PLC (programmable logic controller)
also: PLC · IEC 61131-3 · ladder logic · OPC UA
A rugged industrial controller that runs logic for machines and processes, programmed in standardized languages such as ladder diagram and structured text.
PLCs read sensors and switches, run their control program in a fast repeating scan cycle, and drive outputs such as motors, valves and relays. They are built for harsh electrical environments, long service life and predictable timing, with modular I/O and industrial networking. IEC 61131-3 standardizes their programming languages, including ladder diagram, function block diagram, structured text and sequential function charts. OPC UA (IEC 62541) is widely used to exchange data between PLCs and higher-level systems.
For hardware startups the question is often build versus buy. A custom embedded controller is cheaper per unit at volume; a PLC brings proven industrial hardware, tooling that customers' technicians already know, and faster development at low volumes.
Founder takeaway
For industrial machines at low volume, consider a PLC before custom electronics; customers' maintenance technicians may expect one.
sources
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