SIEMENS
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Siemens IK PI · 2015
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Overview
(continued)
PROFIBUS
Electrical networks (PROFIBUS PA)
Active field distributors
3
Active field distributor AFDiS
Active field distributor AFDiS
The active field distributor AFDiS (Active Field Distributor intrin-
sically Safe) can be operated in environments in accordance
with Ex zone 1/21 and 2/22. It can integrate up to 6 intrinsically-
safe PA or FF field devices into a fieldbus segment (line/ring) via
its intrinsically-safe, short-circuit-proof spur line connections.
Instead of the spur line, it is also possible to use a subsegment
for 3 to 4 devices with a max. length of 500 m at connection S1
of the AFDiS. The spur lines with type of protection Ex [ia] as well
as the subsegment can be routed into Zone 0/20.
Up to 5 field distributors AFDiS with a total of up to 31 field
devices can be operated in a fieldbus segment. The limitation to
5 field distributors is also mandatory for mixed operation of AFD
and AFDiS.
The number of field devices per segment additionally depends
on the current consumption of the devices. A current of 1 A is
available for all field devices of the segment.
With the integrated repeater function, the AFDiS has the
following advantages compared to the AFD:
•
Spur line lengths are independent of the total number of spur
lines in the bus segment
•
Spur line lengths need not be be taken into account when
determining the total length of the bus segment
Under the following conditions, an AFDiS in a ring segment can
be replaced during operation without failure of the segment:
Installation in Zone 2/22 or in a non-hazardous area.
For compliance with IP66 protection, it is necessary to protect
unused spur line connections by plugs.
Active field splitter AFS
The active field splitter (AFS) connects a PA or FF line segment
with a redundant coupler pair of a PA or FF router. The AFS inter-
connects the line segment with the respective active coupler.
The PA or FF line segment can be connected to the AFS via one
or two (center feed) identical Y-connectors out of a total of 4.
For the center feed, the line segment is connected via the two
Y-connectors (bus termination switch on both FDC 157 couplers
set to "OFF").
For compliance with IP66 protection, it is necessary to protect
unused connections by plugs.
Bus
terminating
resistor 100 Ω
Subsegment max. 500 m
PA link
Ex Zone 1
Ex Zone 0
PROFIBUS DP
G_PCS7_XX_00285
AFDiS
AFDiS
AFDiS
© Siemens AG 2014