Industrial ETHERNET

Industrial ETHERNET Lexicon
SCADA
SDH
Supervisory Control and Data Acquisition
Term for systems for control and
visualization of processes. SCADA
systems are based on Windows
operating systems as a rule.
Synchronous Digital Hierarchy
A European standard that defines
several standards of transmission
rates and transmission forms for
optical fibers (fiber optic cable).
SLA
Lmax = (29 dB-3 dB) /0.3 dB/km
Lmax = 86.6 km
In this example, the maximum distance
to be covered is 86.6 km.
Signal bandwidths:
ETHERNET = 10 MHz, Fast ETHERNET
= 125 MHz and Gigabit ETHERNET
= 1.25 GHz
Service Level Agreement.
SFD
SFP
Start of Frame Delimiter
Part of an ETHERNET telegram.
Small form-factor pluggable.
A transceiver for 1 Gbps networks that
converts serial electric signals to serial
optical signals and vice versa. see also
GBIC.
SLIP
Serial Line Internet Protocol
A protocol for serial data transfer over
dialup connections such as the telephone.
It is used for connecting computers
that are not networked permanently over
LANs to the Internet. In comparison
to the more recent PPP, SLIP has the
disadvantage that erroneous data is not
recognized.
SHA-1 Secure Hash Algorithm 1
See also Hash.
SMON
Switch Monitoring.
Shared
Network
Term for an ETHERNET network in
which participants share the available
bandwidth. In these networks, the
CSMA/CD process controls the access
of the participants to the transmission
medium.
SMTP
SNAP
Simple Mail Transfer Protocol
Term for a protocol for sending e-mail
messages.
Subnetwork Access Protocol.
Single-mode
Fiber
278
A single-mode fiber is a fiber optic cable
that is characterized by its extremely
small core diameter (max. 10 µm). As a
result, in this fiber, the light after the
cutoff waveline can only get extended
along one path – one mode.
The distance that is to be covered by
a single-mode fiber depends on several
factors: the characteristic data of the
fiber, the link budget as well as the
attenuation to plug connectors, splices
and other components.
Example:
A 9/125 µm fiber with an attenuation (A)
of 0.3 dB/km should transmit a wavelength
of 1550 nm of Fast ETHERNET
data packets. The link budget is 29 dB.
A reserve of 3 dB is taken into account.
The attenuation of the plug connector
is to be ignored.
Attenuation:
Lmax = (Link Budget-Reserve)/
Fiber attenuation
SNMP
Simple Network Management Protocol
A protocol for network management.
SNMP defines commands for the
reading and writing of information,
status and error messages as well as
providing a structured model. This
model consists of agents with their
respective Management Information
Base (MIB) and a Manager. The Manager
is a program that runs on a network
management station. Agents are mostly
located within devices
such as switches, routers and terminal
devices that support the SNMP. The
task of the agents consists in collecting
and preparing data in the MIB. These
data is requested at regular intervals
by the Manager and displayed on the
network management station. The
devices are configured, for example,
with the data that the Manager writes to
the MIBs in question. In urgent cases,
the agent can also send messages
(traps) directly to the Manager.