Programmable logic controller contains seven units of instruction. The new control system had to meet the following requirements. These controllers can automate a specific process, machine function, or even an entire production line. Introduction of programming logic controller plc working. A programmable logic controller plc is a digital system used to make electrical and mechanical processes become automated. The first programmable logic controller plc was developed by a group of engineers at general motors in 1968, when the company were looking for an alternative to replace complex relay control systems. Plc can be found in almost all of the heavy industries which require process and sequences. A programmable logic controller plc, or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis. Due to its robust construction, exceptional functional features like sequential control, counters and timers, ease of programming, reliable controlling capabilities and ease of hardware usage this plc is used as more than a specialpurpose digital computer in. This book is an introduction to programmable logic controllers and aims to ease the tasks of practising engineers coming first into contact with programmable logic controllers, and also provides a basic course for students on courses such as nationals. The greatest benefit of automating with a programmable logic controller is the ability to repeat or change the operation or process while collecting and communicating vital information.
A plc control system organization in which a central plc controls several machines or processes. Programmable logic controller definition of programmable. Definition of programmable logic controller in the dictionary. The output ports of a plc are relay or opto isolator with transistor or triac, depending on the devices that are to be switched on or off. What does programmable logic controller actually mean. Programmable logic controller simple english wikipedia. A programmable logic controller plc or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability, ease of programming and process fault diagnosis plcs can range from small modular devices with tens of inputs and outputs. A programmable logic controller plc is a small, modular solid state computer with customized instructions for performing a particular task. Jackson lecture 32 basic addressing for the allenbradley plcs and the simulator used, the input and output image areas in addition to other data are held in data files each data file holds information such as. A programmable logic controller, or plc, is a ruggedized computer used for industrial automation. A programmable logic controller plc is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. Can be used standalone or in conjunction with a scada or other system.
Early machines were controlled by mechanical means using cams, gears, levers and. Programmable logic controller plc is a special computer device used in industrial control systems. It is a device that was invented to replace the necessary sequential relay circuits for machine control. The user can select which controllers will be used in the project microcontroller, programmable logic controller or both, and easily interconnect their pins to the peripheral modules, by using the implemented graphical. Simple programming program changes without system intervention. Pdf the concept of programmable logic controllers and its role. Programmable logic controllers continuously monitors the input values from various input sensing devices e. Programmable logic controllers nfi automation academy. Programmable logic controller plc is a microprocessor based. Information and translations of programmable logic controller in the most comprehensive dictionary definitions resource on the web. Plcs are integrated systems containing a processor, main memory, input modules, output modules that are coupled together by a common bus.
The logic of plc is programmed so that user can create a highly dedicated plc working system for their. This is a powerpoint presentation used to complete a requirement for a technical communications project in college. Frequently, a combination of different technologies is used. This second edition, like the first, provides a comprehensive theoretical, yet practical, look at all aspects of plcs and their associated devices and systems. A programmable logic controller, also called a plc or programmable controller, is a computertype device used to control equipment in an industrial facility. However, plcs can be thought of in simple terms as. Function block diagrams for programmable logic controllers. Unlike generalpurpose computers, the plc is designed for multiple inputs and output. Nemas definition nema or national electrical manufacturers association of a programmable logic controller is a. Programmable logic controllers, basic level textbook.
The web application controls the programmers for the user accessible microcontroller and programmable logic controller. Bolton, in programmable logic controllers sixth edition, 2015. Output devices in programmable logic controllers tutorial. Programmable logic controller a programmable logic controller plc is a specialized computer used to control machines and process. The following are some of the more common terms used to define the. It uses a programmable memory to store instructions and specific functions that include onoff control. The kinds of equipment that plcs can control are as varied as industrial facilities themselves. Plcs, which are used in industrial control systems for a wide variety of industries, have largely replaced mechanical relays, drum sequencers and cam timers.
A programmable logic controller plc is an industrial computer control system that continuously monitors the state of input devices and makes decisions based upon a custom program to control the state of output devices almost any production line, machine function, or process can be greatly enhanced using this type of control system. A typical block diagram of plc consists of five parts namely. Plcs operate in realtime which means that an event taking place in the field will result in. A programmable logic controller plc is an industrial solidstate computer that monitors inputs and outputs, and makes logicbased decisions for automated processes or machines. Automationdirect is your source for programmable logic controllers plcs. Define execution order for your tasks and programs. Today plcs can be found in everything from factory equipment to vending machines, but prior to new years day 1968 the programmable controller didnt even exist. Programmable logic controllers university of pennsyl vania 1 definition a digitally operated electronic apparatus which uses a programmable memory for the internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting, and arithmetic to control, through digital or. To respond to these phenomenal changes, we introduce the second edition of programmable controllers. Glossary of terms used in programmable controllerbased. Programmable logic controller article about programmable. Generally, the digital signal from an output channel of a plc is used to control an actuator, which in turn controls some process. They are basically used to control automated systems in industries.
Get unbeatable value on plc hardware, including fast shipping and free technical support. Programmable logic controller synonyms, programmable logic controller pronunciation, programmable logic controller translation, english dictionary definition of programmable logic controller. In the course of this work, the student will be presented with real world programming problems that can be solved on any available programmable controller or plc. Programmable logic controllers free download as powerpoint presentation. Furthermore, differentiation is made between hardwired programmable e. Programmable logic controllers plcs have been used in industry in one form or. Utility plants, batch control application, chemical processing, conveyor systems, food. They are one of the most advanced and simplest forms of control systems which are now replacing hard wired logic relays at a large scale.
A programmable logic controller plc is a special form of microprocessorbased controller that uses a programmable memory to store instructions and to implement functions such as logic, sequencing, timing, counting, and arithmetic to control machines and processes and is designed to be operated by engineers with. In essence, a plc is a special purpose industrial microprocessor based realtime computing system, which performs the following functions in the context of industrial. Find out inside pcmag s comprehensive tech and computerrelated encyclopedia. This second edition, like the first, provides a comprehensive theoretical, yet practical, look at all aspects of plcs and their associated devices and. Plc definition programmable logic controller program. A programmable logic controller is a mini computer specifically designed for industrial and other applications. Introduction to programmable logic controllers plcs. Those making the buying decisions for programmable controller. General definitions of plc size are given in terms of program memory size. It uses a programmable memory to store instructions and specific functions that include onoff control, timing, counting, sequencing, arithmetic, and data handling. A programmable logic controller plc is a special form of microprocessorbased controller that uses a programmable memory to store instructions and to implement functions such as logic, sequencing, timing, counting, and arithmetic to control machines and processes and is.
Programmable logic controller plc semantic scholar. A programmable logic controller plc is an industrial computer specialised for real time applications. It covers programable logic controllers and their implementation. The plc or programmable logic controller has revolutionized the automation industry. The plc receives information from connected sensors or input devices, processes the data, and triggers outputs based on preprogrammed parameters. This version of internet explorer is either no longer supported by microsoft, or is obsolete and some features of our store may no longer be supported. Plcs, which are used in industrial control systems for a wide variety of industries, have largely replaced mechanical relays.
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