Technical data

Active components
4.2 Active components for optical networks
PROFIBUS Network Manual
84 System Manual, Edition 04/2009, C79000-G8976-C124-03
4.2 Active components for optical networks
4.2.1 Optical bus terminal OBT
Figure 4-13 Optical bus terminal (OBT)
Area of application
The OBT (Optical Bus Terminal) is used to attach a single PROFIBUS node without an
integrated optical interface or a PROFIBUS RS485 segment with up to 31 nodes to the
optical PROFIBUS. The OBT therefore provides the advantages of optical data transmission
for existing DP devices.
The RS-485 interface of an individual PROFIBUS DP node is connected via a cable
terminated at both ends (for example connecting cable 830-1T) to the RS-485 interface of
the OBT. The OBT is integrated into the optical line using two optical interfaces.
The following optical transmission media can be connected to the OBT:
● Plastic fiber-optic cables can be used up to an individual segment length of 50 m. They
can be assembled easily on site by fitting 2 x 2 simplex connectors.
● PCF fiberoptic cables can be used for distances up to 300 m. These cables are
preassembled.
Design
The OBT has a compact plastic housing. It is suitable for mounting on a DIN rail or for wall
mounting using two holes drilled through it.
The OBT has the following connectors: