Siemens SIMATIC NET Provozní pokyny stáhnout pdf (Strana 29)

Configuring Networks

3-3

SIMATIC NET Twisted-Pair and Fiber-Optic Networks

C79000-G8976-C125-02

Optical Budget in SIMATIC NET Industrial Ethernet (10BASE-FL)

The 10BASE-FL optical ports operate at a wavelength of 850 nm. In Industrial

Ethernet, the following optical budget is available:

S 50/125 µm fiber: 8 dBm

S 62.5/125 µm fiber: 11 dBm

This power budget can be “used up” as power loss through the fiber-optic

transmission path.

Optical Power Loss

The optical power loss is the cumulative value of all the losses occurring in the

fiber-optic transmission path. These losses can be attributed mainly to the

following causes:

S Power loss within the fiber itself at a wavelength of 850 nm (refer to the

technical specifications of the particular fiber)

S Power loss caused by splices (approximately 0.2 dB per splice)

S Power loss caused by connectors (approximately 0.4 dB per connector)

The values in brackets are approximate values that can be used as a guideline

when configuring a network. The actual link loss should always be checked after

the link has been installed using a power loss measuring device.

If the power loss is equal to or lower than the power budget, the planned fiber-optic

link can be implemented.

The optical power is generally specified in dBm. The dBm unit describes the

logarithmic power ratio to the reference power 1 mW.

Power losses of fibers and splices or connectors are specified in dB.

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Siemens SIMATIC NET Provozní pokyny Strana 29