Siemens SIMATIC NET PROFIBUS manual Optical Bus Terminal OBT

Active Components for Optical Networks

8.1Optical 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:

SPlastic 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.

SPCF 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:

S9-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

STwo 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

S24 V DC power supply

2)For further information, refer to the catalog “PROFIBUS & AS-Interface”.

8-2	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000