Which of the following is a common programming language used for PLCs?

Ladder Logic Diagram (LLD) is widely used as a programming language for Programmable Logic Controllers (PLCs) due to its visual representation that mimics electrical relay logic diagrams. This format allows engineers and technicians, who may have a background in electrical engineering, to understand and troubleshoot control systems easily. Ladder Logic uses symbols to represent inputs and outputs, and its graphical nature makes it intuitive for programming complex control operations, such as sequencing, timing, and logic operations, without requiring deep knowledge of traditional programming.

In contrast, while Python, JavaScript, and C++ are powerful programming languages in their own rights, they are typically not utilized for direct PLC programming. Python is primarily used in scripting and automation tasks outside of real-time control applications. JavaScript is mainly employed for web development and not suited for the structured operational tasks handled by PLCs. C++ offers advanced programming capabilities and object-oriented features but does not provide the simplicity and straightforwardness of Ladder Logic for industrial control applications. This unique characteristic of LLD makes it the preferred choice for programming most PLCs in the industry.