
7.5 Blind setting of zero point and limit point
● The start of scale value and the full scale value can be set without creating a reference
pressure.
● Both values can be selected as any point within the sensor limits.
● The maximum downscaling is 1:100, depending on the series and the measuring range.
7.6 Zero point calibration (position correction)
Description
A zero point calibration is used to correct a zero point error resulting from the installation
position.
Procedure
● Pressurize the device or evacuate it (at absolute pressure, < 0.1 ‰ of the measuring span).
● Perform the zero point calibration using SIMATIC PDM or the HART Communicator.
● If you do not have a vacuum, perform a trimming of the lower sensor calibration point at a
known reference pressure.
CAUTION
For absolute pressure transmitters, the zero point is at vacuum. A zero point calibration
with a pressurized transmitter will lead to faulty settings!
Note
The effective measuring range is reduced by the amount of the upstream pressure.
Example:
With an upstream pressure of 100 mbar, the effective measuring range of a 1-bar
transmitter is reduced to a point between 0 and 0.9 bar.
See also
Trimming the sensor (Page 124)
Operating functions through HART
7.6 Zero point calibration (position correction)
SITRANS P, DS III series with HART
Operating Instructions, 09/2012, A5E00047092-08 117
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