The Omron temperature controller E5CK has the function of Ralay based Autotuning. I use it to control a heater. the setpoint is 46.0 degrees celsius. Let it autotune. In autotuning, the controller is switched to ON at 43.4 degrees celsius, and OFF at 46 degrees celsius. That is to say, The Height of Relay is 1.3 degrees celsius. The Period of oscillatory temperature is 144 seconds. In the Process, the lowest temperature is 43.3 degrees celsius, and highest temperature 47.0 degrees celsius. After autotuning, it get PID parameters, P=0.5,I= 22s,D=3s. Could anyone know how it get them.