A Programmable Logic Controller (PLC) operates in a continuous cycle, executing a series of essential tasks to control industrial processes efficiently.

  • Operating System Initialisation: The operating system of the PLC starts, beginning the cycle and time monitoring.
  • Input Module Reading: The CPU begins reading data from the input module, checking the status of all connected inputs.
  • Program Execution: The CPU executes the user’s program, which is typically written in ladder logic or another PLC programming language.
  • Internal Diagnostics: The CPU performs all internal diagnostic and communication tasks.
  • Output Module Writing: Based on the program results, the CPU writes data to the output module to update all connected outputs.
  • Continuous Operation: This process continues indefinitely as long as the PLC remains in run mode.

This streamlined workflow allows PLCs to provide precise, reliable, and real-time control across various industrial applications.