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


{| style="border-spacing:0;"
| style="border:1pt solid #000000;padding:0.176cm;"| <center>'''Visual Cue'''</center>
| style="border:1pt solid #000000;padding:0.176cm;"| <center>'''Narration'''</center>

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 1: 
| style="border:1pt solid #000000;padding:0.176cm;"| Welcome to the spoken tutorial on''' Compare instructions.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 2: Learning Objectives

* Compare instructions

| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial, we will learn about working of '''Compare''' instructions

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 3: System Requirements

* Ubuntu 18.04''' '''operating system
* LDmicro
* OpenPLC Mainboard
* 24V, 2A SMPS
* USBasp programmer
* Traffic LIght module
* Switchboard module

| style="border:1pt solid #000000;padding:0.176cm;"| To record this tutorial I am using:

* '''Ubuntu Linux 18.04''' operating system
* '''LDmicro'''
* '''OpenPLC Mainboard'''
* '''24V, 2A SMPS'''
* '''USBasp''' programmer
* '''Traffic Light''' module and
* '''Switchboard''' module

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 4: Pre-requisites

* Working of Move (MOV) instruction
* If not, please refer to the relevant tutorials from [https://spoken-tutorial.org/ Home | spoken-tutorial.org]

| style="border:1pt solid #000000;padding:0.176cm;"| 
* To follow this tutorial, you should know the working of '''Move''' instruction.
* If not, please refer to the relevant tutorials in this series on this website.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 5: Prerequisites - Hardware setup

hardware-prerequisite.jpg
| style="border:1pt solid #000000;padding:0.176cm;"| Connect''' SMPS''' and '''USBasp''' to the '''Mainboard''' as shown in the picture.

Keep these connections throughout this tutorial.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 6a: Compare instructions

Six types of compare instructions

# equals
# not equals
# less than
# less than or equal
# greater than
# greater than or equal

| style="border:1pt solid #000000;padding:0.176cm;"| In '''LDmicro''' we have six types of compare instructions.

They are 

# '''Equals'''
# '''not equals'''
# '''less than'''
# '''less than or equal'''
# '''greater than'''
# '''greater than or equal'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 6b: Compare instructions

* These instructions can be used to compare 

* a variable to a variable, 
* variable to a 16-bit signed constant

* Working of these instructions will be similar

| style="border:1pt solid #000000;padding:0.176cm;"| These instructions can be used to compare a '''variable''' to another '''variable'''.

Also when we want to compare a '''variable''' to a '''16-bit''' signed '''constant'''.

Working of these compare instructions will be similar.

But the '''functioning''' will be according to their names.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial we’ll learn about '''compare for equals''' instruction in detail.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Open LDmicro
| style="border:1pt solid #000000;padding:0.176cm;"| Let us open '''LDmicro.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| We will create a '''virtual circular counter''' using a '''compare for equals''' instruction.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click Instructions -> Insert Contact >> Place the cursor to the right of the contact >> Click instructions -> Insert OSR >> Place the cursor to the right of OSR >> Click Instructions -> Arithmetic instructions -> Insert ADD
| style="border:1pt solid #000000;padding:0.176cm;"| Insert a '''Contact.'''

To the right of it insert an '''OSR'''

To the right of '''OSR''' insert an '''ADD''' instruction as shown here.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on the contact >> Type switch in the name box >> Click OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Rename the '''Contact''' as '''‘switch’'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double click on ADD
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on the '''ADD''' instruction.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type in the destination and ‘is set as := ‘ columns ‘vcounter’
| style="border:1pt solid #000000;padding:0.176cm;"| '''Set''' the destination and first '''operand''' to ‘'''vcounter’''' meaning '''virtual counter'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click the OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Second '''operand''' is by default 1.

Don’t change that.

Click the '''OK''' button

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click Edit -> Insert Rung after
| style="border:1pt solid #000000;padding:0.176cm;"| Insert a '''rung''' below as shown. 

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| We will insert '''Compare for equals''' and '''Move''' instruction in the new '''rung'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Place the cursor in the new rung >> Click Instructions -> Comparison operators -> Insert EQU >> place the cursor to the right of the contact >> Click Instructions -> Insert MOV
| style="border:1pt solid #000000;padding:0.176cm;"| Place the cursor in the new '''rung'''.

