Performing On/Off Control; On/Off Control - Omron E5AR-T User Manual

4.9 Performing ON/OFF Control

ON/OFF control consists of setting an SP and then having the control output turn OFF when the temper-
ature reaches the SP during control. When the control output turns OFF, the temperature begins to fall,
and once it falls to a certain point, the control output turns ON again. This action is repeated around a
certain position. ON/OFF control requires setting the Hysteresis (Heating) parameter to the temperature
drop from the SP where control output should turn ON. The Direct/Reverse Operation parameter is used
to determine whether the MV is increased or decreased with respect to an increase or decrease of the PV.

■ ON/OFF Control

● Hysteresis
● Three-position
Control
• On the E5AR-T/ER-T, switching between advanced PID control and
ON/OFF control is accomplished by setting the Proportional Band
parameter. When the proportional band is set to 0.00, ON/OFF
control is performed, and when it is set to any value except 0.00,
advanced PID control is performed. The default setting is 10.00.
• In ON/OFF control, hysteresis is added when switching between ON
and OFF to stabilize operation. The width of the hysteresis is called
simply the hysteresis. The hysteresis is set for both heating and
cooling control output using the Hysteresis (Heating) and Hysteresis
(Cooling) parameters.
• For standard control (heating or cooling control), only the Hysteresis
(Heating) parameter is used, regardless of whether heating or
cooling is being performed.
ON
OFF
• For heating/cooling control, an area can be set where the MV is 0 for
both heating and cooling. This area is called the dead band. This
means that 3-position control can be performed.
Hysteresis (Heating)
ON
Heating
OFF

4.9 Performing ON/OFF Control

Hysteresis (Heating)
PV
SP
Dead band
Hysteresis (Cooling)
Cooling
SP
PV
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