User Manual Controller Board for Siemens SIMATIC S5-95U_100U PLCs

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1.3.2 Remote Bus
The remote bus covers long distances within a system. The entire remote bus
may be up to 12.8 km long (from the controller board up to the last connected
remote bus device). This is achieved by dividing the entire INTERBUS system
into individual bus segments.
There are two types of bus segments:
- Remote bus segment
- Local bus segment (which also includes the INTERBUS ST compact station)
Each bus segment type is numbered consecutively, starting with 0 (viewed from
the controller board).
A remote bus segment consists of a BK module and the remote bus section
which lies between the BK module of the segment and the next BK module lead-
ing to the controller board.
The local bus segment consists of a BK module and the local bus (or an
INTERBUS ST compact station) which is connected to it.
A remote bus segment may bridge a distance of 400 m. In this way, the complete
remote bus can be divided into up to 256 remote bus segments
(see Figure 1-4, page 1-10).