IEC 61131-3

IEC 61131-3 is the international standard for programming programmable logic controllers (PLCs) and automation systems. It defines five programming languages: Ladder Diagram (visual logic), Function Block Diagram (graphical blocks), Structured Text (text-based, C-like), Instruction List (low-level), and Sequential Function Chart (state machines). Engineers use IEC 61131-3 to program industrial machinery, manufacturing systems, power grids, and process automation. The standard ensures portability across different PLC vendors (Siemens, Allen-Bradley, Beckhoff, Mitsubishi) and provides real-time, deterministic execution crucial for safety-critical systems. IEC 61131-3 programs typically handle discrete I/O (inputs, outputs), timers, counters, and communication with other systems.