the OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| A dialog box appears.

It says '''‘Constant 40000 out of range: -32768 to 32767 inclusive’.'''

This means that '''operands''' should be signed 16-bit '''integers'''.

Click the '''OK''' button.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ADD >> Change second operand to 32767 >> Click the OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Now change the second '''operand''' to 32767 as shown.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Start '''real-time simulation.'''

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on Xswitch
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the state of '''Xswitch''' to 1.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight the state of the ‘result’
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| We can observe that the value of the '''‘result’''' changes to '''‘-32765’'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| That is, the result of the '''ADD '''operation is also a signed 16-bit '''integer'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ‘switch’ in the IO list >> Double-click on ‘switch’ in the IO list >>

Highlight the state of the ‘result’
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the state of '''Xswitch''' to 0.

And then again to 1.

We can observe that the state of the '''variable ‘result’''' doesn't change.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Thus the '''ADD operation''' happens only once.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Now, we will try to increment a '''variable''' on every '''switch''' press.

Also, we will understand the importance of '''One shot '''instructions.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click on Halt simulation >> Click on Simulation Mode
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Turn '''OFF''' the '''simulation mode''' as shown.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ADD >> Change second operand to result >> Click the OK button
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double click on the '''ADD''' instruction.

Change the second '''operand''' to '''variable ‘result’'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Start '''real-time simulation''' as shown.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ‘switch’ in the IO list
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the state of '''Xswitch''' to 1.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight the state of the ‘result’
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| We can observe that the value of '''‘result’''' keeps changing rapidly. 

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| It keeps updating until the state of '''Xswitch''' is 1.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click on Halt simulation >> Click on Simulation Mode
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Turn '''OFF''' the '''simulation mode'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide: How can we prevent PLC from evaluating the instruction on each cycle?

We can do that by using a '''One Shot''' instruction.
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| How can we prevent '''PLC''' from evaluating the instruction on each '''cycle'''?

We can do that by using a '''One Shot''' instruction.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Let us try doing this on '''LDmicro'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Place the cursor to the right of the contact >> Click on Instructions -> Insert OSR
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Place an '''OSR''' to the right of '''Xswitch'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Start '''real-time simulation.'''

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Double-click on ‘switch’ in the IO list
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Change the state of '''Xswitch''' from 0 to 1.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Highlight the state of the ‘result’
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| We can observe that the state of the '''variable ‘result’''' changes to 4.

That is, '''ADD operation''' happens only once.

Change the state of '''Xswitch''' back to 0.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Again change the state of '''Xswitch''' from 0 to 1.

We can observe that the state of the''' 'result'''' changes to 8.

That is, '''ADD operation''' happens only when input changes its state from low to high.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click on Simulate >> Click on Halt simulation Click on Simulate >> Click on Simulation Mode
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Turn '''OFF''' the '''simulation mode'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘add.ld’ >> Click on Save
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Save the '''ladder diagram''' as '''add.ld'''.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 6: Assignment

* Replace an '''OSF''' in the place of '''OSR'''. Observe the '''‘result’''' variable.

'''Observation:'''

* The value changes when the '''input''' goes from high to low.
* That is when the state of Xswitch goes from 1 to 0.
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| As an assignment:

* Replace an '''OSF''' in the place of '''OSR''' and observe the '''‘result’ variable'''.

'''Observation:'''

* The value changes when the '''input''' goes from high to low.

* That is when the state of '''Xswitch''' goes from 1 to 0.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 7: When to use OSR/OSF?

* Use OSR, when you want the change in count to happen when the switch is pressed
* Use OSF, when you want the change to happen when the switch is released
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| When to use OSR or OSF?

* Use '''OSR''', when you want the change in count to happen when the '''switch''' is pressed
* Use '''OSF''', when you want the change to happen when the '''switch''' is released

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Next, we will look at other '''Arithmetic''' instructions.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 8: Arithmetic Instructions

* SUB, MUL and DIV work similar to ADD
* NOTE: DIV instruction gives quotient as the result
* Explore these instructions on your own.

| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| The instructions subtract, multiply, and divide work in the similar way as of addition.

Note that the '''Divide''' instruction gives quotient as the result.

Explore these instructions on your own.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| 
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| This brings us to the end of this tutorial.

Let us summarize.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 9: Summary

* Arithmetic instructions


| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| In this tutorial, we learnt about

* '''Arithmetic''' instructions
|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 10:

About Spoken Tutorial project
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 11:

Spoken Tutorial workshops
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| The''' Spoken Tutorial Project''' team:

* conducts workshops using spoken tutorials and
* gives certificates on passing online tests.

For more details, please write to us

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 12:

Forum for specific questions:
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Please post your timed queries in this Forum.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 13:

Forum for specific questions:
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Do you have any general / technical questions on OpenPLC?

Please visit the FOSSEE forum and post your question.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 14:

Acknowledgement
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Spoken Tutorial Project is funded by MHRD, Government of India.

|-
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| Slide 15:

Thank you slide
| style="background-color:#ffffff;border:1pt solid #000001;padding:0.176cm;"| This tutorial has been contributed by FOSSEE and Spoken Tutorial Project, IIT Bombay.

And this is Harsha Priyanka from FOSSEE team, signing off.

Thanks for watching.

|}