7 Application Instructions API 50-99 d) There are a lot of circumstances where PID instruction can be applied; therefore, please choose the control functions appropriately. For example, when you select parameter auto-tuning for the temperature ( S 3 + 4 = K3), you cannot use it in a motor control environment in case improper control may occur. e) When you adjust the three main parameters, K P , K I and K D ( S 3 + 4 = K0 ~ K2), you have to adjust K P first (according to your experiences) and set K I and K D as 0. When you can roughly handle the control, you then adjust K I (increasingly) and K D (increasingly) (see example 4 below for how to adjust). K P = 100 refers to 100%, i.e.
the gain of the error is 1. K P P > 100% will increase the error. f) When you select the parameter exclusively for temperature control ( S 3 + 4 = K3, K4), it is suggested that you store the parameter in D register in the latched area in case the automatically adjusted parameter will disappear after the power is cut off. There is no guarantee that the adjusted parameter is suitable for every control. Therefore, you can modify the adjusted parameter according to your actual need, but it is suggested that you modify only K I or K D . g) PID instruction can to work with many parameters; therefore please do not randomly modify the parameters in case the control cannot be executed normally.
Example 1: Diagram of using PID instruction in position control ( S 3 + 4 = 0) PID Position instruction (SV) Example 2: Diagram of using PID instruction with AC motor drive on the control ( S 3 + 4 = 0) S+MV Speed instruction (S) AC motor drive Acceleration/deceleration output (MV) Acceleration/deceleration instruction (SV) PID Speed detection device (P) Actual acceleration/ deceleration speed (PV = S - P) Example 3: Diagram of using PID instruction in temperature control ( S 3 + 4 = 1) PID Temperature instruction (SV) Heating (MV) Heater Temperature detection device Actual temperature (PV) DVP-PLC APPLICATION MANUAL 7-139 MV Controlled device Encoder