CHAPTER 4 APPLIED OPERATION
E5CK
4–4
Ă• Switching between advanced PID control and ON/OFF control is carĆ
ried out by the PID/ON/OFF" parameter (expansion mode). When this
parameter is set to [ĂĂĂ
], advanced PID control is selected, and when
set to [ ], ON/OFF control is selected. Default is [ĂĂĂ ].
Ă• In ON/OFF control, hysteresis is provided in the program when switchĆ
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 hysteresis (cool)" parameters, respectively.
Ă• In standard control (heating or cooling control), hysteresis can be set
only for the heating side.
ON
OFF
PV
Hysteresis (heat)
Set point
Ă• In heating and cooling control, a dead band can be set. So, 3Ćposition conĆ
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 reset : Level 2 Manipulated variable when control
operation is stopped
MV at PV error : Level 2 Manipulated variable when control
operation is PV error
Hysteresis (heat) : Level 1 ON/OFF control
Hysteresis (cool) : Level 1 ON/OFF control
PID / ON/OFF : Expansion ON/OFF control
JON/OFF control
F Hysteresis
Parameters
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