Zero correction
The "Zero Correction" (V9H5) parameter offers a further possibility of carrying out position
calibration. Besides the display value, and in contrast to position calibration using bias
pressure (V0H5/V0H6), the current value is balanced with the on-site display (measured
value (V0H0)).
When carrying out a zero correction, an applied pressure is assigned a correction value
using "Zero Correction" (V9H5). This shifts the sensor characteristics curve according to
the diagram and the "Low Sensor Trim" (V7H4) and "High Sensor Trim" (V7H5) values are
recalculated. The "Zero Correction Value" (V9H6) matrix field indicates the value by which
the sensor characteristic curve was shifted.
The "Zero Correction Value" (V9H6) is calculated as follows:
•
"Zero Correction Value" (V9H6) =
"Sensor Pressure" (V7H8) – "Zero Correction" (V9H5)
The "Sensor Pressure" (V7H8) indicates the effective applied pressure.
#
Matrix Path through the
menus
Entry
1
Display "Measured Value" (V0H0) = 0.03 bar
(position-dependent pressure)
Display "Current (V7H0) = 4.03 mA
The 4 mA Value (V0H1) is set to 0.0 bar.
2
The pressure for zero correction is:
"Sensor Pressure" (V7H8) = 0.03 bar
(corresponds to the position-dependent
pressure)
Main group: Service
3
The value 0.0 is assigned to the applied
pressure.
V9H5
➤
Zero
correction
0.0
Confirm
4
After making inputs into the "Zero Correction"
(V9H5) parameter, the parameters adopt the
following values:
–
"Zero Correction Value" (V9H6):
V9H6 = V7H8 – V9H5
V9H6 = 0.03 bar – 0.0 bar
V9H6 = 0.03 bar
–
"Measured Value" (V0H0) = 0.0 bar
–
"Current" (V7H0) = 4.00 mA
4 mA level
The current signal is set to 3.8…20.5 mA as standard when operating correctly. When
selecting the 4 mA level, it is ensured that a minimum current signal does not fall below
4 mA.
The following applies:
•
OFF: lower current level of 3.8 mA
•
ON: lower current level of 4 mA
#
Matrix Path through the
menus
Entry
Main group: Additional functions
V7H3
➤
Current output
min. 4 mA
e.g. ON
Confirm
{
0.03
1
0
1.03
BA1
87Y1
1
Sensor
characteristic curve
pressure
e. g. [bar]
Zero
correction
value
(V9H6)
Low Sensor
Trim (V7H4)
High Sensor
Trim (V7H5)
after
zero
correction
before
zero
correction
Cerabar S
5 Pressure Measurement
Hauser
23
