Instruction manual

SITRANS TW
104 A5E00054075-05
Functions / Operation by HART
4.2.12 Sensor adjustment
With the sensor adjustment it is possible to set the characteristic of the sensor at two
adjustment points. The results are then correct measured values at the adjustment
points. The error percentage on the basis of the characteristic can be reduced by
adjusting the sensor.
4.2.12.1 Trimming the lower sensor adjustment point
The process variable (e.g. temperature or resistance) at which the lower sensor-
adjustment is made, is applied to the transmitter input. With SIMATIC PDM or the
HART Communicator you instruct the transmitter to accept this process value. This
represents an offset shift of the characteristic (B, figure 12, page 104).
4.2.12.2 Trimming the upper sensor adjustment point
The process variable (e.g. temperature or resistance) at which the upper sensor
adjustment is made, is applied to the transmitter input. With SIMATIC PDM or the
HART Communicator you instruct the transmitter to accept this process value. This
makes a slope correction to the characteristic (C, figure 12). The lower sensor adjust-
ment point is not affected.
Figure 12 Sensor adjustment
A: Output characteristic
B: Characteristic after lower sensor adjustment
C: Characteristic after upper sensor adjustment
measuredprocess
variable
1.: A → B: Parallel shift
2.: B
→ C: Change in slope
Lower adjustment
point
upper
adjustment point
given
process value