Siemens SIMATIC NET PROFIBUS manual Characteristics of the Optical Transmission Technique, Obt

PROFIBUS NETWORKS

Restrictions:

SFrame throughput times are increased compared with an electrical network

SThe assembly of glass fiber-optic cables with connectors requires specialist experience and tools

SThe absence of a power supply at the signal coupling points (node attachments, OLMs, OBTs) stops the signal flow

Characteristics of the Optical Transmission Technique

The optical transmission technique has the following characteristics:

Network topology:	Bus structure with integrated optical ports and OBT;
	bus, star or ring structure with OLMs
Medium:	Fiber-optic cables with glass, PCF or plastic fibers
Link lengths	With glass fibers up to 15,000 m dependent on the fiber and OLM
(point-to-point)	type
	with plastic fibers:
	OLM:	0 m to 80 m
	OBT:	1 m to 50 m
Transmission rate:	9.6 Kbps, 19.2 Kbps, 45.45 Kbps, 93.75 Kbps, 187.5 Kbps, 500
	Kbps, 1.5 Mbps, 3 Mbps*, 6 Mbps*, 12 Mbps
Number of nodes:	Maximum of 127 per network (126 with ring structure with OLMs)

* not with integrated optical ports and OBT

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.

PROFIBUS Networks SIMATIC NET	1-13
6GK1970-5CA20-0AA1 Release 2 05/2000