VEGA VEGAPULS 45 VBUS - Manual (Page 57)

VEGAPULS 42, 44 and 45 – VBUS 57
Adjustment with the PC on the signal conditioning instrument
The user-programmable linearisation curve is
generated by index markers. Each index
marker consists of one value pair. A value
pair is generated from a value "
Linearised"
and a value " Percentage value". "Percentage
value" represents the percentage value of the
level. "
Linearised" represents the percentage
of vessel volume at a certain percentage
value of the level.
In the field " Transfer measured value" the
current level as percent of the adjusted span
is displayed. The measuring span has al-
ready been adjusted with the min./max. ad-
justment. In our example, the measuring
span is 4.58 m and is the range from 5.85 m
(empty) up to 1.27 m (full), see the following
illustration.
5.85 m meas. distance corresponds to 0 %
level. 1.27 m meas. distance corresponds to
100 % level. The measuring span is therefore
4.58 m (5.85 m – 1.27 m = 4.58 m).
The percentage value of 95.79 % means that
now 4.387 m of the adjusted measuring
span (4.58 m) have been reached:
4.58 • 0.9579 = 4.387 m.
0 m
100 % at 1.27 m
1,463 m (95,79 %)
Span
4.58 m
(100 %)
4.387 m
(95.79 %)
0 % at 5.85 m
The distance (product distance) outputted
by the sensor, in case you have chosen
"
distance" as output parameter, is then:
5.85 – (4.58 • 0.9579) = 1.463 m.
If the index markers or value pairs of your
vessel are not known, you have to define the
linearisation curve by incremental filling or
calculate it with the vessel calculation pro-
gram of VVO.
Defining the linearisation curve by incre-
mental filling
In the characteristics of the example, you see
four index markers or value pairs. There is
always a linear interpolation between the
index markers. The example vessel consists
of three cylindrical segments of different
height and diameter. The middle segment
has a considerably smaller diameter.
• Click the check box
"Show scaled values",
to have the selected measuring unit dis-
played on the y-axis (bottom left in the
menu window).
Index marker 1 is at 0 % filling ( percentage
value [%]), corresponding in the example to
an actual distance to the product surface of
5.850 m (empty vessel). The volume quantity
is 45 liters (fluid remaining in the vessel).
Index marker 2 is at a filling level of 30 %
(30 % of the meas. distance of
1.270 m … 5.850 m). At a filling level of 30 %,
there are 576 liters in the vessel (in our exam-
ple).