Appendix 3 Related Functions Of Process; Auto Tuning - Mitsubishi Electric MELSEC iQ-R Series Programming Manual

Appendix 3
This section describes functions related to process control.

Auto tuning

The auto tuning function detects dynamic characteristics of a control target and automatically tunes the proportional gain (Kp),
integral time (Ti), and derivative time (Td) for PID to suitable values.
The auto tuning function has two methods: step response method and limit cycle method.
Item
Overview
Applicable control mode
PID constants calculation
specification method
Corresponding tag access FB
Corresponding tag FB
For the execution and status check of the auto tuning, refer to the following.
 PX Developer Version 1 Operating Manual (Monitor Tool)
APPX
594

Appendix 3 Related Functions of Process

Related Functions of Process
AT1 (Step response method)
In this method, a proportional gain (Kp), an integral time
(Ti), and a derivative time (Td) for PID operations are
calculated with the ZN method (Ziegler-Nichols' step
response method) for setting their initial values.
MANUAL, COMPUTER MV
■P control tuning
Execute tuning after setting Ti = 0 and Td = 0.
■PI control tuning
Execute tuning after setting Ti > 0 and Td = 0.
■PID control tuning
Execute tuning after setting Ti > 0 and Td > 0.
• M+P_PID(_T)
• M+P_PID_DUTY(_T)
• M+P_2PID(_T)
• M+P_2PID_DUTY(_T)
• M+P_2PIDH(_T)_
• M+M_PID(_T)
• M+M_PID_DUTY(_T)
• M+M_2PID(_T)
• M+M_2PID_DUTY(_T)
• M+M_2PIDH(_T)_
AT2 (Limit cycle method)
In this method, a proportional gain (Kp), an integral time
(Ti), and a derivative time (Td) for PID operations are
calculated from the variation amplitude and variation cycle
of a process variable obtained by repeatedly outputting the
high and low limit values of a manipulated value.
The limit cycle method is less influenced by the process
variable noise compared to the step response method,
leading a stable tuning result.
AUTO, MANUAL, CASCADE, COMPUTER MV,
COMPUTER SV
Execute tuning by selecting the PI control or PID control
with the PX Developer monitor tool.
(Tuning only for the P control cannot be executed.)
• M+P_2PIDH(_T)_
• M+M_2PIDH(_T)_