4.1 Selecting the Control Method
E5CK
4--3
•
Switching between advanced PID control and ON/OFF control is car-
ried out by the “PID / ON/OFF” parameter (expansion mode). When this
parameter is set to [
], advanced PID control is selected, and when
set to [
], ON/OFF control is selected. Default is [
].
•
In ON/OFF control, hysteresis is provided in the program when switch-
ing between ON and OFF to stabilize operation. The hysteresis width
provided during ON/OFF control is simply referred to as
“
hysteresis.”
Control output (heat) and control output (cool) functions are set in the
“
hysteresis (heat)” and
“
hysterisis (cool)” parameters, respectively.
•
In standard control (heating or cooling control), hysteresis can be set
only for the heating side.
ON
OFF
PV
Hysteresis (heat)
Set point
•
In heating and cooling control, a dead band can be set. So, 3-position con-
trol is made possible.
ON
OFF
PV
Hysteresis (heat)
Heating
side
Set point
Cooling side
Hysteresis (cool)
Dead band
Symbol
Parameter Name: Mode
Description
Control output 1
assignment : Setup
For specifying control method
Control output 2
assignment : Setup
For specifying control method
Direct/Reverse
operation
: Setup
For specifying control method
Dead band
: Level 1
Heating and cooling control
Cooling coefficient
: Level 1
Heating and cooling control
MV at stop
: Level 2
Manipulated variable when control
operation is stopped
Hysteresis (heat)
: Level 1
ON/OFF control
Hysteresis (cool)
: Level 1
ON/OFF control
PID / ON/OFF
: Expansion ON/OFF control
J
ON/OFF control
F
Hysteresis
Parameters