Westermo U200 Operator manal - Manual (Page 6)

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3 Ethernet – Industrial Ethernet
3.1 History of Ethernet
In late 1972, Metcalfe and his Xerox PARC colleagues developed the first experimental
Ethernet system to interconnect the Xerox Alto, a personal workstation with a graphical user
interface. The experimental Ethernet network was used to link Altos to each other, and to
servers and laser printers.
The signal clock for the experimental Ethernet interface was derived from the Alto's system
clock, which resulted in a data transmission rate on the experimental Ethernet of 2.94 Mbps.
Robert Metcalfe's first experimental network was called the Alto Aloha Network.
In 1973, Robert Metcalfe changed the name to "Ethernet," to make it clear that the system
could support any type of computer; not just the Xerox Altos and to point out that his new
network mechanisms had evolved well beyond the Aloha system. He chose to base the name
on the word "ether" as a way of describing an essential feature of the system: the physical
medium (i.e., a cable) carries bits to all stations, much the same way that the old "luminiferous
ether" was once thought to propagate electromagnetic waves through space. Thus, Ethernet
was born.”
``The diagram ... was drawn by Dr. Robert M. Metcalfe in 1976 to present Ethernet ... to the
National Computer Conference in June of that year. On the drawing are the original terms for
describing Ethernet. Since then other terms have come into usage among Ethernet
enthusiasts.''
Figure 1
3.2 Industrial Ethernet – What Are The Differences?
Ethernet is moving into the Automation Industry. Manufacturers are exporting their legacy
protocols onto Ethernet, designing new IP based communication protocols and providing
embedded Web-Pages within PLCs to provide real-time information using simple tools like
Internet Explorer and Netscape.