The abbreviation of proportion, differentiation and integration in digital temperature controller is PID. \x0d\ Proportional adjustment (P) function: reflect the deviation of the system in proportion, and once the system has deviation, proportional adjustment will immediately generate adjustment function to reduce the deviation. A large proportion can speed up the adjustment and reduce the error, but a large proportion will reduce the stability of the system and even cause instability of the system. \x0d\ integral adjustment (1) Function: it is to make the system eliminate steady-state error and improve inertia. Because there is an error, the integral adjustment is carried out until there is no difference, the integral adjustment stops, and the integral adjustment outputs a constant value. The strength of integration depends on the integration time constant ti, and the smaller ti is, the stronger the integration is. On the other hand, if Ti is large, the integral effect is weak, and adding integral adjustment will reduce the stability of the system and slow down the dynamic response. Integration is usually combined with the other two regulation laws to form a PI regulator or a PID regulator. \x0d\ Differential regulation (d) function: Differential regulation reflects the rate of change of system deviation signal, which is predictive and can predict the trend of deviation change, so it can produce advanced control function, which has been eliminated by differential regulation function before the deviation is formed. Therefore, the dynamic performance of the system can be improved. When the appropriate differential time is selected, the overshoot and adjustment time can be reduced. Differential will amplify noise interference, so too strong differential regulation is unfavorable to the anti-interference of the system. In addition, the differential response is the rate of change, and the differential output is zero when the input is constant. Differential action can not be used alone, it needs to be combined with other two regulation laws to form a PD or PID controller. \x0d\ Digital temperature regulating controllers with PID regulating function all have PID self-tuning function. After setting the basic parameters, the digital temperature controller will enter self-tuning, and the thermostat will automatically determine the PID parameters during the heating process. It saves time more accurately than manual adjustment.