Mitsubishi Electric MELSEC iQ-R Series User Manual page 298

CH1 AT bias
The point set as the set value (SV) of the auto tuning can be rearranged by using this area.
The auto tuning function determines each PID constant by executing the two-position control toward the set value (SV) and
causing hunting of the temperature process value (PV).
Set 'CH1 AT bias' (Un\G546) when an overshoot caused by the hunting is improper or the process value (PV) exceeds the set
value (SV) during the auto tuning.
The auto tuning is executed with having the AT point (the point rearranged by the setting) as its center.
When the auto tuning is completed, AT bias is not added and a control is executed toward the set value (SV). For details on
the auto tuning function, refer to the following:
Page 38 Auto Tuning Function
Ex.
When a negative value has been set for AT bias (reverse action)
Temperature process value (PV)
Set value (SV)
AT point
(1) 'CH1 AT bias' (Un\G546)
■Buffer memory address
The following shows the buffer memory address of this area.
Buffer memory area name
CH AT bias
CH AT bias (in the Q compatible mode)
■Setting range
The setting range is (-(Full scale)) to Full scale. The setting range depends on the setting of 'CH1 Input range' (Un\G501).
Ex.
When the following values have been set in the buffer memory area:
• 'CH1 Input range' (Un\G501): 38 (Temperature measuring range: -200.0 to 400.0, resolution: 0.1)
The setting range is -6000 to 6000.
■Setting unit
The value to be set differs depending on the value stored in 'CH1 Decimal point position' (Un\G400).
• No decimal point (0): Set a value in increments of 1 ( or digit).
• First decimal place (1): Set a value (the value multiplied by 10) in increments of 0.1 ().
■Default value
The default value is 0.
■Precautions
For 'CH1 AT bias' (Un\G546), set a range in which a PID operation fluctuates slightly and control results get no effect.
Depending on the controlled object used, accurate PID constants may not be obtained.
APPX
296
Appendix 3 Buffer Memory Areas
(1)
Time
CH1 CH2
546 746
53 85
CH3 CH4
946 1146
117 149