Permitted Cable Lengths In A Profibus Subnet Segment - Siemens S7-300 Installation Manual

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The cable length in a segment of a PROFIBUS subnet depends on the
transmission rate.
Table 5-24
9.6 Kbps to 187.5 Kbps
500 Kbps
1.5 Mbps
3 Mbps to 12 Mbps
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If you want to implement cable lengths above those permitted in a segment, you
must use RS485 repeaters. Information on this topic can be found in the RS485
repeater product information.
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If bus nodes are connected to a bus segment via stub cables (e.g. PG via a normal
PG cable), then you must consider the maximum possible length of the stub cable.
The following table lists the maximum permitted lengths of stub cables per
segment:
Table 5-25
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9.6 Kbps to 93.75
Kbps
187.5 Kbps
500 Kbps
1.5 Mbps
3 Mbps to 12 Mbps
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At 3 Mbps and higher, use the PG patch cord (Order No. 6ES7 901-4BD00-0XA0) to
connect the PG or PC. You can use multiple PG patch cords of this number in an
installation. Do not use any other type of stub cable.
S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
A5E00203919-01

Permitted cable lengths in a PROFIBUS subnet segment

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Stub cable lengths per segment
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M 96
M 75
M 30
M 10
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1,000 m
M 400
M 200
M 100
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32 32
32 25
20 10
6 3
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5-43