OpenPLC-version1-with-LDmicro/C3/CTU-Counter/English
Visual Cue | Narration |
Slide 1: | Welcome to the spoken tutorial on CTU Counter |
Slide 2: Learning Objectives* Count up (CTU) counter | In this tutorial, we’ll learn about the working of
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Slide 3: System Requirements
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To record this tutorial I am using:
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Slide 4: Pre-requisites* Working of Contact, Coil and RESET instructions
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* To follow this tutorial, you should know the working of
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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. |
Slide 5: Counters
3 types of counters
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In LDmicro, we have 3 types of counters.
Count up which is represented as CTU. Count down which is represented as CTD and Count circular which is represented as CTC. |
Here first we will learn about CTU counter.
In this tutorial, we will create a logic to turn on an LED. The condition is when the switch is pressed for more than or equal to 3 times. | |
Open the LDmicro from the launcher bar | Let us open LDmicro. |
Click ‘Instructions -> Insert Contact’ >>
Place the cursor to the right of the contact >> Click ‘Instructions -> Insert Coil’ |
Insert a Contact and a Coil as shown. |
Double-click on Xnew >> Type switch in name box >> Click OK button | Rename the Contact as ‘switch’. |
Double click on the Ynew >> Rename it as ‘LED’ >> Click OK button | Then rename the Coil as ‘LED’.. |
Place the cursor to the right of the contact >> Click Instructions -> Counters -> Insert CTU | Place the cursor to the right of Xswitch.
Now Insert a CTU from Instructions as shown here. |
Double-click on Cnew | Double-click on the counter. |
In the name column, type count | We can observe there are two columns.
First one is for the name of the counter. Type ‘count’ in it. |
In the True if >= column type 3
Click the OK button |
Second column is the condition column ‘True if >=’.
Here, we have to enter the desired count value. We will enter 3 as the count value. Click on the OK button. Note that the name is prefixed by C by default. |
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 state of Xswitch, YLED and Ccount in the I/O list | We can observe initially the states of Xswitch, YLED and Ccount are 0. |
Double click on Xswitch in the I/O list | Double click on the Xswitch to change its state to 1. |
Highlight the state of Ccount and YLED | We can observe the state of the counter Ccount changes to 1.
But, the state of YLED is still 0. |
Double click on Xswitch | Now, change the state of Xswitch back to 0. |
Highlight the state of Ccount | We can observe the state of Ccount is still 1 |
That is the counter value updates only with the rising edge of its input. | |
Double click on Xswitch for 3 times | Change the state of Xswitch from 0 to 1 for a couple more times. |
Highlight the state of Ccount | After 3 low to high transitions of Xswitch, the state of Ccount reaches 3. |
Highlight the state of YLED | We can now observe the state of YLED changes to 1. |
Double click on Xswitch for 2 times | Change the state of Xswitch to 0.
Again change it back to 1. |
Highlight the state of YLED | The state of Ccount changes to 4.
We can observe that the state of YLED is still 1. |
Once the counter reaches desired count value, its output will always be 1.
This is because of the condition >= 3 in the CTU 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 Xswitch and PA0 to YLED. |
Click on Compile >> Click on Compile >> Go to Desktop/LDmicro folder >> Rename it as ‘ctu.hex’ >> Click on Save.
Click OK button |
Compile the logic as ctu.hex. |
Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘ctu.ld’ >> Click on Save | Then save the ladder diagram as ctu.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:ctu.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. |
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. |
ctu.png | Let us see the connection details now. |
ctu.png | Connect GND pin of the red LED of Traffic Light module to GND of the Mainboard.
Then connect +5V pin of red LED to PA0 pin of the Mainboard. |
ctu.png | 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. |
After making all the connections properly, turn on the power supply. | |
Initially the red LED will not glow. | |
It will glow only when the switch NO1 is pressed for at least three times.
So, press the switch NO1 for 3 times. | |
We can see the LED will be glowing even after the NO1 is released. | |
Turn off the power supply. | |
Slide 6: Resetting CTU
CTU counters can be reset using RES instruction |
In order to turn off the LED we need to reset the counter.
It can be done by using a RESET instruction as learnt in the RTO tutorial. |
This brings us to the end of this tutorial.
Let us summarize. | |
Slide 7: Summary* Count up (CTU) counter
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In this tutorial we learnt about working of * Count up counter |
Slide 8: Assignment* Draw a ladder diagram to turn on an LED when the switch is pressed for >= 5 times.
Hint: Use another Contact and RES instruction |
As an assignment do the following:
Hint: Use another Contact and RES instruction. |
Slide 9:
About Spoken Tutorial project |
The video at the following link summarises the Spoken Tutorial project.
Please download and watch it |
Slide 10:
Spoken Tutorial workshops |
The Spoken Tutorial Project team:* conducts workshops using spoken tutorials and
For more details, please write to us |
Slide 11:
Forum for specific questions: |
Please post your timed queries in this forum |
Slide 12:
Forum for specific questions: |
Do you have any general / technical questions on OpenPLC?
Please visit the FOSSEE forum and post your question. |
Slide 13:
Acknowledgement |
Spoken Tutorial Project is funded by MHRD, Government of India. |
Slide 14:
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. |