Omron EJ1 User Manual page 88

Setting Control Specifications
Heating/Cooling
Control
Note
To perform heating/cooling control, assign the control output (cooling) function
to one of the outputs. For example, when you want to perform heating/cooling
control with channel 1, assign channel 1 control output (cooling) to one of the
outputs.
• Refer to 4-2-1 Control Output Assignments for details on assigning the
control output for cooling.
• The Cooling Coefficient and Dead Band parameters must be set for this
PID control, in addition to the Proportional Band (P), Integral Time (I), and
Derivative Time (D) parameters.
Cooling Coefficient
If the heating characteristics and cooling characteristics of the control object
are very different and good control characteristics cannot be achieved with the
same PID constants, the cooling coefficient can be used to adjust the propor-
tional band (P) for the control output assigned to cooling. Use this to achieve
balanced control between the heating side and cooling side.
The proportional bands (P) for the control outputs assigned to the heating/
cooling sides can be calculated using the following equations.
• P for the heating side = P
• P for the cooling side = P for the heating side × Cooling coefficient
The cooling P is obtained by multiplying the heating P by the cooling coeffi-
cient, so the cooling output control characteristics are different from the heat-
ing output control characteristics.
Output
Cooling P
Heating P
0
Set point
Heating P × 0.8
Variable type
D0/90 Cooling Coefficient
Conditions for use The control method must be set to heating/cooling control and
2-PID control.
Refer to 4-7-1 Bank Function for details on banks.
Dead Band
The dead band is set with the set point as its center.
Setting a negative value produces an overlap band.
Dead band:
Output
Positive dead band width
Heating
Cooling side
side
Set point
Output
Heating P
PV
0
Set point
Heating P × 1.5
Parameter name
(BANK) 0.01 to 99.99
Output
Heating
side
PV
Set point
Section 4-3
Cooling P
PV
Setting range Default
1.00
Overlap band:
Negative dead band width
Cooling side
PV
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