Programable logic controllers (PLC) Essay Example | Topics and Well Written Essays - 750 words

Programable logic controllers (PLC) - Essay Example On its site, Wikipedia says a PLC is used for the automation of electromechanical processes for example controlling factory machinery or running amusement rides. It says that its function is unlike a computer that is built for a general purpose, and that it is designed to accommodate multiple inputs and output arrangements, resistant to vibrations, impact or temperature changes. The controlling programs are generally stored in a non-volatile memory as these controllers operate in different kinds of environment, fitted into machines where the controlling program must be kept stable at all times. They are designed for real-time use and are often subjected to extreme environments where it cannot afford to malfunction; its circuitry keeps a check on multiple sensor inputs which control the output actuators, for example, solenoids, lights and valves (Blacharski, 2003). The first Programmable Logic Controller to be developed was by General Motors in 1968 when its Hydramatic Division wanted to counter the soaring costs involved in the existing inflexible relay-controlled systems. The starting PLCs had relay functionality, substituting the traditional hard-wired relay logic which used electrically run devices to mechanically switch circuits. They offered a lot of advantage as they were far easier to use in an industry; the installation wasn’t tough, they needed less space and they were re-usable. The benefit of PLCs quickly caught on to other businesses like food, beverage and manufacturing and by 1971, they were providing relay replacement which was the first step to contr ol automation (Bryan and Bryan 1997, 16-18). The CPU, consisting of the processor, memory system and the power supply runs all PLC activities. The I/O system is physically connected to devices used in the control of a process or machine and its interface provides the connection between the CPU, the information providers