At Bias - Mitsubishi Electric MELSEC FX2N-2LC User Manual

FX2N-2LC Temperature Control Block
2) When either of the following conditions are given during auto tuning, the operation is
aborted.
- When the input value (PV) becomes abnormal caused by disconnection, etc.
- When the set value (SV) is changed
- When control is stopped, when the operation mode is changed or when the auto/manual
mode is set to "manual"
- When the AT bias setting is changed
- When the PV bias setting is changed
- When the digital filter setting is changed
- When the output limiter setting is changed
- When the power is interrupted
- When the AT execution command (CH1: BFM #20, CH2: BFM #29) is set to "0 (AT stop)"
Temperature
set value (SV)
5.3.2

AT bias

Set the AT bias to perform auto tuning in which the measured value (PV) should not exceed the
temperature set value (SV).
The auto tuning function performs two-position control using the temperature 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. Set the AT bias for such a
case. When the AT bias is set, the set value (SV) (AT point) with which auto tuning is per-
formed can be changed.
Measured value (PV)
Temperature
set value (SV)
AT point
Measured value (PV)
(Example: When AT is performed while the temperature is rising)
AT starts.
Example: When the AT bias is set to "-"
AT starts.
AT finishes.
AT bias
AT finishes.
Introduction of Functions 5
Time
Time
5-5
5