Siemens SIMATIC NET PROFIBUS - Manual (Page 31)

Topologies of SIMATIC NET PROFIBUS Networks
2-5
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Table 2-1 Bus Attachment Components for Transmission Rates up to 12 Mbps, continued
Optical Bus Terminal OBT 6GK1 500-3AA0
PROFIBUS Terminator 6ES7 972-0DA00-0AA0
2.2 Topologies of Optical Networks
Interfacing Electrical and Optical Networks/Components
If you want to cover larger distances with the fieldbus regardless of the
transmission rate or if the data traffic on the bus is threatened by extreme levels of
external noise, you should use fiber-optic cables instead of copper cable.
To interface electrical cables with fiber-optic cables, you have the following
possibilities:
S
The PROFIBUS nodes with a PROFIBUS DP interface (RS-485) are attached
to the optical network using an optical bus terminal (OBT) or using an optical
link module (OLM).
S
PROFIBUS nodes with an integrated FO port (for example ET 200M (IM 153-2
FO), S7-400 (IM 467 FO)) can be connected directly to an optical network with
a bus topology.
S
Optical networks with a larger network span or structured as redundant rings
should be implemented using OLMs.
The structure of optical networks using optical link modules (OLMs) is described in
detail in later chapters in this manual.
For information about the structure of an optical PROFIBUS network with
PROFIBUS nodes having an integrated FO interface, refer also to the ET200
system manual.