What happens to the output state in a PLC during a scan cycle?

During a scan cycle in a PLC (Programmable Logic Controller), the output state is immediately updated based on input evaluation. This means that as the PLC goes through its cycle—which involves reading inputs, executing the control program, and then updating outputs—it evaluates the current inputs first. The results of this evaluation directly influence which outputs are activated or deactivated in real-time.

This immediate response to the input data is crucial for ensuring that the PLC can react quickly to changes in the system it is controlling. It allows for dynamic control of processes and machinery, ensuring that outputs reflect the most current status of inputs.

In essence, the PLC processes all input states promptly, and then adjusts the outputs according to the programmed logic, thereby maintaining an efficient and responsive control system. This methodology is fundamental for ensuring reliability and precision in industrial automation applications.