VEGA VEGAPULS 45 Profibus PA - Manual (Page 6)

6 VEGAPULS 42, 44 and 45 – Profibus PA
24908-EN-041227
1.3 Profibus output signal
PRO PRO PRO PRO PROcess FI FI FI FI FIeld BUS BUS BUS BUS BUS (PROFIBUS) is the re-
sult of a joint project of thirteen companies
and five universities. The companies Bosch,
Klöckner-Möller and Siemens played a deci-
sive role. The specifications of the bus are
described in the protocol layers 1, 2 and 7 of
the ISO/OSI reference model and are avail-
able from the PNO (Profibus user organisa-
tion). Since layers 3 … 5 have not yet been
developed as a standard, Profibus still has a
lot of potential for future development.
Today approx. 600 companies make use of
Profibus technology and belong to the PNO.
Profibus FMS
FMS FMS FMS FMS stands for Fieldbus Messaging
Specification, Profibus DP DP DP DP DP for Decentralised
Periphery and Profibus P P P P PA A A A A for Process Auto-
mation.
As a process automation bus, Profibus PA
also enables power supply over the bus. Up
to 32 sensors can be operated on a shielded
two-wire cable that carries both power sup-
ply and measuring signal. In Ex areas, up to
ten sensors can be connected from the PA
level to one two-wire cable (EEx ia).
Bus structure
The Profibus DP and PA network consists of
up to 126 master and slave participants.
Data are always exchanged from point to
point, with the data traffic being exclusively
controlled and checked by master devices.
Communication is carried out acc. to the
Token-Passing procedure. This means that
the master holding the Token can contact the
slaves, give instructions, enquire data and
cause the slaves to receive and transmit
data. After the work is done or after a prede-
termined time interval, the Token is passed
on by the master to the next master.
1.2 Application features
Applications
• level measurement of any liquid
• measurement also in vacuum
• all slightly conductive materials and all
substances with a dielectric constant > 2.0
can be measured
• measuring range 0 … 10 m (type 42).
measuring range 0 … 20 m (type 44).
measuring range 0 … 4 m (type 45).
Two-wire technology
• power supply and output signal on one
two-wire cable
• output signal and signal processing com-
pletely digital, therefore maximum accuracy
• Profibus profile 3 sensor.
Rugged and abrasionproof
• non-contact
• high-resistance materials
Exact and reliable
• accuracy 0.05 %.
• resolution 1 mm
• unaffected by noise, vapours, dusts, gas
compositions and inert gas stratification
• unaffected by varying density and tem-
perature of the medium
• measurement in pressures up to 40 bar
and product temperatures up to 150 °C.
Communicative
• individual connection, with up to 32 sensors
on one two-wire cable (digital output signal)
on the segment coupler
• integrated measured value display
• optional display module separate from
sensor
• adjustment with detachable adjustment
module, pluggable in the sensor or in the
external display
• adjustment from the PLC level, on the sen-
sor or on the Master-Class 2 adjustment
PC.
Approvals
• CENELEC, ATEX, PTB, FM, CSA, ABS, LRS,
GL, LR, FCC.
Product description