Selecting The Control Method - Omron EJ1 User Manual

Setting Control Specifications
4-3-2

Selecting the Control Method

Note
ON/OFF Control
Note
The control method can be set to either 2-PID control or ON/OFF control.
Variable type
E5/A5
Conditions for use
This parameter can be set only when operation is stopped.
In ON/OFF control, the control output turns OFF when the currently controlled
temperature reaches a preset set point. When the manipulated variable turns
OFF, the temperature begins to fall and the control output is turned ON again.
This operation is repeated at a certain level. The Hysteresis (Heating) param-
eter determines how much the temperature must fall before the control output
is turned ON again. Also, the Direct/Reverse Operation parameter determines
whether the manipulated variable is increased or decreased in response to an
increase or decrease in the process value.
■ Hysteresis
ON/OFF control incorporates a hysteresis setting to stabilize operation when
switching ON and OFF. The width of the hysteresis loop determines the sensi-
tivity.
• The control output (heating) and control output (cooling) hysteresis set-
tings are made with the Hysteresis (Heating) and Hysteresis (Cooling)
parameters, respectively.
• The sensitivity of standard control (heating or cooling) is set with the Hys-
teresis (Heating) parameter, regardless of the setting of the Direct/
Reverse Operation parameter.
• The Hysteresis (Cooling) parameter is effective only when using heating/
cooling control.
Hysteresis (Heating)
ON
OFF
Set point
Heating control
Variable type
D5/95
Conditions for use
The decimal point position is determined by the sensor selection. In this case,
however, the 0 (****) decimal point position setting will be treated as setting 1
(***.*).
Parameter name
PID/OnOff (Channel)
No special conditions
ON
PV OFF
Cooling control
Parameter name
Hysteresis (Heating) (Channel) 0.1 to 999.9 EU 1.0
Hysteresis (Cooling) (Channel) 0.1 to 999.9 EU 1.0
The control method must be set to ON/OFF control.
Section 4-3
Setting range Default
0: 2-PID control 0
1: ON/OFF control
Hysteresis (Cooling)
PV
Set point
Setting range Default
65