Chapter 6 Applied Instructions PID Block Diagram (Dependent) PID_DIR SV + - + 1 E PV REVERSE 0 X(-1) Kc_Kp >0 ERR_DBW Kc_Kp 0 BIAS PID_MAN + + + 0 Ti_Ki 1 MV >0 0 MV_MAX, MV_MIN Ti_Ki MOUT_AUTO MOUT PID-D Td_Kd MOUT PID_MAN 0 >0 1 0 Td_Kd, Tf 0 1 MOUT Suggestion: 1. Owing to the fact that the instruction DPIDE can be used in a lot of controlled environments, users have to select control functions appropriately. For example, the MV switches between the maximum output value and the minimum output value when PID_MODE is set to 1.
Please do not use DPIDE in the environment controlled by a motor which reacts rapidly, otherwise the violent change of the system resulting from the automatic tuning of the parameters may hurt the staff or damage the system. 2. When users tune the parameters Kc_Kp, Ti_Ki, and Td_Kd (PID_MODE is set to 0), they have to tune Kc_Kp first (according to their experiences), and then set Ti_Ki and Td_Kd to 0. When the users can handle the control, they can increase Ti_Ki and Td_Kd. When Kc_Kp is 1, it means that the proportional gain is 100%. That is, the error is increased by a factor of one. When the proportional gain is less than 100%, the error is decreased.
When the proportional gain is greater than 100%, the error is increased. 3. To prevent the parameters which have been tuned automatically from disappearing after a power cut, it is suggested that users should store the parameters in latching data registers if PID_MODE is set to 1. The parameters which have been tuned automatically are not necessarily suitable for every controlled environment. Therefore, the users can modify the parameters which have been tuned automatically. However, it is suggested that users only modify Ti_Ki or Td_Kd. 4. The action of the instruction depends on many parameters. To prevent improper control from occurring, please do not set parameters randomly.
6-191 DEAD BAND PID-P MV LIMIT _ PID-I