PLC Processor Module

A PLC Processor Module is the core computational component within a Programmable Logic Controller (PLC) system. It is responsible for executing the user-programmed control logic (ladder logic, function block diagrams, structured text, etc.), processing input signals from sensors and devices, performing calculations and data handling, and generating output signals to control actuators, motors, valves, and other industrial equipment. It manages the scan cycle, communication with other modules (I/O, communication, special function), and system diagnostics.

The processor module operates on a cyclic scan principle. Each scan cycle consists of: 1) Reading the status of all input modules and storing the data in an input image table. 2) Executing the user program logic sequentially, using the input image data and internal memory to solve the control logic and update an output image table. 3) Writing the output image table states to the physical output modules. 4) Performing housekeeping tasks like communication, self-diagnostics, and updating system status. It contains a microprocessor, memory (for operating system, user program, and data), and communication interfaces.