Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide User Manual
Page 80
80
Rockwell Automation Publication CNET-IN001C-EN-P - October 2011
Glossary
local area network
Family of computer networks, industrial control networks, and office networks
used in short-distance, multi-user environments.
loss
see
multi-mode
Class of fibers where the light travels in multiple paths down the fiber core.
numerical aperture (NA)
In a lens or fiber, the sine of half the maximum angle of acceptance
α
. NA = sin
α
= √
(n1
2
- n2
2
) where n1= core refractive index and n2=cladding refractive index.
network update time (NUT)
Time necessary to complete the scheduled bandwidth, unscheduled bandwidth,
and network maintenance in the network interval.
OTDR (optical time
domain reflectometer)
Tool for characterizing fiber attenuation, uniformity, splice loss, breaks, or length.
photo diode
see
pin diode
Used as a receiving device in fiber optic systems to detect the presence of light and
convert that light energy into electrical energy.
plastic clad silica fiber
Step-index fiber made from silica core and a plastic cladding.
plastic fiber
fiber consisting only of plastic with usually higher attenuation than glass.
receiver
Produces logic levels in a fiber optic system by using photo diodes, resistors,
amplifiers, and level shift circuits.
refractive index
Ratio of the speed of light in a vacuum to the speed of light in the material.
responsivity
Ratio of output current/voltage to the optical input power.
return loss
Logarithmic ratio of power into a device to the power reflected back due to
mismatches in a system. Return Loss = 10 × log (P
in
/P
back
).
scheduled maximum node address
(SMAX)
Highest scheduled node address on the ControlNet network.
sensitivity
Minimum optical power amplitude at the input of a receiver in order to achieve a
predefined BER.
single-mode
Class of fibers in which light travels in a single path down the fiber core.
speed of light
Phase velocity of an optical wave in a vacuum.