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PLC (Programmable Logic Controllers) typically use a specialized programming language designed for industrial automation. The most common languages used for PLC programming are:
Each of these languages is standardized by the IEC 61131-3 standard, which ensures that PLCs from different manufacturers can work with the same programming languages. Ladder Logic is the most popular because of its simplicity and familiarity to those with a background in electrical engineering.
- Ladder Logic (LD) – This is the most widely used PLC programming language. It resembles electrical relay logic diagrams, making it easy for electricians and engineers to understand and use.
- Structured Text (ST) – This is a high-level, text-based programming language similar to Pascal or C. It is used for more complex calculations and algorithms.
- Function Block Diagram (FBD) – A graphical programming language where functions (blocks) are connected by lines that represent the flow of data. It is often used for continuous control systems.
- Instruction List (IL) – A low-level programming language similar to assembly language. It's less common nowadays but is still supported by some PLCs.
- Sequential Function Chart (SFC) – A graphical programming language used to describe sequential operations, like state machines or steps in a process.
Each of these languages is standardized by the IEC 61131-3 standard, which ensures that PLCs from different manufacturers can work with the same programming languages. Ladder Logic is the most popular because of its simplicity and familiarity to those with a background in electrical engineering.