Omron EJ1 User Manual page 91

Setting Control Specifications
2-PID Control (Two-
degrees-of-freedom
PID)
Note
66
■ Three-position Control
In heating/cooling control, a dead band area can be set where the MV is 0%
for both heating and cooling. with a dead band, 3-position control can be
achieved.
Hysteresis (Heating)
ON
Heating side
OFF
The proportional band (P), integral time (I), and derivative time (D) must be
set for 2-PID control.
■ PID Settings
When the control characteristics are unknown, perform autotuning (AT) or
self-tuning (ST with
mum PID constants for the set point at that time are set automatically.
When the control characteristics are already known, the PID parameters can
be set directly to adjust control. The PID parameters are set with the Propor-
tional Band (P), Integral Time (I), and Derivative Time (D) parameters.
Note Refer to 4-3-8 Tuning for details on autotuning or self-tuning (ST
with
V1.2
Variable type
D0/90
Conditions for use
(1) Refer to 4-7-1 Bank Function for details on banks.
(2) The decimal point position is determined by the sensor selection. In this
case, however, the 0 (****) decimal point position setting will be treated as
setting 1 (***.*).
• Proportional action: In proportional action, the MV is proportional to the
• Integral action:
Dead band
Set point
). When AT (or ST with
V1.2
).
Parameter name
Proportional Band (BANK) 0.1 to 999.9 EU
Integral Time (BANK) 0 to 3999 Seconds
Derivative Time (BANK) 0.0 to 999.9 Seconds
The control method must be set to 2-PID control.
deviation (control error).
This control action produces an output that is propor-
tional to the time integral of the control error. An off-
set normally occurs in proportional control, so
proportional action is used in combination with inte-
gral action. As time passes, this offset disappears
and the control temperature (process value) matches
the set point.
Section 4-3
Hysteresis (Cooling)
Cooling side
PV
) is executed, the opti-
V1.2
Setting range Default
8.0
(See note 1.)
233
40.0