Siemens S7-300 - Permitted Cable Lengths in a PROFIBUS Subnet Segment

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
A5E00203919-01
5-43
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The cable length in a segment of a PROFIBUS subnet depends on the
transmission rate.
Table 5-24 Permitted cable lengths in a PROFIBUS subnet segment
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9.6 Kbps to 187.5 Kbps 1,000 m
500 Kbps M 400
1.5 Mbps M 200
3 Mbps to 12 Mbps M 100
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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 Stub cable lengths per segment
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9.6 Kbps to 93.75
Kbps
M 96 32 32
187.5 Kbps M 75 32 25
500 Kbps M 30 20 10
1.5 Mbps M 10 6 3
3 Mbps to 12 Mbps
1) 1) 1)
1)
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.