PLC in 2026: A Brief Introduction to Programmable Logic Controllers
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PLC in 2026: A Brief Introduction to Programmable Logic Controllers
A Programmable Logic Controller (PLC) remains the backbone of factory automation in 2026.
Detail
This refreshed engineering note covers what a PLC is, how the IEC 61131-3 standard evolved,
and what changed since our 2024 overview , including OPC UA over MQTT, security hardening,
A PLC is an industrial, ruggedized computer that executes user-defined logic to control machinery in real time.
IEC 61131-3 (4th edition, 2025) keeps five languages: Ladder Diagram, Function Block, Structured Text, Instruction List, Sequential Function Chart.
Since 2024: OPC UA over MQTT, IEC 62443 cyber hardening, soft-PLC on industrial edge, and AI-assisted fault diagnostics have moved from pilot to production.
Classic families , Allen-Bradley ControlLogix 1756, Siemens S7-1500, Mitsubishi iQ-R, Omron NJ/NX , still anchor brownfield sites worldwide.
In short, the 2026 PLC is still a deterministic controller, now networked as a first-class
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