Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 1402

■PID constants calculation processing
The response speed (R), equivalent dead time (L), and AT1 step manipulated value (AT1STEPMV) are assigned to the
adjustment rule to calculate PID constants.
• Control method
The control method is selected according to the integral constant TI (I) and derivative constant TD (D).
Integral constant T (I)
I
0
T
I
T >0
I
• Adjustment rule
N method: The adjustment rule using the step response of Ziegler and Nichols is used.
Control Proportional gain K
method
P
1
R×L
PI
0.9
R×L
PID
1.2
R×L
• PID constants storing
The following processing is performed and the S.AT1 instruction is terminated.
• PID constants are stored in the gain (P), integral constants (I), and derivative constants (D).
• Auto tuning completion (BB16) is set to 1.
• The AT1 step manipulated value (AT1SETPMV) is subtracted from the manipulated value (MV) and the result is stored in the manipulated value (MV).
MV=MV-AT1STEPMV
Operation error
Error code
3400H
3402H
3403H
3405H
11 PROCESS CONTROL INSTRUCTIONS
1400
11.7 Auto Tuning
Derivative constant T

0
T
D
T >0
D
(P)
P
|AT1STEPMV|
×
100
|AT1STEPMV|
×
100
|AT1STEPMV|
×
100
Error content
An invalid operation (such as division by zero) is performed.
Input data (s1) is a subnormal number or NaN (not a number).
An overflow has occurred.
AT1 sampling period (AT1ST) < 0
AT1 timeout time (AT1TOUT1) < 0
AT1 timeout (after maximum ramp) time (AT1TOUT2) < 0
Execution cycle (T) < 0
(AT1 sampling period (AT1ST)execution cycle (T)) > 32767
(AT1 timeout time (AT1TOUT1)execution cycle (T)) > 32767
(AT1 timeout (after maximum ramp) time (AT1TOUT2)Execution cycle (T)) > 32767
(D) Control method
D
Proportional control (P action) only
PI control (PI action)
PID control (PID action)
Integral constant T
0
3.33L
2L
(I) Derivative constant T
I
0
0
0.5L
(D)
D