PLCs (Programmable logic controllers): where did it all start?

Programmable logic controllers, or PLCs, form the backbone of industrial automation, and are responsible for the automation of complex machinery and ensuring process reliability, precision, and safety. These are used on production lines, robotic equipment, and they enable remote oversight, monitoring and control.

The Origins and Evolution of PLC Technology

Considering the state of the art and the power of PLCs to manage both the largest pieces of machinery and the most delicate processes, it might be surprising to learn that the technology is almost 60 years old. The first PLC was built for General Motors in 1968. The company needed rugged and easily programmable controllers to replace hard-wired relay logic systems, and Dick Morley, now considered the father of the PLC, is credited with having developed the first PLC. The “Modular Digital Controller” was soon improved and named Modicon 084, the number a reference to this being the 84th project of Morley’s company, Bedford Associates. 

Dick Morley, the father of the PLC

Before PLCs, changes in production lines necessitated a complete shutdown and physical rewiring of control panels, which involved the rewiring of hundreds to eventually thousands of relays, as systems became more complex. Maintenance and changes became increasingly time-consuming and expensive processes, and not sustainable in an industry that needed to make changes quickly between models.

The Evolution of Modicon 084 PLC Ownership

Bedford Associates founded the company Modicon to promote and service the 084 PLC. It was later sold to the German company known today as AEG. The current owner of the Modicon 084 PLC is the French multinational organisation Schneider Electric.

Today, modern PLCs offer numerous attractive advantages:

1. Efficiency: faster response times, reduced downtime, and enhanced precision, leading to higher production rates and cost savings.

2. Reliability: redundancy options, fault tolerance mechanisms, and predictive maintenance capabilities, ensuring that critical processes remain operational.

3. Cost savings: PLCs produce savings in labour costs, improve energy efficiency, and minimise material wastage, resulting in significant financial benefits for industries.

4. Scalability: the highly scalable nature of PLCs allow for the addition of new input / output modules, components and devices as operations expand or change.