Properties Of The Profibus Pa - Siemens SIPAN 32 Instructions De Service

Mise en service et fonctionnement
4.8.2

Properties of the Profibus PA

PLS, PC
Figure 4-8 PROFIBUS PA architecture
4-38
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In addition to cyclic operation, one or more class 2 masters have
acyclic access to the field devices. Further informtion can be obtained
from the devices or settings made in the devices with this type of
communication.
A special parameterization software, e.g. SIMATIC PDM is available for
the acyclic operation.
The PROFIBUS PA enables bidirectional communication of a bus
master with the field devices via a shielded two--wire line. At the same
time the two--wire field devices are supplied via the same lines (current
J in figure 4-7).
In addition to the EN standard 50170, the PNO (PROFIBUS User
Organization) has the functions of the individual field device types
defined in a so--called profile description. These profiles determine the
minimum functional requirements and optional extensions. The
device--internal "Device Management" supplies all the necessary basic
information to the configuration tool of the control system for finding the
profile parameters. In this way, a suitable parameterization tool (e.g.
SIMATIC PDM) can operate all devices which are in conformance with
the profile, irrespective of the type and manufacturer. SIPAN 32
analyzers have the "Test Seal of Approval for Analyzers" passed by the
PNO.
The system must be implemented by one or more PROFIBUS PA
channels depending on the automation task and the number of field
devices and necessary timing behavior. A PROFIBUS PA channel
consists of the components shown in figure 4--8.
Control stand
PROFIBUS DP
Coupler
Link
T
Power
supply
Field
PROFIBUS PA
FD FD
stub cable
Dispositif de mesure de conductivité SIPAN 32
T
additional
line termination
FD = field device
C79000-B5477-C045-02