Flowserve MX/QX Profibus DP/PA Field Unit - Manual (Page 21)

21
PB DPV1 / PA Field Unit Installation and Maintenance FCD LMENIM2336-03 – 12/12
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Table 2.7 – Recommended Lengths of PROFIBUS PA Spurs (Stubs)
Number of Spur
Cables
Length of Spur Cable
Intrinsically Safe (m)
Length of Spur Cable
Non-Intrinsically Safe (m)
19 to 24 30 30
15 to 18 30 60
13 to 14 30 90
1 to 12 30 120
NOTE: The maximum lengths are estimates and depend on the condition of the actual cable.
There are several topologies for PROFIBUS networks:
• Daisy Chain – A single cable daisy chained in and out of each device. End devices only have one
cable.
• Tree – Cables and electronic devices (such as repeaters or link modules) are used to branch out
from different points.
• Star – Similar to a Tree configuration but the cables all originate from one centralized point that is
comprised of electronic devices (such as repeaters or link modules).
• Combination of the above.
Figure 2.8 – PROFIBUS PA Cable Topologies
PROFIBUS
Interface
Control Highway
Distributed Control
System (Host)
Junction
Box
Tree
Daisy Chain
Bus with spurs
(or drops)
Point-to-point
Schematic topology: Details such
as terminators and power supplies
not shown