Siemens Advance Network Gateway User Manual page 70

Definitions
Overview
Advance Network
Gateway Ethernet
Ethernet
Collisions
CRC - Cyclic
Redundancy Check
DataNET
Data Hiway
2000590-001
Glossary
This section defines important Terms.
The Advance Network Gateway Ethernet (ANG_EN) is a wall- (or rack-)
mounted unit that is self-contained with power supply and all electronics.
It provides internal field termination points to connect standard Advance
Data Hiway cable "on one side" and Ethernet 10BaseT cabling (Un-
shielded Twisted Pair) "on the other side". The Gateway unit requires
120 VAC power wired directly to it.
A data link level protocol comprising the OSI model's bottom two layers.
Ethernet is a broadcast networking technology that uses several different
physical media, including twisted-pair cable and coaxial cable. Ethernet
usually used CSMA/CD. TCP/IP is commonly used with Ethernet net-
works.
The result of two or more LAN stations attempting to use the same
transmission medium at the same time. Collisions are a normal occur-
rence on Ethernet. A properly functioning Ethernet will experience a rela-
tive small percentage of collisions. Typically the collision rate should be
less than 5% of the available bandwidth. Most collisions occur during the
preamble portion of the frame. Most Ethernet controllers automatically
retry, up to 15 times, any packet that has a collision during transmission.
(Except for Late Collisions)
CRC is a method to detect errors. A number is derived from the data that
will be transmitted. By recalculating the CRC at the remote end and
comparing it to the value originally transmitted, the receiving node can
detect errors.
The name "DataNET" is used by Siemens Applied Automation to mean
the high-speed communication system inclusive of our application soft-
ware.
The term "Data Hiway" refers to the Advance Optichrom Network. The
Advance Network Gateway and DataNET Gateway are used to bridge
the Advance Optichrom network and the Advance DataNET network.
Glossary 63