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Chapter 7. PARAMETER SETUP
7-11
● O T L (MV change limit)
The MV is increased or decreased by the same value so that the output change is taken as
the limit setting value when the output change (%) after PID operation is greater than this
limit setting.
The following example shows the actual change in MV when the MV changes from 20%
to 22% with the change limit setting at 0.5%. MV is output at 0.5% setting value incre-
ments every 0.1s, and reaches 22% in 0.4s.
%
22
21
20
t t + 0.1 t + 0.2 t + 0.3 t + 0.4
s
● I O U t (PID operation initial MV)
PID operation is started in the following cases using the I O U t setting value:
• When the mode changes from READY AUTO to RUN AUTO
• When the power is turned ON in the RUN AUTO (or HOLD, FAST, END AUTO)
mode
• At completion of auto-tuning
As the PV, SP and PID parameters settings bear a relation to PID operation, the first MV
resulting from PID operation will not necessarily match the I O U t setting value.
● R P I D (PID operation initialization)
When SP changes suddenly by ADV (advance) operation, rate action in PID operation
may cause the MV in the operation to change excessively. For this reason, excessive
changes can be suppressed by initializing PID operation.
However, as initialization of PID operation may result in lost continuity, initialization
may adversely influence PID operation depending on the circumstances in which the
controller is being used.
Initialization ON/OFF and conditions can be selected by the R P I D setting.