Programmable Logic Controller – A brief history of Modicon PLCs

PLC was invented by American inventor and engineer Dick Morley, an expert in computer design, artificial intelligence, and automation. In 1968, he invented the programmable logic controller. He was the head of the team that developed the first PLC while at Bedford & Associates. This invention was supported by the need to automate the General Motors production facility.

The first PLC was named the Modicon PLC. Modicon was a shortened name of the modular digital controller. When launched, this device revolutionized the industry. It changed the concept of automating industrial processes and machines.

In 1968, Modicon manficatured the Modicon PLCs. Later on, Modicon was owned by AEG. Today it is owned by Schneider. PLCs have passed many stages of development throughout the last 50 years. 

How does a Programmable Logic Controller automate an industrial application?

A person’s brain relies on data offered by the senses. Similarly, PLC needs instrumentation to calculate its surroundings. These are what we call PLC inputs. A PLC gathers data from devices and uses application software to define what actions to take.

The data gathered through the hardware is saved in the information memory, and the application program is saved in the program memory.

Plc is like the brain. As the brain controls what a body does, PLC manages the moves of a machine that uses electrical, pneumatic, and hydraulic devices. These are called PLC outputs. 

For example, imagine linking a programmable logic controller with input and output devices for a basic temperature control application. If you link a temperature sensor as the input to a PLC you can know how hot it is, and if you connect an electric fan as a programmable logic controller output you can adjust the temperature.

Keep in mind that a programmable logic controller’s level of automation is good as the quality of data gathered by the hardware and the quality of the application program in its memory. Therefore a good program with a logical expression will lead to a problem-free operation. 

The Programmable Logic Controller can manage industrial automation applications. PLC can manage an endless number of applications. 

Here are two examples: 

• Controlling the level of a water tank through watching the tank level and changing the inlet pump speed.
• The ability to control the temperature of the drying oven, through watching its internal temperature and repositioning the burner control valve.

If you are looking for additional information about Modicon, visit the MRO Electric website.