VEGA D90 Profibus PA - Manual (Page 4)

4 Pressure transmitter D90 (Profibus PA)
Product description
1 Product description
1.1 Function and configuration
D90 pressure transmitters are efficient instru-
ments for hydrostatic level measurement. A
dry ceramic-capacitive CERTEC
® measuring
cell is used as the pressure sensor element.
The hydrostatic pressure effects a capaci-
tance change on the ceramic diaphragm.
This capacitance change is detected by an
ASIC (Application Specific Integrated Circuit)
and converted into a pressure-proportional
signal by the integrated electronic module
with microcontroller. Precise, high-resolution
digital processing of measurement data
ensures excellent technical data.
The electronics module is powered by a
Profibus DP - PA segment coupler. The
measured pressure is transmitted via the
bus cable as digital signal to the processing
system and can be displayed on the indicat-
ing module.
To improve reliability, the functionality of im-
portant electronic components is continu-
ously checked, and internal parameters such
as sensor value, temperature and operating
voltage are closely monitored.
The pressure transmitters with ceramic
CERTEC
® measuring cell offer the advantage
of continuous self-monitoring: the measuring
and reference capacitances of the measuring
cell constitute a predefined ratio over the
entire measuring range. Any deviation from
these data is a reliable indicator of a malfunc-
tion of the measuring cell. If errors or mal-
functions are detected during these routines,
fault signals are triggered according to the
Profibus PA specification.
The pressure transmitter D90 consists of two
parts, the transmitter and the processing
unit. Both parts are connected via a three-
wire screened cable (depending on the ver-
sion, with or without breather capillaries). The
processing unit contains the adjustment
elements (address switch, keys and LCD)
and the terminals for the Profibus PA cable.
Profibus PA version
The instrument profile of the pressure trans-
mitter D90 is according to the profile specifi-
cation version 3.0. The instrument master file
(GSD) is supplied with the pressure transmit-
ter D90. In addition, the GSD is available as a
download file from the VEGA homepage
(www.vega.com).
Adjustment and indication
The following adjustment versions are avail-
able:
- menu-driven adjustment (4 keys and DOT-
Matrix) in the processing unit
- via PC with the adjustment software VEGA
Visual Operating (VVO)
- optional, processing unit equipped with an
indicating module.
0 - 20 bar
Transmitter
Processing unit
Profibus PA
cable