Siemens SIMATIC NET PROFIBUS - Manual (Page 230)

Active Components for Optical Networks
8-2
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
8.1 Optical Bus Terminal OBT
Figure 8-1 Optical Bus Terminal
Uses
The OBT (Optical Bus Terminal) is used to attach a single PROFIBUS node
without an integrated optical interface or a PROFIBUS RS-485 segment with up to
31 nodes to the optical PROFIBUS. The OBT therefore provides the advantages
of optical data transmission for existing DP devices.
A single PROFIBUS–DP node is attached using its RS–485 port via a connecting
cable terminated at both ends, for exampledrop cable 830–1T, to the RS-485 port
of the OBT. The OBT is included in the optical bus two FO interfaces.
The following optical transmission media can be connected to an OBT:
S Plastic fiber-optic cables can be used up to a distance of 50 m. These can be
assembled extremely simply with 2 x 2 simplex connectors on site.
S
PCF fiber-optic cables can be used for distances up to 300 m. These cables
must be ordered preassembled.
Design
The OBT has a compact, plastic casing. It is suitable both for mounting on a rail
and for wall mounting (two holes available for screws).
The OBT has the following connections:
S
9-pin sub-D female connector for connection of a PROFIBUS RS-485 segment
with nodes such as programming devices (PG), PCs, operator panels (OP) or
nodes without an integrated optical interface, for example an ET 200B or DP
components of other manufacturers
S
Two optical interfaces for attaching plastic and PCF fiber-optic cables with
simplex connectors (connection to CP 342-5 FO, IM 467 FO or ET 200 with an
integrated optical interface)
2
S
24 V DC power supply
2) For further information, refer to the catalog “PROFIBUS & AS-Interface”.