Siemens SIMATIC NET PROFIBUS User Manual

3-17

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

The length of the transmission path on fiber-optic cables is not dependent on the
transmission rate.

Each node on the optical PROFIBUS network has repeater functionality so that the
following distance information relates to the distance between two adjacent,
interconnected PROFIBUS nodes.

The maximum cable length between two PROFIBUS nodes depends on the type
of fiber-optic cable used and the optical network components.

Table 3-7

Permitted Cable Lengths with Integrated Optical Interfaces or OBT

Plastic fiber-optic,
duplex cord

50

1550

Plastic fiber-optic,
standard cable

50

1550

PCF fiber-optic,
standard cable

300

9300

Table 3-8

Permitted Cable Lengths in an OLM Network

Plastic fiber-optic,
duplex cord

50

1550

Plastic fiber-optic,
standard cable

80

2480

PCF fiber-optic,
standard cable

400

12400

S

Optical buses can contain max. 32 integrated optical interfaces in series.

S

Several buses of up to 32 integrated optical interfaces can only be linked
via OBTs (optical repeaters).

S

In optical networks (bus, star, ring) containing only OLMs, the number of
OLMs is limited to 122.

S

The number of all optical components (integrated interfaces, OBTs,
OLMs) in the optical PROFIBUS network must be specified in the
configuration tool as the “Number of OLM, OBT” parameter (see Section
3.3). This number must not exceed 122.