View source for OpenPLC-with-LDmicro/C3/CTD-Counter/English


{| border="1"
|-

| align=center| '''Visual Cue'''
| align=center| '''Narration'''
|- 
|| Slide 1: 
|| Welcome to the spoken tutorial on '''CTD Counter'''.
|- 
|| Slide 2: 

Learning Objectives
* Count down (CTD) counter
|| 

In this tutorial we’ll learn about working of '''Count down counter'''.
|- 
|| Slide 3:

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

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
|- 
|| Slide 4: Pre-requisites
* Working of '''CTU''' and '''Compare''' instructions
* If not, please refer to the relevant tutorials from [https://spoken-tutorial.org/ Home | spoken-tutorial.org]

|| 
* To follow this tutorial, you should know the working of 

# '''CTU '''and
# '''Compare''' instruction.
* If not, please refer to the relevant tutorials in this series on this website.

|- 
|| Slide 5: Prerequisites - Hardware setup

hardware-prerequisite.jpg
|| Connect''' SMPS''' and '''USBasp''' to the '''Mainboard''' as shown in the picture.

Keep these connections throughout this tutorial.
|- 
|| 
|| We will create an '''up-down counter''' to understand the working of '''CTD'''.
|- 
|| Open the LDmicro from the launcher bar
|| Let us open '''LDmicro'''.
|- 
|| Click on Instructions -> Insert Contact >> Place the cursor to the right of Xnew >> Click on Instructions -> Insert Coil
|| Insert a '''Contact''' and a '''Coil''' as shown. 
|- 
|| Double-click on Xnew >> Type ‘up’ in the name box >> Click the OK button
|| Rename the '''Contact''' as '''‘up’'''.

|- 
|| Place the cursor below Xup >> Click on Instructions -> Insert Contact
|| Now insert a '''Contact''' parallel to '''Xup'''.

Rename the new '''Contact''' as '''‘down’'''.
|- 
|| Place the cursor to the right of Xup >> Click Instructions -> Counters -> Insert CTU
|| To the right of '''Xup''' insert a '''CTU '''as shown here.
|- 
|| Double-click the Cnew >> Type count in the name column >> Click the OK button
|| Double click on '''CTU'''.

Rename the '''CTU''' as '''‘count’. '''

The '''condition''' value is by default 0.

Don’t change it. 
|- 
|| Place the cursor to the right of Xdown >> Click Instructions -> Counters -> Insert CTD
|| To the right of '''Xdown''' insert a '''CTD '''as shown here.
|- 
|| Double-click the Cnew >> Type count in the name column >> Click the OK button
|| Double click on '''CTD'''.

Just like '''CTU''' it has two columns, '''‘Name’''' and '''‘True if >=’'''.

Rename the '''CTD''' as '''‘count’.''' 

The '''condition''' value is by default 0.

Don’t change it.
|- 
|| Double-click on Ynew >> Select Internal Relay >> Type relay in the name box >> Click the OK button
|| Now configure the '''Coil''' as '''Internal Relay''' and rename it as '''‘relay’'''.
|- 
|| 
|| This is because here we don't need any physical output from '''CTU''' and '''CTD'''.
|- 
|| Click Edit -> Insert Rung below
|| Now place a '''rung''' below as shown here.
|- 
|| Place the cursor in the new rung >> Click on Instructions -> Comparison operators -> Insert GEQ
|| In the new '''rung''' insert a greater than or equal to '''Compare''' instruction.
|- 
|| Double-click on greater than or equal to Compare instruction >> Type Ccount in the ‘Closed’ if: column >> Type 3 in the >= column
|| Double-click on the '''Compare''' instruction.

Compare '''Ccount variable''' with 3.

That is in the '''Closed if''' column enter '''Ccount'''.

In the '''>= (greater than or equals to)''' column enter 3.

Click on the '''OK''' button.
|- 
|| Place the cursor to the right of Compare instruction >> Click on Instructions -> Insert Coil
|| Now to the right of it, insert a '''Coil'''.
|- 
|| Double click on Ynew >> Type LED in the name column
|| Rename it as '''‘LED’'''.
|- 
|| 
|| We will now check the working of this '''logic'''.
|- 
|| Click Simulate -> Simulation mode >>

Click Simulate -> Real-time simulation
|| Let us turn '''on''' the '''simulation mode'''.

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

Next, start '''real-time simulation''' as shown.
|- 
|| Highlight the states of all the instructions in the IO list
|| We can observe initially that the state of every instruction is 0 except for '''Rrelay'''.
|- 
|| Double click on Xup 
|| Double click on '''Xup''' to change its state to 1.
|- 
|| Highlight the state of Ccount
|| We can observe the state of the '''Ccount''' changes to 1.
|- 
|| Highlight the state of Ccount
|| Keep changing the state of '''Xup '''by double clicking on it until '''Ccount''' value reaches 3.
|- 
|| Highlight the state of YLED
|| We can observe the state of '''YLED''' changes to 1.
|- 
|| 
|| Just like in the '''CTU''' example.
|- 
|| Double click on Xdown 
|| Now change the state of '''Xdown''' to 1.
|- 
|| Highlight the state of Ccount
|| We can observe the '''Ccount''' value changes to 2.

That is decreased by 1.
|- 
|| Highlight the state of YLED
|| Also, the state of '''YLED''' goes back to 0.

