Filter
Top Products
272
• When it is not a problem if a certain amount of time is required for stabilization
(settlement time), but it is important not to cause overshooting, then enlarge
the proportional band.
SV
Control by measured PID
When P is enlarged
• When overshooting is not a problem but it is desirable to quickly stabilize con-
trol, then narrow the proportional band. If the proportional band is narrowed too
much, however, then hunting may occur.
When P is narrowed
Control by measured PID
SV
• When there is broad hunting, or when operation is tied up by overshooting and
undershooting, it is probably because integral operation is too strong. The
hunting will be reduced if the integral time is increased or the proportional band
is enlarged.
Control by measured PID
(when loose hunting occurs)
Enlarge I or P.
SV
• If the period is short and hunting occurs, it may be that the control system re-
sponse is quick and the derivative operation is too strong. In that case, set the
derivative operation lower.
Control by measured PID
(when hunting occurs in a short period)
Lower D.
SV
Flags ER: Content of DM word is not BCD, or the DM area boundary has been
exceeded.
A PID parameter SV is out of range.
The PID operation was executed but the cycle time was two times the
sampling period. PID(––) will be executed for this error only even when
ER (SR25503) is ON.
CY: The PID operation is being executed.
Special Math Instructions Section 5-21