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4 Calibration with FOUNDATION
™
Fieldbus Volume 7
4.2 Operation Modes for Calibration
Once the basic configuration has been completed, you may start
with the calibration. Three alternative modes of calibration are pos-
sible:
•Two-point calibration
• One-point calibration
• Multi-point calibration
Two-point calibration Two-point calibration is the most frequently used calibration
method.
Measure the lower and upper calibration point by reading in the
count rate.
One-point calibration Use this operation mode only if the upper calibration point cannot
be measured.
With this type of calibration inaccurate results may be obtained in
the upper measuring range, since the maximum measuring range
is calculated and not measured. It may happen that upon reaching
the maximum filling level the maximum measuring range (typically
100%) is indicated too early or not at all.
Measure the lower calibration point by reading in the count rate
and have the evaluation unit calculate the upper calibration point.
Enter the vessel diameter and the product density.
Multi-point calibration For tanks that require linearization, e.g. for rod detectors. Multi-
point calibration can have between 2 and 10 calibration points. All
calibration points are connected by a straight line. Therefore, this
calibration curve is also referred to as “Polygon line”.
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