Watlow Series F4S/D - Manual (Page 66)

Inputs/Outputs
Calibration Offset
Calibration offset allows a device to compensate for
an inaccurate sensor, lead resistance or other fac-
tors that affect the input value. A positive offset in-
creases the input value, and a negative offset de-
creases the input value.
You can view or change the offset value of inputs 1,
2 or 3 with the Calibration Offset parameter.
Location in software: Setup Page > Analog Input x
(1 to 3).
Figure 6.2a — Calibration Offset.
Time
Temperature
Temperature Reading
from Sensor
Actual Process Temperature
The negative calibration offset will
compensate for the difference
between the sensor reading and
the actual temperature.
Filter Time Constant
A time filter smooths an input signal by applying a
first-order filter time constant to the signal. Either
the displayed value or both the displayed and con-
trol values can be filtered. Filtering the displayed
value makes it easier to monitor. Filtering the sig-
nal may improve the performance of PID control in
a noisy or very dynamic system.
A positive value affects only the viewed values. A
negative value affects both the viewed and control
values.
Location in software: Setup Page > Analog Inputs x
(1 to 3).
Figure 6.2b — Filtered and Unfiltered Input Signals.
Unfiltered Input Signal
Time
Temperature
Filtered Input Signal
Time
Te
mperature
6 . 2 ■ F e a t u r e s Wa t l o w S e r i e s F 4 S / D
Open Loop Detect
Open loop checks the integrity of the control loop, consisting of the controller output, power control, heater
and sensor.
If the output power is at its maximum for a period of time equal to the reset time and the input has not
changed at least ± 5°F, the controller will switch to Manual Mode at 0% output power . The upper screen will
display [oPLP`] and the lower screen will display “Open Loop.”
To clear an open loop error, after correcting the problem that caused it, turn the controller off then back on.
Location in software: Setup Page > System.