Bfm#74][Bfm#114][Bfm#154][Bfm#194] At (Auto Tuning) Bias - Mitsubishi Electric MELSEC FX Series User Manual

FX -4LC User's Manual
3U

8.2.38 [BFM#74][BFM#114][BFM#154][BFM#194] AT (auto tuning) bias

To these buffer memories, enter the AT bias to prevent the measured value (PV) from exceeding 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.
BFM No.
CH1 CH2 CH3 CH4
#74 #114 #154 #194 Setting range : -span to +span
*1. Input span for internal temperature input
Scaling span for internal micro voltage input
External input span for external input
Example of operation (When the AT bias is set to "-")
Measured value (PV)
Set value (SV)
AT point
Caution
• When handling numbers containing decimal places, multiply the set value by 10.
• If "Set value (SV) + AT bias" is outside the setting limiter range, auto tuning is performed using the setting
limiter value.
• If any value other than "0" is set to the setting change ratio limiter when auto tuning is started, the set value
(SV) changes in accordance with the setting change ratio limiter until the AT point. When the set value
(SV) reaches the AT point, b14 "AT being performed" of the event buffer memory turns ON and auto tuning
is started.
Description
AT starts AT finishes
→ For details on the setting change ratio limiter, refer to Subsection 8.2.37.
→ For details on the setting limiter upper limit, refer to Subsection 8.2.40.
→ For details on the setting limiter lower limit, refer to Subsection 8.2.41.
→ For details on the AT (auto tuning), refer to Section 6.8.
*1
AT bias
→ For details on the event, refer to Subsection 8.2.2.
8 Buffer Memory
8.2 Buffer Memory Details
Initial
R/W Backup
value
0 R/W
Time
101
1
2
3
4
5
6
7
8
9
10