SIEMENS
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Siemens IK PI · 2015
PROFIBUS
Electrical networks (PROFIBUS PA)
Introduction
3
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Design
Basic PROFIBUS PA design versions when
using the PA link as the PA router
Basic PROFIBUS PA design versions are shown at this point.
The PA link is used as the PA router in these configuration
examples.
However, the PA router can only be implemented per DP/PA
coupler. The PROFIBUS DP connection is then directly on the
coupler instead of per interface module.
The number of PROFIBUS PA devices is limited according to the
specifications in section "Technical data".
Line architecture with single coupler
Max. 5 PROFIBUS PA lines (line segments) can be operated
via single couplers (max. 3 for mixed configurations with ring or
coupler redundancy) on a PA link as PA router, equipped with up
to 5 DP/PA couplers.
In the line architecture with individual couplers, each line
segment is connected to one DP/PA coupler of the PA router.
The PA router can be connected to a single or redundant
PROFIBUS DP.
The FDC 157-0 the first choice as the DP/PA coupler. When
using this coupler, the PA devices can be integrated into the line
segment via active field distributors AFD4 and AFD8 (approval
for Ex zone 2/22) and AFDiS (approval for Ex zone 1/21). The PA
devices are connected to these field distributors via short-
circuit-proof spur lines.
Up to 8 field distributors of type AFD4/AFD8, 5 field distributors
of type AFDiS, or 5 field distributors of both AFDiS and AFD4/
AFD8 types combined can be optionally operated in a line
segment. The last field distributor at the end of the line leading
away from the DP/PA coupler automatically activates its bus
terminating resistor.
Intrinsically-safe PA devices in hazardous areas in accordance
with Ex zone 1/21 or 0/20 are primarily integrated into a bus
segment by means of active field distributors AFDiS. For PA
devices in Ex zone 1/21, the connection via a line segment on
the PA router with DP/PA coupler Ex [i] is a possible alternative.
The devices are integrated separately into the line segment via
SplitConnect Taps (via spur line or directly via SplitConnect M12
outlet). A SplitConnect terminator is required for the bus termina-
tion of the segment.
By grouping individual devices in different line segments,
Flexible Modular Redundancy is possible at device level.
Line architecture with redundant coupler
The PA link operable as a PA router on a single or redundant
PROFIBUS DP can only be equipped with one redundant DP/PA
coupler pair (up to 3 single couplers can also be optionally con-
figured). The redundant DP/PA coupler pair can be used either
for a line architecture with Active Field Splitter (AFS) or for a ring
architecture.
With a line architecture, the AFS is connected to the redundant
DP/PA coupler pair (2 x FDC 157-0) in the PA router. It connects
the line segment connected to it to the active of the two redun-
dant DP/PA couplers. A DP/PA coupler can be replaced without
interrupting the ongoing operation.
The PA devices are integrated in the line segment as for a line
architecture with single couplers via active field distributors
AFD4, AFD8 or AFDiS. The limits with respect to the number of
field distributors are also identical (up to 8 AFD4/AFD8, up to
5 AFDiS or up to 5 AFDiS and AFD4/AFD8 in any combination).
G_PCS7_XX_00146
SIMATIC PCS 7
automation system
PA link
PA link
PA link
PA link
AFS
AFD
AFD
AFD
AFD
PROFIBUS PA
PROFIBUS PA
AFD
AFD
PROFIBUS PA
PROFIBUS PA
PROFIBUS DP
AFDiS
AFDiS
AFDiS
© Siemens AG 2014