Mitsubishi Electric MELSEC iQ-R Series - Page 1402

1400
11 PROCESS CONTROL INSTRUCTIONS
11.7 Auto Tuning
■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).
• Adjustment rule
N method: The adjustment rule using the step response of Ziegler and Nichols is used.
• PID constants storing
The following processing is performed and the S.AT1 instruction is terminated.
Operation error
Integral constant T
I
(I) Derivative constant T
D
(D) Control method
T
I
0  Proportional control (P action) only
T
I
>0 T
D
0 PI control (PI action)
T
D
>0 PID control (PID action)
Control
method
Proportional gain K
P
(P) Integral constant T
I
(I) Derivative constant T
D
(D)
P 00
PI 3.33L0
PID 2L0.5L
• 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
Error code Error content
3400H An invalid operation (such as division by zero) is performed.
3402H Input data (s1) is a subnormal number or NaN (not a number).
3403H An overflow has occurred.
3405H 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
1
R×L
100
|AT1STEPMV|
×
0.9
R×L 100
|AT1STEPMV|
×
1.2
R×L 100
|AT1STEPMV|
×