Which component in a PLC system is primarily responsible for executing programmed instructions?

The component primarily responsible for executing programmed instructions in a PLC system is the Central Processing Unit (CPU). The CPU functions as the brain of the PLC, executing the control logic and processing the information received from input devices. It interprets the programmed instructions written in the software and performs calculations, makes decisions, and controls the timing of the operations.

In addition to executing the program, the CPU also communicates with input and output modules, allowing it to respond to real-world signals and control devices accordingly. This central processing capability is essential for maintaining the logical flow and operational efficiency of the entire PLC system.

While input and output modules are crucial for data acquisition and device control respectively, they do not execute the program itself; rather, they enable the CPU to function effectively by providing the necessary data and executing commands based on the CPU's instructions. Data registers are used for storing information and intermediate results but do not play a role in executing the instructions written in the PLC program.