See also
Application [05] (Page 110)
9.3.6
Sensor calibration
You use the sensor calibration to set the characteristic curve of the device at two trim points.
The results are then correct measured values at the sensor trim points.
The sensor trim points can be selected as any points within the nominal range.
Devices that are not turned down prior to delivery are trimmed at 0 bar and the high limit of the
nominal range.
Devices that are turned down prior to delivery are trimmed at the low and high limits of the set
measuring range.
Examples
● For a particular device that is not turned down (e.g. 63 bar), the typical measured value is
50 bar. To attain the highest possible accuracy for this value, set the upper sensor trim at
50 bar.
● A 63-bar pressure transmitter is turned down to 4 to 7 bar. You can attain the highest
possible accuracy by selecting 4 bar for the low trim point and 7 bar for the high trim point.
● A 250-mbar absolute pressure transmitter shows 25 mbar at 20 mbar. A reference pressure
of 20 mbar is available. To correct the zero point, perform a sensor trim at the lower trim point
with 20 mbar.
Note
Use a test device whose accuracy is at least three times as high as the accuracy of the
pressure transmitter.
Sensor calibration at the low calibration point
1. Use remote control (e.g. SIMATIC PDM) to select the menu command "Device > Sensor
calibration".
2.
Apply the pressure for the low calibration point at the device.
3. Apply the pressure value that you have created and assign the pressure value to the device.
The device applies the set value.
The device carries out an offset correction of the characteristic curve.
Parameter assignment
9.3 Parameter assignment over remote operation
SITRANS P320/P420 with 4 to 20 mA/HART
Operating Instructions, 11/2019, A5E44852162-AC 151
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