Advanced Pid Control - Omron CQM1 Operation Manual

Application Examples
3-5-4

Advanced PID Control

If ON/OFF control is used, in the following graph hunting, the amplitude and
period of which depend on the controlled object, will occur even if the hystere-
sis of the Temperature Control Unit is adjusted. If the hunting is not within the
permissible range determined by the user, use advanced PID control.
Temperature
SP
Hysteresis
PV
100%
MV
0%
If advanced PID control (i.e., SW1-1 is turned ON) is selected, the Tempera-
ture Control Unit will operate with the P value fixed to 40.0, the I value fixed to
240, and the D value fixed to 40.
The user's required control may not be performed with the default PID param-
eters. In this case, refer to 3-6 AT (Expansion Mode) and 3-6-1 Manual Set-
tings (Expansion Mode) to set the most suitable PID parameters.
Even if the most suitable PID parameters are set, hunting may occur if the
control period is long. In this case, set SW1-6 according to the characteristics
of the controlled object. If SW1-6 is turned OFF, the control period will be 20 s
and if SW1-6 is turned ON, the control period will be 2 s.
When the control period is set to 2 s (i.e., SW1-6 is turned ON), it can be set
to 1 through 99 s freely. Refer to 3-6-1 Manual Settings (Expansion Mode) for
details.
Section 3-5
Time
281