Chapter 3: Installation
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Page 22
3.3.5
Power Budget Calculations for LBH18x Fiber Media
Receiver Sensitivity and Transmitter Power are the parameters necessary to
compute the power budget. To calculate the power budget of different fiber media
installations using Black Box products, the following equations should be used:
OPB (Optical Power Budget) = P
T
(min) - P
R
(min)
where P
T
= Transmitter Output Power, and P
R
= Receiver Sensitivity
Worst case OPB = OPB - 1dB(for LED aging) - 1dB(for insertion loss)
Worst case distance = {Worst case OPB, in dB} / [Cable Loss, in dB/Km]
where the “Cable Loss” for 62.5/125 and 50/125
μ
m
(m.m.) is 2.8 dB/km,
and the “Cable Loss” for 100/140 (Multi-mode) is 3.3 dB/km,
and the “Cable Loss” for 9/125 (Single-mode) is 0.5 dB/km
* Note: The use of either multi-mode or single-mode fiber to operate at 100Mbps
speed over long distances (i.e., over approx. 400 meters) can be achieved
only
if the following factors are both applied:
•
The 100Mbps fiber segment must operate in full-duplex (FDX) mode, and
•
The worst-case OPB of the fiber link must be greater than the fiber cable’s
passive Attenuation.
(Attenuation = Cable loss + LED aging loss + Insertion loss + safety factor
3.3.6
Connections to NICs which support Auto-Negotiation
The copper ports of LBH08x/LBH18x Industrial Switches will function
properly with NICs (Network Interface Cards) which support Auto-Negotiation, and
the Fast Link Pulse (FLP) coding for the 100BASE-TX signaling system. When
connecting a NIC to the LBH08x/LBH18x, it may be necessary to reload the NIC
drivers on the user device if the NIC has been communicating with a protocol other
than 100BASE-TX (such as 10BASE-T). When 100Mbps operation is agreed and in
use, the SPEED LED is illuminated steady ON. It is OFF if there is no traffic or if 10
Mbps traffic.
3.4 Powering
the
LBH08x/LBH18x
The DC internal power supply supports installation environments where the
DC voltage is from 9 to 60 volts depending on the model selected. When connecting
the Ethernet cabling, there is no need to power down the unit. Individual cable
segments can be connected or disconnected without concern for power-related
problems or damage to the unit.
Power input options are available to suit the LBH08x/LBH18x Switches to
special high-availability communications and/or heavy industrial-grade applications,
including:
* 12VDC, -48VDC and 24VDC with single DC input
