The CPU communicates with the I/O – both generally within the same casing – which is connected to the electrical power source and the machines the PLC runs. Generally speaking, a PLC is used to control manufacturing processes such as automated assembly lines and robotic processes.Īlthough we can’t go too deep into the inner workings of a PLC, the high-level overview is that they generally comprise a central processing unit (CPU) module, a number of input-output (I/O) devices, which are sometimes part of the CPU or in other modules. In other words, PLCs are often attached to large, industrial machines. Harsh environments is generally understood to mean locations where there are strong vibrations, extreme temperatures and dirty and dusty atmospheres. The process of “ruggedisation” means that the PLC has been built using materials and components that are harder-wearing, longer-lasting and capable of operating in what are sometimes described as “harsh environments”. Moreover, panels of relay switches generally took up a lot more space than a programmable logic controller, and they used up more electrical power, and generated more heat and soot.Īnd although most of the time a programmable logic controller is about the size and approximate shape of a tablet computer, it is extensively ruggedised, which often makes it look like an iPad’s very rough cousin who has grown up in a brutal neighbourhood and town, and been in a lot of scraps. PLCs are estimated by one research company to reduce downtime from 20 percent to about 4 percent. Relays also require more operational downtime when they need to be reconfigured. Relays are devices that essentially turn machines on and off, and are said to be time-consuming and complex to use compared to PLCs.
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PLCs started out in the automotive manufacturing trade, although they can now be found in almost all sectors, where they tend to replace relays. Sometimes described as “the workhorse of industrial automation”, a programmable logic controller, or PLC, is a computing device that is specially designed for use in an industrial operation.Ī PLC can take many shapes and sizes, but in most instances it does not look like a conventional desktop computer like the ones you find in offices or in homes – a PLC has no display screen, no hard drive, and no keyboard.