Programmable Logic Controllers; Understanding the Technology

The first PLCs were developed to serve the automobile industry. The very first PLC project was  in 1968 for General Motors with the aim of replacing hard-wired relay systems with electronic controllers. PLCs have remained widely used in this sector to date but other sectors and industries have also fully embraced these powerful machines.

Programmable logic controllers (PLCs) are miniature computers that control the automation of many electromechanical processes, like the movement of machines in an assembly plant.  The typical PLC features a programmable microprocessor that is programmed using a specialised computer language. The programs used in many programmable logic controllers like the Unitronics V1210 Black from All Drives and Controls are first written on a computer before being downloaded to the PLC via a cable connection. The program is stored in the PLC in non-volatile memory.

Programmable logic controllers generally contain a range of input and output ports and also make use of reduced instruction set computing (RISC).  RISC is made up of simplified instructions that are made to allow faster execution.

PLCs are typically designed for real-time use and need to be able to fully withstand hard factory environments, like high levels of heat or excessive vibrations. The circuitry of the programmable logic controller monitors the status of a variety of multiple sensor inputs that control output actuators like motor starters, displays, solenoids, valves and lights.

Benefits of the PLC systems

The major benefit of this type of controller is in the area of factory automation. Earlier automation systems needed to use thousands of individual relays, timers and sequencers that required replacement or rewiring each time there was need to change the automated process.

Most of the time, a programmable logic controller makes it easy for relays and timers within a factory system to be replaced by one controller. Modern PLCs feature a decent range of functionality including basic relay control, motion control, process control as well as complex networking. They can equally be deployed in places where there are distributed control systems (DCS).

Interfaces available

There are many types of interface that can be used by people to interact with programmable logic controllers to configure them or put them to work. The interface can be configured with nothing more than simple lights and switches and it could also include a text display. More complex systems can also use an internet-based interface on a computer that is running a supervisory control and data acquisition system.

Different industries need different types of PLCs but the bottom line is that PLC technology has greatly improved a lot of manufacturing sectors.