Industrial Maintenance Technician Practice Test

The primary function of the PLC Central Processing Unit (CPU) is to execute a stored program. The CPU operates as the brain of the Programmable Logic Controller (PLC), processing input signals, running the control logic as defined in the program, and generating output signals to control machinery or processes.

Within the context of a PLC, the stored program consists of a sequence of instructions that dictate how the system should respond to various input conditions. The CPU continuously scans inputs, processes the operational logic, and updates outputs based on the programmed instructions. This continuous loop ensures that the PLC reacts in real time to changing conditions, which is vital in industrial automation settings.

While storing program data, converting control signals, and monitoring external conditions are important functions related to the overall operation of a PLC, they are secondary in nature to the fundamental role of executing the programmed control logic. The CPU must run the program effectively for the PLC to function correctly in controlling automated processes.