A Programmable Logic Controller (PLC) is a specialized computer engineered for industrial purposes, specifically tailored for the control of manufacturing processes. It excels in environments demanding reliability, programmable functionalities, real-time data processing, and fault diagnosis. PLCs exhibit robustness, enabling them to endure challenging conditions such as extreme temperatures, electrical noise, vibration, and physical impact.
The timeline of the programmable logic controller can be traced back to the late 1960s, where its inception was driven by the need to replace relay logic systems prevalent in the United States automotive industry. Engineered for modularity and scalability, the initial iterations of PLCs embraced solid-state components, enabling the retention of programmed instructions even in the face of power interruptions. Dick Morley, engineer at Modicon Inc., is acknowledged as the inventor of the first PLC in 1969, characterized by a rudimentary relay design featuring four outputs, garnering rapid adoption within the automotive manufacturing sector.
As technology advanced, PLCs evolved from their large and expensive first-generation counterparts of the 1970s to become smaller, more powerful, and cost-effective. This evolution was marked by significant milestones such as the introduction of the IEC 61131-3 standard in 1982, which brought consistency to PLC software products. By the end of the 1990s, PLCs had begun to incorporate Ethernet connectivity, bringing megabytes of processor memory and user-defined data types to the factory floor.
