How Program Logic Controllers Work For Us

In our modern era, people no longer need to perform many of the onerous and dangerous tasks that once required a human’s direction and action. In the early days of the age of the machine, it was people standing on the factory production line sorting components, riveting them together, painting them, and all the other necessary steps in putting together a product, all whilst the various pieces passed by on a production line conveyor belt, a harsh environment to be sure. This type of job held the Three D rating- Dirty, Difficult, and Dangerous. Many people were maimed and injured when accidents on the line invariably took place, it was a soul-sucking job that placed high physical and mental demands on the worker.

Then came the age of electronics and everything changed! Now the majority of these kinds of tasks are handled by machines that are guided by a kind of electronic brain, the program logic controller, or “PLC” for short, an extremely robust computer that can withstand the harsh factory floor environment. It has no mouse, keyboard or monitor because it needs no human operator present, PLCs automatically control and monitor a large number of sensors and actuators on their own. This advanced technology has resulted in great boons for both the safety and well-being of human workers and the ability of production to move at a much faster pace now that machines are managing themselves during the production process.

So, how exactly do programmable logic controllers work?

Every PLC system contains three modules, the CPU module, the power supply module, and one or more input/output (I/O) modules.

The CPU Module – This module consists of a central processor and a memory component. This processor performs the required data computations and processing by receiving inputs and then producing the corresponding outputs required.

The Power Supply Module – The circuitry of the PLC’s computer runs on a 5V DC output supplied by the power supply module, which is responsible for providing power to the system by receiving AC power and converting it into DC power the two other modules (CPU and input/output modules) can use.

The I/O Modules – The input/output modules are the components responsible for connecting the sensors and actuators that sense the different parameters such as pressure, temperature, and flow to the PLC system. The I/O modules can be either digital or analogue.