VEGA FIELDBARRIER - Manual (Page 17)

FieldBarrier
Subject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
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08/
2007 122329
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5.2.3 Topologies
Fieldbus topologies are independent of whether an H1 fieldbus segment of the
FOUNDATION fieldbus or a PROFIBUS MBP segment is being operated.
The basic layout of a fieldbus with FieldBarriers is illustrated in Figure 5.1.
Two cable types with the following components are essentially recommended for both
fieldbus systems:
The use of FieldBarriers influences possible topologies. For more
detailed information, please refer to chapter 6.2.
Type A Type B
Cable structure twisted wire
pair, shielded
One or more twisted
pairs, total shielding
Conductor cross-section (nominal) 0.8 mm²
(AWG 18)
0.32 mm² (AWG 22)
Loop resistor (direct current) 44
Ω/km
112
Ω/km
Wave resistance at 31.25 kHz 100
Ω + 20%
100
Ω + 30%
Wave attenuation at 39 kHz 3 dB/km 5 dB/km
Capacitive asymmetry 2 nF/km 2 nF/km
Group runtime distortion (7.9 ... 39) kHz 1.7 µs a
a. not specified
Covering level of the shield 90% a
Maximum extent of the network for non-
intrinsically safe applications
1900 m 1200 m
Maximum extent of the network for intrinsi-
cally safe applications
1000 m a
Segment coupler
PROFIBUS MBP(-IS)
Bus termination
resistor
PROFIBUS DP
or
Power repeater
or H1 bus of the
FOUNDATION
fieldbus
or H1 bus (IS) of the
FOUNDATION
fieldbus
Spur
Spur
Spur
Trunk