Siemens SIMATIC NET PROFIBUS manual Combination of Integrated Optical Interfaces and OLMs

Topologies of SIMATIC NET PROFIBUS Networks

2.2.3Combination of Integrated Optical Interfaces and OLMs

Note

The optical ports of the OLMs are optimized for greater distances. The direct coupling of the optical ports of an OLM with an OBT or integrated optical ports is not possible due to differences in the technical specifications.

Attaching Glass FO Cables to Buses Made up of Integrated Optical Interfaces

The operating wavelength of the integrated optical interfaces and the OBT is optimized for the use of plastic or PCF fibers. The direct attachment of glass FO cables is not possible.

If a link with glass FO cable is required, for example to span distances of more than 300 m, this link must be implemented with OLMs. The attachment of glass links to the optical bus made up of integrated optical interfaces is via the RS-485 interface of an OBT. The following schematic shows an example of an application:

PG

À

ET 200M with

IM 153-2 FO Field device without FO interface

OBT 4

À

1

OBT

1

À

3

À

OBT

À

1

3

À

OBT

1

À

À

2

Further nodes

1 up to 15 km

ÀTerminating resistor activated

1	FO cable	3	PROFIBUS 830-1T connecting cable
2	LAN cable for PROFIBUS	4	PROFIBUS 830-2 connecting cable

Figure 2-7 Attachment of an Optical Glass Link to an Optical Bus Made up of Integrated Optical Interfaces

PROFIBUS Networks SIMATIC NET	2-13
6GK1970-5CA20-0AA1 Release 2 05/2000