The state of '''YLED''' will be 1 only when '''Ccount''' value is '''>= (greater than or equals to)''' 3.
|- 
|| Double click on Xdown 
|| Change the state of '''Xdown''' back to 0.
|- 
|| Highlight the state of Ccount
|| The value of '''Ccount''' is still 2.
|- 
|| Highlight the state of Ccount
|| The '''CTD''' decreases the count value by 1 only with the rising edge of its '''input'''.
|- 
|| 
|| Thus the working of '''CTU''' and '''CTD''' is similar.

The only difference is '''CTD''' decrements the '''counter''' value.
|- 
|| 
|| We can also reset the '''CTD''' using '''RESET''' instruction.
|- 
|| Click Simulate -> Halt Simulation >> Click Simulate -> Simulation Mode
|| Now, turn '''off''' the '''simulation mode'''.

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

Then click '''Simulate''' and '''Simulation Mode.'''
|- 
|| 
|| Now let us '''compile''' the '''logic'''.

The detailed steps on how to '''compile''' and save the '''logic''' are explained in the earlier tutorials. 
|- 
|| Click on Settings >> Click on Microcontroller >> Select AVR ATmega16 40-PDIP 

Click on Settings >> Click on MCU parameters >> Change Crystal frequency to 16
|| Click on '''Settings''' and select the '''microcontroller AVR ATmega16 40-PDIP.''' 

Adjust its '''parameters''' as shown here.
|- 
|| 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
|| Assign '''pin PC0''' to '''Xup '''and '''PC1''' to '''Xdown'''.

Assign '''pin PA0''' to '''YLED'''.
|- 
|| Click on Compile >> Click on Compile >> Go to Desktop/LDmicro folder >> Rename it as ‘ctd.hex’ >> Click on Save.

Click OK button
|| '''Compile''' the '''logic''' as '''ctd.hex.'''
|- 
|| Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘ctd.ld’ >> Click on Save
|| Then save the '''ladder diagram''' as '''ctd.ld.'''
|- 
|| 
|| We will now see the working of this '''logic''' on hardware.
|- 
|| Connect Mainboard to PC using USBasp

laptop-usbasp.jpg

|| Connect the '''Mainboard''' to your laptop using '''USBasp'''.

Turn '''on''' the '''power supply'''.
|- 
|| Open terminal >> Type cd Desktop/LDmicro >> Press ENTER >> type ‘'''avrdude -c usbasp -p m16 -U flash:w:ctd.hex’ '''>> Press ENTER
|| 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'''.
|- 
|| Turn off the power supply >> Remove the '''USBasp''' connection from the laptop.
|| Turn '''off''' the '''power supply'''.

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

This will prevent any hardware damage.
|- 
|| ctd.png
|| Let us see the connection details now. 
|- 
|| ctd.png >> point as per the narration
|| Connect '''GND pin''' of the red '''LED''' of '''Traffic Light''' module to '''GND''' of the '''Mainboard'''.

Then connect the '''+5V pin''' of the red '''LED''' to '''PA0''' pin of the '''Mainboard'''.
|- 
|| ctd.png >> point as per the narration
|| Connect '''GND''' and '''5V''' of '''switchboard''' to '''GND''' and '''5V''' of the '''Mainboard''' respectively.

Connect '''NO1''' to '''PC0''' of the '''Mainboard'''.

Then connect '''NO2''' to '''PC1''' of the '''Mainboard'''.

Make the connections as shown in the picture.
|- 
|| Turn on the power supply
|| After making all the connections properly, turn '''on''' the '''power supply'''.
|- 
|| Point to red LED
|| Initially the red '''LED''' will not glow.
|- 
|| Press NO1 three times to make it glow
|| It will glow only when '''NO1''' is pressed for at least three times.

So, press the switch''' NO1''' for 3 times.
|- 
|| 
|| Now the '''count''' value is 3.
|- 
|| Press the switch NO2 >> LED turns off

Turn off the power supply
|| Press the switch '''NO2'''.

The '''count''' value becomes 2 and the '''LED''' will turn '''off'''.

Thus '''CTD''' decreases the '''count''' value by 1 after every switch press.

Turn '''off''' the '''power supply'''.
|- 
|| Slide : Where can an up-down counter be used?
* The up-down counter can be used when we need to count finished products.
* CTU will increment the count value when a product is finished. 
* CTD will decrement the count of products that fail the quality test.

|| Where can an '''up-down counter''' be used?

The '''up-down counter''' can be used when we need to count the finished products.

'''CTU''' will increment the '''count''' value when a product is finished. 

'''CTD''' will decrement the count of products that fail the quality test.

|- 
|| 
|| This brings us to the end of this tutorial.

Let us summarize.
|- 
|| Slide 5: Summary
* Count down (CTD) counter

|| In this tutorial we learnt about working of '''Count down counter'''.
|- 
|| Slide 6:

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

Please download and watch it
|- 
|| Slide 7:

Spoken Tutorial workshops
|| The''' Spoken Tutorial Project''' team:
* conducts workshops using spoken tutorials and
* gives certificates on passing online tests.

For more details, please write to us
|- 
|| Slide 8:

Forum for specific questions:
|| Please post your timed queries in this Forum

|- 
|| Slide 19:

Forum for specific questions:
|| Do you have any general / technical questions on OpenPLC?

Please visit the FOSSEE forum and post your question.
|- 
|| Slide 10:

Acknowledgement
|| Spoken Tutorial Project is funded by MHRD, Government of India.
|- 
|| Slide 11:

Thank you slide
|| 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.
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