Watlow Series F4P - Manual (Page 60)

Inputs
Multiple Input Offsets
Offset point are used to compensate for differences be-
tween the target process value and the sensor value read
by the Series F4P. Multiple offset points enable the F4P
to compensate for non-linear differences between the sen-
sor readings and target process values over the thermal
or process system operating range. Sensor reading differ-
ences can be caused by sensor placement, tolerances, an
inaccurate sensor or lead resistance.
The Series F4P controller supports both single point and
multiple point offsets. The choice for single or multiple
offsets is made in the Setup Page > Analog Input Menu.
A single point offset allows the F4P to control the process
to one offset value difference linearly either above or be-
low the sensed value over the entire operating range.
Multiple point offsets allow the Series F4P to control the
process to 10 different offset points over the operating
range. Each offset point has a programmable positive or
negative offset value. Offset points can be positioned any-
where over the operating range. Offset point values are
programmable between -1,000 and +1,000. Offset values
are linearly interpolated between the nearest two offset
points. Offset values are added to the sensed value to es-
tablish a target process value. Offset Point 1 is pro-
grammable as the first point or low end point of the
range. Offset points 2 through 10 follow sequentially. Off-
set values lower than the first point (point 1) or higher
than the last point (point 10) are zero.
Location in software: Setup Page > Analog Input x (1 to
3) Menu > Input Offset x (1 to 10).
Figure 7.2 — Multiple Input Offsets.
Time
Te
mperature
Reading from Sensor
with Offset
(Displayed Value)
Reading from Sensor
without Offset
(Actual Value)
Offset 10
Value
Offset 1
Value
No Offset
Offset 2
3
4
5
6 7
8
9
Offset Zone
7 . 2 ■ F e a t u r e s Wa t l o w S e r i e s F 4 P