Instructions

Tips & Tricks
78 © KUNBUS
10 Tips & Tricks
10.1 Cable Lengths in PROFIBUS segments
The maximum cable lengths of PROFIBUS segments are
specified in the standard EN 50170, part 2, in dependency from
the transmission rate used. Here, the indicated value applies
only for segments with copper cables type A, without using
repeaters.
The following table shows the maximum segment lengths,
depending on the baud rate:
Transmission rate Max. segment length
9.6 Kbit/s 1200 m
19.2 Kbit/s 1200 m
45.45 Kbit/s 1200 m
93.75 Kbit/s 1200 m
187.5 Kbit/s 1000 m
500.0 Kbit/s 400 m
1.5 Mbit/s 200 m
3.0 Mbit/s 100 m
6.0 Mbit/s 100 m
12.0 Mbit/s 100 m
Table 1 Segment length specification
10.2 Segment Cascading
According to the standards it is permissive to make a cascade
connection with 4 cable segments, separated by repeaters. For
individual applications this guideline can be deviated from.
However, if there should be sporadic errors in the bus segment,
we recommend a timing check with a bus monitor, and
possibly a reduction to the specified 4 segments.