Watlow PM PLUS™ 6 • 89 • Chapter 8: Features
Reverse bumpless ignores the transition from Off to Auto.
Time
Temperature
40%
Sensor
Break
2 minutes
Locks in
Output
Power
0%
Set Point
Actual Temperature
Output Power
Power
100%
Input Error Latching (Operations — Setup -— Analog Input — [on,off]) determines the controller’s response
once a valid input signal returns to the controller.
• If latching is on, the controller will indicate an input error until the error is cleared. To clear a latched
alarm, press the Home icon as indicated on the screen.
• If latching is off, the controller will automatically clear the input error and return to reading the temper-
ature. If the controller was in the auto mode when the input error occurred, it will resume closed-loop
control.
• If the controller was in manual mode when the error occurred, the controller will remain in open-loop
control. The Manual Control Indicator Light % is on when the controller is operating in manual mode.
On-Off Control
On-off control switches the output either full on or full off, depending on the input, set point and hysteresis
values.
The hysteresis value indicates the amount the process value must deviate from the set point to turn on the
output. Increasing the value decreases the number of times the output will cycle. Decreasing hysteresis
improves controllability. With hysteresis set to 0, the process value would stay closer to the set point, but
the output would switch on and off more frequently, and may result in the output “chattering.”
On-off control can be selected with Heat Algorithm (Operations — Setup - Control Loop - Heat Algorithm) or
Cool Algorithm (Operations — Setup - Control Loop - Cool Algorithm). Then, On/Off hysteresis can be set at
Operations — Setup - Control Loop - On/Off Heat Hyster. or Operations — Setup - Control Loop - On/Off Cool
Hyster..
Input Error failure mode does not function in on-off control mode. The output goes off.
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