Click on '''Instructions''' and then '''Comparison operators.'''

Select '''Insert EQU.'''

Next place the cursor to the right of the '''compare for equals''' instruction.

Click on '''Instructions''' and then select '''Insert MOV.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double click on Compare for equals >> Set the first column to vcounter >> Set the second column to 0 >> Click the OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on '''Compare for equals.'''

Compare the ‘'''vcounter’ variable''' with 4.

That is, set the first column to '''‘vcounter’''' and the second one to 4.

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

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on the MOV instruction >> Type vcounter in the destination column >> Type 0 in the source column >> Click the OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on the '''Move''' instruction.

Set the '''Destination variable''' as '''‘vcounter’''' and '''Source variable''' as 0.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| We will now check the working of this '''logic'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
| style="border:1pt solid #000000;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="border:1pt solid #000000;padding:0.176cm;"| Highlight the state of Xswitch and counter in the I/O list
| style="border:1pt solid #000000;padding:0.176cm;"| Initially, the state of '''Xswitch''' and '''vcounter''' are 0.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on ‘Xswitch’
| style="border:1pt solid #000000;padding:0.176cm;"| Change the state of '''Xswitch''' to 1.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Highlight the state of vcounter

| style="border:1pt solid #000000;padding:0.176cm;"| We can observe the state of '''vcounter''' changes to 1.

The state of '''vcounter''' increases by 1 every time there is a high to low transition in '''Xswitch'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on ‘Xswitch’ for 5 more times

Highlight the state of vcounter.
| style="border:1pt solid #000000;padding:0.176cm;"| Keep changing the state of '''Xswitch''' from 0 to 1 and back to 0.

We can observe '''vcounter''' takes values 0, 1, 2, 3 and then goes back to 0.

That is like a '''circular counter''' with count 3.

|-

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| For visualization purpose we will glow a '''LED''' whenever the '''vcounter''' value is 0.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click on Simulate >> Click Halt Simulation >> Click Simulation Mode
| style="border:1pt solid #000000;padding:0.176cm;"| Now, turn '''OFF''' the '''simulation mode'''.

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

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

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Visual cue

Click Edit -> Insert rung after
| style="border:1pt solid #000000;padding:0.176cm;"| Insert a '''rung''' below the second '''rung'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Place the cursor in the new rung >> Click on Instructions -> Comparison Operators -> Insert EQU >> Place the cursor to the right of EQU >> Click on Instructions -> Insert Coil
| style="border:1pt solid #000000;padding:0.176cm;"| Place a '''Compare for equals''' and a '''Coil''' in the new '''rung'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on EQU instruction >> Type vcounter in the first box >> Type 0 in the second box >> Click OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on '''Compare for equals'''.

Compare the ‘'''vcounter’ variable''' with 0.

That is, set the first column to '''‘vcounter’''' and the second one to 0.

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

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on Ynew >> Type LED in the name box >> Select SET-only option >> Click OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Rename the '''Coil''' as '''LED.''' 

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Highlight the third rung
| style="border:1pt solid #000000;padding:0.176cm;"| Thus this will energise the '''YLED''' whenever the '''vcounter''' value is 0. 

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| Now let us '''compile''' the '''logic'''.

The detailed steps on how to '''compile''' and save the '''logic''' are explained in the earlier tutorials.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click on Settings >> Click on Microcontroller >> Select AVR ATmega16 40-PDIP 

Click on Settings >> Click on MCU parameters >> Change Crystal frequency to 16
| style="border:1pt solid #000000;padding:0.176cm;"| Click on '''Settings''' and select the '''microcontroller AVR ATmega16 40-PDIP.''' 

Adjust its '''parameters''' as shown here.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Double-click on Xswitch in I/O list >> Select PC0 >> Click OK button

Double-click on YLED in I/O list >> Select PA0 >> Click OK button
| style="border:1pt solid #000000;padding:0.176cm;"| Assign '''pin PC0''' to '''Xswitch''' and '''PA0''' to '''YLED'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click on Compile >> Click on Compile >> Go to Desktop/LDmicro folder >> Rename it as ‘compareequals.hex’ >> Click on Save.

