Omron C200HX Operation Manual page 290

Special Math Instructions
Flags
Example 1
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
• 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.
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.
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)
SV
Content of DM word is not BCD, or the DM area boundary has been
ER:
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.
At the rising edge of IR 00000 (OFF to ON), the work area in DM 0207 to
DM 0232 is initialized according to the parameters (shown below) set in
DM 0200 to DM 0206. After the work area has been initialized, PID control is
executed and the manipulated variable is output to IR 020.
While IR 00000 is ON, PID control is executed at the sampling period intervals
according to the parameters set in DM 0200 to DM 0206. The manipulated vari-
able is output to IR 020.
Control by measured PID
When P is enlarged
When P is narrowed
Control by measured PID
Control by measured PID
(when loose hunting occurs)
Enlarge I or P.
Lower D.
Section 5-21