OpenPLC-with-LDmicro/C3/Arithmetic-Instructions/English

Visual Cue	Narration
Slide 1:	Welcome to the spoken tutorial on Arithmetic Instructions
Slide 2: Learning Objectives Arithmetic instructions	In this tutorial we’ll learn about Arithmetic instructions
Slide 3: System Requirements Ubuntu 18.04 operating system LDmicro	To record this tutorial I am using: Ubuntu Linux 18.04 operating system LDmicro
Slide 4: Pre-requisites Working of One Shot instructions If not, please refer to the relevant tutorials from Home | spoken-tutorial.org	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.
Slide 5a: Arithmetic instructions Four arithmetic instructions ADD SUB MUL DIV	LDmicro has 4 Arithmetic instructions. They are Add, Subtract, Multiply and Divide.
Slide 5b: Arithmetic instructions Can only handle 16-bit signed integer values Floating point numbers are not handled by these instructions	In LDmicro, these instructions can handle only up to 16 bit signed integer values. Floating point numbers are not handled by these instructions.
	Now, we’ll learn about working of these instructions.
Open LDmicro	Let us open LDmicro.
	Let us start with an example of the ADD instruction.
Click Instructions -> Insert Contact >> Place the cursor to the right of the contact >> Click ‘Instructions -> Click on Arithmetic operator -> Insert ADD	First, place a Contact from Instructions. Next to the right of it insert an ADD instruction as shown.
Double-click on contact >> Type switch in name box >> Click OK button	Rename the Contact as ‘switch’.
Double-click on ADD	Now, double click on the ADD instruction. A dialog box opens which has three inputs.
Highlight Destination Enter ‘result’	First, we have Destination. It should be the variable name to which you want to save the result. Enter the variable name as ‘result’.
Highlight ‘is set to := :’ and ‘+ :’ Type 4 in ‘is set to :=’ column Type 5 in ‘+:’ column Click OK button	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.
Highlight ‘result’ in I/O list	Observe that the type of ‘result’ is shown as a general variable. Also we can observe that there is no prefix before its name.
	Note that the variables can also be timer and counter variables. We will learn about these variables in the later tutorials.
	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 Xswitch and result in the IO list	Initially the state of Xswitch and result are 0.
Double-click on ‘Xswitch’	Change the state of Xswitch to 1.
Highlight the state of the ‘result’	We can observe the value of variable ‘result’ changes to 9.
Click on Simulate >> Click on Halt simulation >> Click on Simulation Mode	Turn OFF the simulation mode. For that, click Simulate and then on Halt Simulation. Then click Simulate and Simulation Mode.
Double-click on ADD >> Change second operand to 40000 >> Click the OK button	Change the second operand in the ADD instruction to 40000. Click the OK button.
Click Simulate -> Simulation mode	Turn ON the Simulation mode.
Highlight the text ‘Constant 40000 out of range: -32768 to -32767’ Click the OK button	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.
Double-click on ADD >> Change second operand to 32767 >> Click the OK button	Now change the second operand to 32767 as shown.
Click Simulate -> Simulation mode >> Click Simulate -> Real-time simulation	Start real-time simulation.
Double-click on Xswitch	Change the state of Xswitch to 1.
Highlight the state of the ‘result’	We can observe that the value of the ‘result’ changes to ‘-32765’.
	That is, the result of the ADD operation is also a signed 16-bit integer.
Double-click on ‘switch’ in the IO list >> Double-click on ‘switch’ in the IO list >> Highlight the state of the ‘result’	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.
	Thus the ADD operation happens only once.
	Now, we will try to increment a variable on every switch press. Also, we will understand the importance of One shot instructions.
Click on Halt simulation >> Click on Simulation Mode	Turn OFF the simulation mode as shown.
Double-click on ADD >> Change second operand to result >> Click the OK button	Double click on the ADD instruction. Change the second operand to variable ‘result’.
Click Simulate -> Simulation mode >> Click Simulate -> Real-time simulation	Start real-time simulation as shown.
Double-click on ‘switch’ in the IO list	Change the state of Xswitch to 1.
Highlight the state of the ‘result’	We can observe that the value of ‘result’ keeps changing rapidly.
	It keeps updating until the state of Xswitch is 1.
Click on Halt simulation >> Click on Simulation Mode	Turn OFF the simulation mode.
Slide: How can we prevent PLC from evaluating the instruction on each cycle? We can do that by using a One Shot instruction.	How can we prevent PLC from evaluating the instruction on each cycle? We can do that by using a One Shot instruction.
	Let us try doing this on LDmicro.
Place the cursor to the right of the contact >> Click on Instructions -> Insert OSR	Place an OSR to the right of Xswitch.
Click Simulate -> Simulation mode >> Click Simulate -> Real-time simulation	Start real-time simulation.
Double-click on ‘switch’ in the IO list	Change the state of Xswitch from 0 to 1.
Highlight the state of the ‘result’	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.
	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.
Click on Simulate >> Click on Halt simulation Click on Simulate >> Click on Simulation Mode	Turn OFF the simulation mode.
Click on File >> Click on Save >> Go to Desktop/LDmicro folder >> Rename it as ‘add.ld’ >> Click on Save	Save the ladder diagram as add.ld.
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.	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.
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	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
	Next, we will look at other Arithmetic instructions.
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.	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.
	This brings us to the end of this tutorial. Let us summarize.
Slide 9: Summary Arithmetic instructions	In this tutorial, we learnt about Arithmetic instructions
Slide 10: About Spoken Tutorial project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it
Slide 11: 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 12: Forum for specific questions:	Please post your timed queries in this Forum.
Slide 13: Forum for specific questions:	Do you have any general / technical questions on OpenPLC? Please visit the FOSSEE forum and post your question.
Slide 14: Acknowledgement	Spoken Tutorial Project is funded by MHRD, Government of India.
Slide 15: 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