Click OK button
| style="border:1pt solid #000000;padding:0.176cm;"| '''Compile''' the '''logic''' as '''‘compareequals.hex’.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘compareequals.ld’ >> Click on Save
| style="border:1pt solid #000000;padding:0.176cm;"| Then save the '''ladder diagram''' as '''‘compareequals.ld’.'''

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| We will now see the working of this '''logic''' on hardware.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Connect Mainboard to PC using USBasp

laptop-usbasp.jpg

| style="border:1pt solid #000000;padding:0.176cm;"| Connect the '''Mainboard''' to your laptop using '''USBasp'''.

Turn '''ON''' the '''power supply'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Open terminal >> Type cd Desktop/LDmicro >> Press ENTER >> type ‘'''avrdude -c usbasp -p m16 -U flash:w:compareequals.hex’ '''>> Press ENTER
| style="border:1pt solid #000000;padding:0.176cm;"| Open the '''Terminal''' by pressing '''CTRL+ALT+T''' keys simultaneously.

Go to the folder where you have saved the '''hex file'''.

Type the '''command''' as shown to upload the '''hex file''' to the '''Mainboard'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Remove the '''USBasp''' connection from the laptop.
| style="border:1pt solid #000000;padding:0.176cm;"| Turn '''OFF''' the '''power supply'''.

Remove the '''USBasp''' connection from the laptop.

This will prevent any hardware damage.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| compareequals.png
| style="border:1pt solid #000000;padding:0.176cm;"| Let us see the connection details now. 

|-
| style="border:1pt solid #000000;padding:0.176cm;"| compareequals.png
| style="border:1pt solid #000000;padding:0.176cm;"| Connect '''GND''' pin of the red LED of '''Traffic Light''' module to '''GND''' of the '''Mainboard'''.

Then connect '''+5V pin''' of the red LED to '''PA0''' pin of the '''Mainboard'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| compareequals.png
| style="border:1pt solid #000000;padding:0.176cm;"| Connect '''GND''' and '''5V''' of '''Switchboard''' to GND and 5V of the '''Mainboard''' respectively.

Then connect '''NO1''' of the '''Switchboard''' to '''PC0''' of the '''Mainboard'''.

Make the connections as shown in the picture.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| After making all the connections properly, turn '''ON''' the '''power supply'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| We can observe that the '''LED''' will be glowing initially.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| It will turn '''OFF''' once the '''NO1''' is pressed.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| The red '''LED''' will glow again after pressing '''NO1''' for 3 more times.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| Thus '''LED''' glow indicates that the count value of the counter is 0. 

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| Turn '''OFF''' the '''power supply'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| Try out the remaining '''Compare''' instructions on your own.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| 
| style="border:1pt solid #000000;padding:0.176cm;"| This brings us to the end of this tutorial.

Let us summarize.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 7: Summary

In this tutorial, we learnt about

* Compare instructions

| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial, we learnt about '''Compare''' instructions
|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 8: Assignment

Try to 

# Turn '''ON''' a '''LED''' whenever the '''count process''' is '''ON''' and 
# Turn '''OFF''' when count value becomes zero

Hint: Use '''‘greater than’ compare''' instruction to turn '''ON''' the '''LED'''.
| style="border:1pt solid #000000;padding:0.176cm;"| As an assignment, try to 

# Turn '''ON''' a '''LED''' whenever the '''count process''' is '''ON''' and 
# Turn '''OFF''' when count value becomes zero

Hint: Use '''‘greater than’ compare''' instruction to turn '''ON''' the '''LED'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 9:

About Spoken Tutorial project
| style="border:1pt solid #000000;padding:0.176cm;"| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 10:

Spoken Tutorial workshops
| style="border:1pt solid #000000;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="border:1pt solid #000000;padding:0.176cm;"| Slide 11:

Forum for specific questions:
| style="border:1pt solid #000000;padding:0.176cm;"| 
* Please post your timed queries in this forum.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 12:

Forum for specific questions:
| style="border:1pt solid #000000;padding:0.176cm;"| Do you have any general / technical questions on OpenPLC?

Please visit the FOSSEE forum and post your question.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 13:

Acknowledgement
| style="border:1pt solid #000000;padding:0.176cm;"| Spoken Tutorial Project is funded by MHRD, Government of India

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Slide 14:

Thank you slide
| style="border:1pt solid #000000;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.

|}