Technical data

Network configuration
3.2 Configuring optical networks
PROFIBUS Network Manual
54 System Manual, Edition 04/2009, C79000-G8976-C124-03
3.2.5 Calculating the signal loss on glass fiber-optic links with OLMs
Calculation examples
The following work sheets show typical calculations of the power budget for SIMATIC NET
PROFIBUS glass optical fibers, one with OLM/G11, OLM/G12 at a wavelength of 860 nm
and one with OLM/G111300 and OLM/G121300 at a wavelength of 1300 nm.
Note
Please note that the information on fiber attenuation in the data sheets and type
specifications of fiberoptic cables is based on measurements with narrowband laser light
sources precisely adapted to the wavelengths.
The LED transmission elements used in practice produce a wider band spectrum whose mid
frequency deviates slightly from the measured wavelength.
You should therefore use the following attenuation values on all connections with SIMATIC
NET multimode glass fiberoptic cable between SIMATIC NET PROFIBUS components:
3.5 dB/km at 860 nm
1.0 dB/km at 1310 nm
Note
The following distances between 2 OLMs must not be exceeded regardless of the optical
power budget:
OLM/P11, OLM/P12 400 m
OLM/G11, OLM/G12, OLM/G12-EEC 3 km
OLM/G11-1300, OLM/G12-1300 15 km