VEGA VEGAFLEX 52P (Profibus PA) - Manual (Page 6)

6 VEGAFLEX 51P and 52P
1.4 Profibus output signal
As a process automation bus, Profibus PA
enables power supply over the bus. Up to 32
sensors can be operated on a shielded two-
wire cable that carries both power supply
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 DP and PA bus consists of up to 126
master and slave participants. Data are al-
ways exchanged from point to point, with the
data traffic being exclusively controlled and
checked by master devices. Communication
is carried out according to the Token-Passing
procedure. This means that the master hold-
ing 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 predetermined time
interval, the token is passed on by the mas-
ter to the next master.
Master-Class 1
is the actual automation system, i.e. the proc-
ess control computer or the PLC that en-
quires and processes all measured values.
Master-Class 2
One or several Master-Class 2 can operate in
a Profibus network. As a rule, Master-Class 2
devices are engineering, adjustment or visu-
alisation stations. The VEGA adjustment soft-
ware VVO (VEGA Visual Operating) operates
as Master-Class 2 participant on the DP bus
and can work on an engineering PC, on an
adjustment PC or on the process control
computer and can access any VEGA sensor
on the PA level.
Product description
Adjustment with the PC and the standard cable
RS 232 on the VEGALOG processing system
VEGALOG 571 CPU VEGALOG 571 EA
2
1 ... 15
......
The PC with the Profibus interface card can
be connected directly at any location to the
DP bus by means of the standard RS 485-
Profibus cable.
The adjustment and parameter data can be
saved with the adjustment software on the
PC. On request, the adjustment can be also
transferred to other sensors.
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