What are the four languages used to program a CompactLogix PLC?

The correct answer identifies the four primary programming languages used for CompactLogix PLCs: sequential function chart, structured text, function block diagram, and ladder programming. These languages are defined in the IEC 61131-3 standard, which governs the programming of industrial automation systems, including Programmable Logic Controllers (PLCs).

Sequential function chart is particularly useful for representing processes that require a sequence of operations, allowing for clear visualization of control steps. Structured text provides a high-level programming environment similar to traditional programming languages, offering advanced features for complex mathematical operations and data handling. Function block diagram allows for intuitive graphical programming by connecting function blocks that represent operations. Lastly, ladder programming mimics electrical relay logic, making it easy for those with electrical backgrounds to understand and implement.

Each of these languages serves specific needs and provides versatility in programming and configuring the PLC to efficiently perform various control tasks. As a result, understanding and utilizing these programming languages can significantly enhance the effectiveness of control systems in industrial applications.