Siemens SIMATIC S7-400 Hardware And Installation Manual page 126

Networking
Lengths of Spur Lines
If you do not fit the bus cable directly at the bus connector (for example, when
using a PROFIBUS-DP bus terminal), you must take into account the maximum
possible spur line length.
The following table gives the maximum lengths of spur lines allowed per bus
segment:
Upward of 3 Mbps use PG connecting cable, order no. 6ES7 901-4BD00-0XA0, to
connect the programming device or PC. You can use two or more PG connecting
cables with this order number in one bus configuration. Different spur lines are not
allowed.
Table 5-3 Lengths of Spur Lines per Segment
Transmission Rate
9.6 to 93.75 Kbps
187.5 Kbps
500 Kbps
1.5 Mbps
3 to 12 Mbps
5-16
www.gkbpx.com
Max. Lengths of Spur No. of Nodes per Spur Line Length
Lines per Segment
96 m
75 m
30 m
10 m
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S7-400 and M7-400 Programmable Controllers, Installation Manual
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1.5 m or 1.6 m 3 m
32 32
32 25
20 10
6 3
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C79000-G7076-C424-01