Operating functions via HART
7.18 Current sensor trim
SITRANS P300 with HART communication
7-24
Operating Instructions, 06/2005, A5E00359579-02
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Figure 7-12 Sensor trim
A
Output curve
B
Characteristic curve after lower sensor trim
C
Characteristic curve after upper sensor trim
7.18
Current sensor trim
Description
The current that is output by the transmitter can be trimmed independently of the pressure
measuring circuit. This function is designed for compensating inaccuracies in the processing
chain following the transmitter.
Example of an application
The current is to be measured as a voltage drop from 1 to 5 V at a resistance of 250 Ohm +/-
5%. To trim the tolerance of the resistance, set the current sensor so that the voltage drop at
4 mA is exactly 1 V and at 20 mA is exactly 5 V.
1. Trim at 4 mA:
Use the current sensor trim menu option to instruct the transmitter to output 4 mA. Read
the measured value from the ammeter and enter it, via SIMATIC PDM for example. The
transmitter uses this value for offset correction of the current.
2. Trim at 20 mA:
Use the current sensor trim menu option to instruct the transmitter to output 20 mA. Read
the measured value from the ammeter and enter it, via SIMATIC PDM for example. The
