Siemens SIMATIC NET PROFIBUS Instrukcje Operacyjne Pobierz pdf (Strona 38)

Installation and Maintenance

5.1 Installation

SIMATIC NET PROFIBUS Optical Link Module OLM V4.0

32 Operating Instructions, 01/2013, C79000-G8976-C270-03

Example:

OLM / G12, wavelength 860 nm, fiber 62.5/200 µm

send

= 13 dBm

receiver

= 28 dBm

optical link margin = 28 dBm -13 dBm= 15 dBm

max. line length = 3 km

attenuation = 3.5 dB/km @ 860 nm

max. line attenuation = 3.5 dB/km * 3 km = 10.5 dB

optical power margin = optical link power budget – max. line attenuation

= 15 dBm – 10.5 dBm = 4.5 dBm

This link power margin may not be infringed on by the user, because it may lead to errors at

the optical interface!

You should also remember that the maximum line lengths are only valid for unspliced cables.

If splices are used in the configured plant, their loss must be added to the cable loss.

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Siemens SIMATIC NET PROFIBUS Instrukcje Operacyjne Strona 38