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3.4 Input Calibration
A 10-bit A/D converter is connected to the IN1 and IN2 input terminals, which converts
the measured value to a number ranging between 0 and 1023. Practically, the 0 - 1020
range is used; the remaining three steps are used for overvoltage detection.
The purpose of calibration is to compensate the inaccuracy of components and external
factors and to ensure that the 960 value of the A/D converter matches exactly 10V in
each input. The value usually oscillates slightly around this point. Let us give an
example: suppose you place two terminals next to each other under identical external
conditions. One terminal will measure 966 and the other 957 for 10V. Calibrate the
input to eliminate such inconsistency.
Note
Keep in mind that an uncalibrated input is not non-functional. It is
able to measure and read values less precisely, but sufficiently for
rough voltage or current detection.
For calibration, use the terminals and AT commands described in
, or the
Subs. 4.2
Terminal Config tool - refer to
- for setting and application details. The following
S. 6
figure shows the calibration diagram and basic principle. The meaning of the curves are
explained below.
Figure:
Calibration Diagram
