PLC wiring method of source type (NPN) and drain type (PNP)

Today’s closed-loop automatic control technologies are based on the concept of feedback to reduce uncertainty. The elements of feedback theory consist of three parts: measurement, comparison and execution. The key of measurement is the actual value of the controlled variable, compare with the expected value, use this difference to correct the system’s response, execute regulating control. In engineering practice, the control law of the most widely used regulator is proportion, integration and differentiation control, known as PID control.

What is the function of surge protector in the control system