OpenPLC-with-LDmicro/C2/Internal-Relay-and-Output-pin/English

Visual Cue	Narration
Slide 1:	Welcome to the spoken tutorial on Internal Relay and Output pin
Slide 2: Learning Objectives Types of sources available for Contacts/Coils Internal Relay Output pin	In this tutorial we will learn about, Types of sources available for Contacts/Coils. (i.e) Internal Relay and Output pin.
Slide 3: System Requirements Ubuntu 18.04 OS 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 Normal Contact and Coil Negated Contact and Coil	To follow this tutorial, you should know the working of Normal Contact and Coil Negated Contact and Coil 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.
	First we will understand the working of an Internal Relay.
Slide 5: Internal Relay It can be thought of as a variable inside a PLC memory bit It does not affect the external I/O’s of the PLC	Internal relay can be thought of as a variable inside a PLC memory bit. It does not affect the external I/Os of the PLC.
Open LDmicro	Let us open LDmicro.
Insert ‘Instructions -> Insert Contact’ >> Place the cursor to the right of the contact >> Insert ‘Instructions -> Insert Coil’	Insert a Contact from Instructions. Then to the right of it, insert a Coil as shown.
Double click on the Contact >> Rename the contact as ‘switch’ >> Click OK button	Rename the Contact as ‘switch’.
Double click on the coil >> Select Internal Relay >> Rename it as ‘relay’ >> Click OK button	Double-click on the Coil. In the ‘Source’ column select ‘Internal Relay’. Then rename it as ‘relay’. Click the OK button.
Highlight the coil	We can see that ‘R’ is prefixed instead of ‘Y’ in the name which indicates relay.
Click ‘Edit -> Insert Rung After’	Let us add a new rung after the current rung.
Insert ‘Instructions -> Insert Contact’ >> Place the cursor to the right of the contact >> Insert ‘Instructions -> Insert Coil’	Insert a Contact and a Coil in the newly added rung as shown.
Double click on the contact >> Select Internal Relay >> Rename the contact as ‘switch’ >> Click OK button	Double click on the Contact. In the ‘Source’ column select ‘Internal Relay’. Then rename it as ‘relay’. Click the OK button.
Highlight ‘Rrelay’ in the IO list	In the I/O list we can observe there is only one ‘Rrelay’. Both Contact and Coil are represented by the same internal relay.
Double click on the coil >> Rename it as ‘LED’ >> Click OK button	Now rename the Coil as ‘LED’ as shown.
	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, Rrelay and YLED in the I/O list	Initially the state of Xswitch, YLED and Rrelay are 0.
Double-click on Xswitch	Change the state of Xswitch to 1.
Highlight the state of Rrelay and YLED	We can observe that the state of ‘YLED’ and ‘Rrelay' have changed to 1.
Double-click on Rrelay Highlight ‘Rrelay’ in the I/O list	Now double click on Rrelay. We can notice that we are not able to change the state of Rrelay. This is because the Internal relay operates in the internal logic of the PLC. It does not operate on the I/O pins directly.
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 PC0 pin to ‘Xswitch’ and PA0 to ‘YLED’.
Double-click on Rrelay in the I/O list Highlight the text in the dialog box >> Click the OK button	Double-click on Rrelay in the I/O list. A dialog box opens. It says that ‘Can only assign pin number to input/output pins’. Recall that Internal relay represents a variable inside PLC memory. Click on the OK button.
	Thus working of this example is similar to the ‘Normal Contact’ example.
	So we will skip the hardware part.
Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘internalrelay.ld’ >> Click on Save	Save the file as ‘internalrelay.ld’ as shown.
	We will now learn about the source type ‘Output pin’ of the contact.
Click File >> Click New	Open a new file in LDmicro.
Insert ‘Instructions -> Insert Contact’ >> Place the cursor to the right of the contact >> Insert ‘Instructions -> Insert Coil’	Insert a Contact and a Coil as shown.
Double click on the Contact >> Rename the contact as ‘switch’ >> Click OK button	Rename the Contact as ‘switch’
