BA_080_en_2022-01_11.02 Pressure transmitter PASCAL CV4
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6.4.3.3
Upper and lower adjustment
The lower adjustment results in an offset of the characteristic curve. It thus affects zero and
span of the measuring range.
The upper adjustment changes the slope of the characteristic curve by correcting the span
of the measuring range.
Execute the lower adjustment prior to the upper adjustment for a correct full adjustment.
Figure 8: Effect of the upper and lower adjustment on the characteristic curve
You can perform the upper and lower adjustment at any reference pressure level. For in-
stance, you can perform the lower adjustment of a -
1…4 bar rel device at -900 mbar rel. The
reference pressure level for the upper offset can also be freely chosen. To ensure that the
adjustment is as precise as possible, the upper and lower adjustment should be performed
as close as possible to the lower range value and upper range value of the measurement
ranges.
6.4.3.4
Current adjustment
You can use the current adjustment, if the reading at the end of the measurement chain (re-
converted current value) does not correspond to the measured pressure. With this function
you can compensate deviations in the output stage as well as the downstream measurement
chain.
Proceed as follows (example for 4 mA):
Select function "Current adjust."
–> "Adjust. 4 mA"
Use "OK" to activate constant current mode (4 mA). CAUTION! The output current
value now no longer corresponds with the measured value! This is indicated by the
icon "Function check" (see 6.2.3).
Read the displayed current value at the end of the measurement chain.
Enter this current value (e.g. 3.996) at the device. The device now corrects the current
output so that 4 mA are shown at the end of the measurement chain.
When leaving the function, the constant current mode is disabled and the current value cor-
responds again to the measured value.
