Programmable Logic Controller and ladder logic programming
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This document provides an introduction to programmable logic controllers (PLCs) and ladder logic programming. It defines a PLC as a small computer used to automate industrial processes by monitoring inputs and making decisions to control outputs based on a stored program. The document outlines the basic components of a PLC including input and output modules and the central processing unit. It then introduces ladder logic as the most common programming language for PLCs, describing the basic symbols of ladder diagrams including contacts, coils, and rungs. Finally, it provides examples of ladder logic programs for AND, OR, and NOT logic operations as well as timers and counters.
Programmable Logic Controller and ladder logic programming
- 1. Introduction to Programmable Logic Controllers and Ladder Logic
- 2. Welcome The purpose of this Presentation is to give you a very simple look Programmable Logic Controllers and its programming using Ladder Logic. There is no need for you to be familiar in any way with this field. The only requirement is that you enter with an open mind.
- 3. To begin with.. What is automation?
- 4. You may have come across the word “automated” very usually!
- 5. Automation is the use of machines, control systems and information technologies to monitor and control the production. In other words, an automated system is any system that require minimum or no human intervention.
- 6. Automation has made our life extremely simple.
- 7. Earlier, processes were carried out by operator, hence were much prone to human errors.
- 8. So we can imply that with Industrial control, factory automation, and PLC (if are done well), we can save a lot of time, materials, energy, and money.
- 9. Where do we begin?
- 10. Let’s recall the story of an explorer in Africa who asked the native tribesman,
- 11. How does one eat a huge animal like an elephant?" The tribesman looked at the explorer in astonishment and replied, "We eat it just like everything else, one bite at a time."
- 12. Simple as it is, industrial control is comprised of many smaller circuits. By exploring and learning simple smaller circuits, you can learn to build a complete automated system.
- 13. Programmable logic controllers Lets Start With… What is
- 14. a small computer with a built-in operating system which monitor inputs and other variable values, make decisions based on a stored program, and control outputs to automate a process or machine. Programmable logic controllers What is
- 15. Well, that was simple isn’t it ? Lets put it in another way..
- 16. A PLC is similar to a computer which is designed to be programmed once, and run repeatedly as needed.
- 17. Elements of PLC Let’s have al look at..
- 18. Input Modules Senses the input signal, isolates it and converts it to DC level.
- 19. Central Processor Unit (CPU) microprocessor system that contains the system memory and its decision making unit very similar to that of a computer’s CPU. Input Modules Senses the input signal, isolates it and converts it to DC level.
- 20. Output Module receives the convert control signals from the CPU and them converts them into digital or analog values that can be used to control various output devices. Central Processor Unit (CPU) microprocessor system that contains the system memory and its decision making unit very similar to that of a computer’s CPU. Input Modules Senses the input signal, isolates it and converts it to DC level.
- 21. Programming Device Personal computer or a Laptop And Communication Cable Output Module receives the convert control signals from the CPU and them converts them into digital or analog values that can be used to control various output devices. Central Processor Unit (CPU) microprocessor system that contains the system memory and its decision making unit very similar to that of a computer’s CPU. Input Modules Senses the input signal, isolates it and converts it to DC level.
- 22. PLC scan What is a
- 24. PLC scan
- 25. Programming PLC
- 26. The first and still most popular programming language used with PLC is Ladder Logic Programming (LAD).
- 27. They are called "ladder" diagrams because they resemble a ladder, with two vertical rails (supply power) and as many "rungs" (horizontal lines). The first and still most popular programming language used with PLC is Ladder Logic Programming (LAD).
- 28. Basic Ladder Logic Symbols Normally Open (NO) contact Passes power (on) when coil driving the contact is on. Contacts
- 29. Normally Closed (NC) contact Passes power (on) when coil driving the contact is off. Basic Ladder Logic Symbols Normally Open (NO) contact Passes power (on) when coil driving the contact is on. Contacts
- 30. Output or Coil When power flows through the Coils via contacts they are energized. Basic Ladder Logic Symbols
- 31. Schematic of ladder diagram
- 32. Selecting a PLC Criteria • Number of logical inputs and outputs. • Memory • Number of special I/O modules • Scan Time • Communications • Software
- 33. Functional Operation AND Operation OR Operation NOT Operation
- 34. Lets have a look at their truth table and Ladder Logic diagram
- 35. 35 AND Operation Both inputs S4 and S5 must be true (1) in order for the output L3 to be true (1). Ladder diagram
- 36. OR Operation Ladder diagram Either input S1 or S2 is true (1), or both are true, then the output L2 is true (1).
- 37. 37 NOT Operation If input S1 is be true (1), then the output L1 is true (0) or when A is (0), output C is 1. Ladder diagram
- 39. Timers On-Delay Timer (TON) Off-Delay Timer (TOF) Retentive On-Delay Timer (TONR)
- 40. Counters Count UP Counter (CTU) Count DOWN Counter (CDU) Count UP/DOWN Counter (CTUD)
- 41. ProgrammingExamples Lets start with simple examples…
- 42. Programming Examples D = (A AND B) OR C
- 43. Programming Examples Triggering the Relay Coil
- 44. Ladder Diagram for Triggering the Relay Coil
- 45. Learn the Basics of Programming Logic Controller & Ladder Logic by Downloading this E-book
- 46. This E-book contains Programmable logic controllers PLC Scan Basic Ladder Logic Symbols Functional Operation Programming Functions Programming To PLC (Practical Examples) Illustration of PLC Scan
- 47. For Further Reading Introduction to Programmable Logic Controller and Ladder Logic