What happens during the scanning process of a PLC?

During the scanning process of a PLC, an essential phase occurs where the controller reads and processes all active input signals. This input scanning involves checking the state of each input device connected to the PLC, such as sensors, switches, and other control devices. The scanned input states are then stored in memory, allowing the PLC to understand the current conditions of the system it is controlling.

This step is crucial because the information gathered will determine the logical decisions made in the following steps of the scan cycle, which include executing the control logic and updating the outputs accordingly. Each scan cycle consists of reading inputs, executing the program code based on those inputs, and then updating the outputs, in that exact order, ensuring a systematic and organized approach to control operations.

The significance of this process reinforces the real-time control capabilities of PLCs, enabling them to respond to changes promptly and accurately, which is vital in manufacturing and automation environments.