VEGA VEGAPULS 56 Profibus PA User Manual

Page 69

VEGAPULS 56 Profibus PA

Ampl.:

XX dB

S-N:

XX dB

Lin.
curve

Linear

Integra
tion
time

0 s

Adjust-
ment

Signal
condit-
ioning

Scal-
ing

• Confirm with "

OK“.

If necessary, choose a decimal point. How-
ever, note that only max. 4 digits can be
displayed. In the menu "

prop. to“ you choose

the physical quantity (mass, volume, dis-
tance…) and in the menu "

Unit“ the physical

unit (kg, l, ft

, gal, m

…).

Linearisation:

A linear correlation between the percentage
value of the product distance and percent-
age value of the filling volume is preset. With
the menu "Lin. curve“ you can choose be-
tween linear, spherical tank and cylindrical
tank. The generation of a customized
linearisation curve is only possible with the
PC and the adjustment program VVO.

6. Meas. conditions

(see menu schematic)

7. False echo storage

A false echo storage is always useful when
unavoidable false echo sources (e.g. struts)
must be minimised. By creating a false echo
storage, you authorise the sensor electronics
to record the false echoes and save them in
an internal database. The sensor electronics
treats these (false) echoes differently from
the useful echoes and filters them out.

8. Signal-Noise difference

In the menu

you get important information on the signal
quality of the product echo. The higher the
"S-N“ value, the more reliable the measure-
ment (menu plan MINICOM).

Ampl.:

means amplitude of the level echo in
dB (useful level)

S-N:

means Signal-Noise, i.e. the useful
level minus the level of the back-
ground noise

The bigger the "S-N“ value (difference be-
tween the amplitudes of the useful signal level
and the noise level), the better the measure-
ment:
> 50 dB

Measurement excellent

40 … 50 dB

Measurement very good

20 … 40 dB

Measurement good

10 … 20 dB

Measurement satisfactory

5 … 10 dB

Measurement sufficient

< 5 dB

Measurement poor

Example:

Ampl. = 68 dB
S-N = 53 dB

68 dB – 53 dB = 15 dB

This means that the noise level is only
68 dB – 53 dB = 15 dB.

A 15 dB noise level with a 53 dB higher signal
level would ensure a high degree of meas-
urement reliability.

9. Outputs

Under the menu "Outputs“ you determine, for
example, if the current output should be
inverted, or which unit of measurement
should be shown on the sensor display.

Setup