Introduction to PLC and Types of Control System
Programmable Logic Controllers ( PLCs ), are in the computer family. They are used in industrial applications. A PLC oversee inputs, run its control program then makes decisions , and controls outputs to make a process or machine run automatically. I will discuss basic information on the of PLCs functions and configurations
History of PLC
Since the Industrial Revolution of the 18th-and 19th-centuries, many traditionally manual processes were replaced by machines. These early machines relied on gears and pulleys to work and were aboriginal. The first control system came with the invention of electrically powered machines. The first control systems were developed in the beginning of the 20th century with sequential Relay Circuits for machine control. Relay is A major technical breakthrough in its day, and still used in some plants today, relay technology made machines to work faster and more safely.
Relay circuits performed their job very well, but they have some drawbacks requiring large space, huge amounts of energy needed. Adding to their drawbacks as the basis for a machine control system, relay circuits also took a long time to install, troubleshoot, and modify. Finally, in the 1969s, the Programmable Logic Controller (PLC) was developed to replace sequential relay circuits: .
PLCs are more reliable, faster, more flexible and more efficient than relay systems.PLCs are cheaper and easier to wire and maintain than relays. Furthermore, when PLC comes to troubleshooting, PLCs are much quicker than relays at testing and debugging the program.
PLCs are used in all kinds of industries. In fact, almost any industrial process that uses electrical control needs a PLC. For example, when a switch turns on we want to turn a motor on for 30 seconds and then turn it off irrespective of how long the switch is on. this can do with an external timer. But in the real process it include more than 10 switches and Motors? We would need more than 10 external timers. as well as the process also needed counters. With a PLC, we can dispense with those unwieldy timers and counters, and simply program the PLC to count its inputs and turn the motors on for the specified time.
Reference:Panasonic training course
