PROGRAMMABLE LOGIC CONTROLLER

 

PROGRAMMABLE LOGIC CONTROLLER

In 1968, the invention of the first PLC revolutionized the automation industry. First adopted by the automotive sector, General Motors began to deploy PLCs into their operations in 1969. Today, PLCs have broadly been accepted as the standard automated control system in manufacturing industries

A Programmable logic controller (PLC) is an industrial computer that has been adapted for the control of manufacturing processes, such as  machines, robotic devices, or any activity that requires high reliability, ease of programming, and process fault diagnosis. Dick Morley  is considered as the father of PLC.

PLCs can range from small modular devices with tens of Inputs and Outputs, in a housing integral with the processor, to large rack-mounted modular devices with thousands of I/O, and which are often networked to other PLC and SCADA  systems.

They can be designed for many arrangements of digital and analog I/O, extended temperature ranges, immunity to electrical noise , and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non -volatile memory..

PLCs were first developed in the automobile manufacturing industry to provide flexible, rugged and easily programmable controllers to replace hard-wired relay logic  systems. Since then, they have been widely adopted as high-reliability automation controllers suitable for harsh environments.

A PLC is an example of a hard real -time  system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result.                                    Important Parts of PLC: -