WIKA A-IAI-1 - Handbuch (Seite 17)

GB
WIKA operating instructions attachable indicator model A-AI-1 17
2018357.06 08/2012 GB/D
Offset and slope correction
The offset and slope correction is used to compensate for sensor tolerances
and for the fine adjustment of deviations of the transmitter or signal trans-
ducer.
To set the offset and slope correction, carry out the following:
■ While the actual value is being displayed, press key 3 for 2 seconds, until
"oFFS" appears in the display.
■ To set the parameter values, press keys 2 and 3.
■ To save the set value, press key 1. The parameter name will then appear in
the display once more.
■ To get to the next parameter to change, press key 1. The name of the
parameter will appear in the display.
Parameters Values Description
Key 1 Keys 2 and 3
oFFS Zero offset (offset)
-5.00 … 5.00 The input of the offset is made in digits. The set
offset value is subtracted from the measured value.
ScAL Slope (scale)
-5.00 … 5.00 The input of the slope correction factor is made
in %. The displayed value is calculated as per the
following equation:
Display = (measured value - Offset - di.Lo) * (1 +
slope correction [% / 100] ) + di.Lo
Example for offset and slope correction
Connection of a pressure transmitter
The instrument display without offset and slope correction is as follows:
at 0 bar = 0.08, at 20 bar = 20.02
From this is calculated:
Zero point: 0.08
Slope: 20.02 – 0.08 = 19.94
Deviation: 0.06 = set slope - actual slope = 20.00 – 19.94
Therefore the following should be set:
Offset = 0.08 = zero error
Scale = 0.30 = deviation/actual slope = 0.06 /19.94 = 0.0030 = 0.30 %
6. Commissioning, operation