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3 CALIBRATION
Calibration Methods
The first step in the calibration process is to decide which calibration method will be used.
There are two different calibration methods available. Choice of calibration method depends
on the process being monitored.
The first method involves a simple two-point calibration and is useful for linear process vari-
ables. Two points are calibrated: one at Zero and one at Full Scale. The process variable is
assumed to be linear (straight line) between these two points.
The second method involves calibration at a number of points and performs linear interpola-
tion between these points. This method of calibration is useful for nonlinear process variables.
As few as three or as many as 50 points may be entered and calibrated.
The two different methods of calibration are illustrated graphically below:
Linear Calibration
Nonlinear Calibration
Zero
Fullscale
Pt 1
Pt 2
Pt 3
Non-linear calibration, using the
TABLE
function, must be activated at the factory. Adjust-
ment of the calibration points is described in Section 3.2.