Double click on the Coil >> Rename it as ‘LED1’ >> Click OK button	Then rename the Coil as ‘LED1’.
Click Edit -> Insert Rung After >> Place the cursor in the newly added rung >> Click ‘Instructions -> Insert Contact’ >> Place the cursor to the right of the contact >> Insert ‘Instructions -> Insert Coil’	Insert a rung below. Again, insert a Contact and a Coil in the newly added rung.
Double click on the contact >> Select Output pin >> Rename the contact as ‘LED1’ >> Click OK button	Double click on the Contact. In the ‘Source’ column select ‘Output pin’. Then rename it as ‘LED1’. Click the OK button.
Highlight the name of the contact viz. YLED1	We can observe the name of the Contact is prefixed by Y and not X.
Double click on the coil >> Check the ‘Negated’ box >> Click OK button	Double-click on the Coil. Check the ‘Negated’ box and rename it as LED2. Click the OK button.
	We will now check the working of this logic.
Click ‘Simulate -> Simulation mode’ >> Click ‘Simulate -> Real-time simulation’	Start real-time simulation as shown.
Highlight the states of all the instructions	Initially the state of Xswitch and YLED1 are 0 and YLED2 is 1.
Double-click on Xswitch Highlight the state of YLED1 and YLED2	Now change the state of Xswitch to 1. We can observe that the state of the YLED1 changes to 1 and YLED2 to 0.
	That is the output of YLED1 is given as input to YLED2.
Click Simulate -> Halt Simulation >> Click Simulate -> Simulation Mode	Turn off the simulation mode as shown.
	Let us compile the logic.
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.
Highlight Xswitch pin number Double-click on YLED1 in I/O list >> Select PA0 >> Click OK button Double-click on YLED2 in I/O list >> Select PA1 >> Click OK button	We can observe that Xswitch has already been assigned pin PC0. Now, assign pin PA0 to ‘YLED1’ and PA1 to ‘YLED2’.
Click on Compile >> Click on Compile >> rename it as ‘output-pin.hex’ >> Go to Desktop/LDmicro folder >> Click on Save. Click OK button	Compile the logic as ‘outputpin.hex’ as shown.
Click on File >> Click on Save >> Rename it as ‘outputpin.ld’ >> Go to Desktop/LDmicro folder >> Click on Save	Then save the ladder diagram as ‘outputpin.ld’ as shown.
	Now we will 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:outputpin.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.
outputpin.png	Let us see the connection details now.
outputpin.png	Connect GND and 5V of Switchboard to GND and 5V of the Mainboard respectively. Then connect NO1 of the Switchboard to PC0 of Mainboard.
outputpin.png Point to the connections	Beside the yellow LED of Traffic Light module, you will see a +5V pin. Connect this +5V pin to 5V of the Mainboard. Connect the ‘EN' pin to the GND of the Mainboard. Connect the ‘L’ pin to PA0 of the Mainboard which represents YLED1. Connect the ‘Ri’ pin to PA1 of the Mainboard which represents YLED2. Make the connections as shown in the picture.
Switch on the power	After making all the connections properly turn on the power supply.
Point to green LED	Initially the left green LED will be glowing. Recall that bottom LED connections should be given logic low for an LED to glow.
Point the output	Now press the switch NO1. The right green LED starts glowing and the left one goes off at the same time.
	Thus the output of the left green LED acts as input to the right green LED.
Switch off the power	Turn off the power supply.
	This brings us to the end of this tutorial. Let us summarize
Slide 6: Summary Internal Relay Output pin	In this tutorial, we learnt about different source types such as Internal Relay Output pin
Slide 7: Assignment Draw a ladder logic to latch an LED Hint: The LED should turn on when a switch is pressed It should stay on even after it is released.	As an assignment, draw a ladder logic to latch an LED. Hint: The LED should turn on when a switch is pressed It should stay on even after it is released.
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Slide 12: Acknowledgement	Spoken Tutorial Project is funded by MHRD, Government of India.
Slide 13: 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.

Contributors and Content Editors

Nirmala Venkat