At (Auto Tuning) Bias - Mitsubishi Electric MELSEC FX Series User Manual

FX -4LC User's Manual
3U
6.8.3

AT (auto tuning) bias

Set the auto tuning bias so that the measured value (PV) does not exceed the set value (SV) during auto
tuning.
The auto tuning function performs two-position control using the set value (SV), hunts the measured value
(PV), then calculates and sets each PID constant. However, for some control targets, overshoot caused by
hunting is not desirable. When the AT bias is set, the set value (SV) = AT point with which auto tuning is
performed can be changed.
Example of operation (When the AT bias is set to "-")
Measured value (PV)
Set value (SV)
AT point
Associated buffer memory
BFM No.
CH1 CH2 CH3 CH4
#1 #2 #3
#73 #113 #153 #193 Setting change ratio limiter
#74 #114 #154 #194 AT (auto tuning) bias
#76 #116 #156 #196 Setting limiter upper limit
#77 #117 #157 #197 Setting limiter lower limit
Caution
• When the set value (SV) added by the AT bias (AT point) value exceeds the setting limiter range, the 4LC
performs auto tuning using the setting limiter value.
• If the setting change ratio limiter is set to any value other than "0" when auto tuning is started, the set value
(SV) changes in accordance with the setting of the setting change ratio limiter until the AT point. When the
set value reaches the AT point, b14 "Auto tuning being performed" of the event buffer memory turns ON,
and auto tuning is started.
AT starts
#4 Event (b14 AT (auto tuning) being performed)
AT bias
AT finishes
Description
6 Introduction of Functions
6.8 Auto Tuning Function
Time
Reference
Subsection 8.2.2
Subsection 8.2.37
Subsection 8.2.38
Subsection 8.2.40
Subsection 8.2.41
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