Selecting The Control Method - Omron E5EK - MANUAL 2 User Manual

4.1 Selecting the Control Method

+ Heating and
cooling control
' Dead band
Output
Heating
side
0
' Cooling coeffi-
cient
' Manipulated vari-
able at stop
Switching with
Manual operation
4–2
When selecting the control method, set the parameters according to the
following table. (Parameters are factory set to heating control.)
Parameter
Control
Method
Heating control
(Standard)
Cooling control
(Standard)
Heating and cooling
control
For details on how to assign outputs, see 3.3 Setting Output Specifications
(page 3 7).
When heating and cooling control is selected, the deadband" and cool
ing coefficient" parameters can be used.
The dead band is set with the set point as its center. The dead band width
is the set value of the dead band" parameter (level 1 mode). Setting a posi
tive value produces a dead band, while setting a negative value produces
an overlap band. Default is set to 0.00: 0.00% FS."
Dead band: dead
band width = positive
Cooling
side
Set point
If the heating and cooling characteristics of the control target greatly dif
fer, preventing satisfactory control characteristics from being obtained by
the same PID parameters, adjust the proportional band (P at cooling side)
using the cooling coefficient to balance control between the heating and
cooling sides. In heating and cooling control, P at the heating or cooling
side is calculated by the following formula:
Heating side P = P; Cooling side P = cooling coefficient  P
In heating and cooling control, the manipulated variable output that is
output when controller operation is stopped is dependent on the set
value of the "MV at stop" parameter (level 2 mode) in the same way as
for standard control.
However, note that in heating and cooling control, the manipulated vari
able at the cooling side is treated as a negative value for the sake of conve
nience. When the manipulated variable at STOP is a negative value, the
manipulated variable is output to only the cooling side, and when a posi
tive value, the manipulated variable is output to only the heating side.
The factory setting is 0". If the controller is operated using the factory
setting, the manipulated variable is not output to both the heating and
cooling sides.
When the overlap band is set, the bumpless function that operates when switching
between manual and automatic operation may not work.
Control output 1
assignment
Control output (heat)
Control output (heat)
Control output (heat) Control output (cool)
Output
Heating
side
PV
0
Control output 2 Direct/Reverse
assignment operations
-
Reverse operation
-
Direct operation
Reverse operation
Overlap band: dead
band width = negative
Cooling
side
Set point
PV