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What is Ethernet?
Ethernet is a well known and widely used communication protocol that has been in existence since the 1970's when it was developed by Xerox. Since that time it has expanded rapidly and today it is the most commonly used LAN in existence. We know Ethernet best for its everyday uses such as email, Internet and Intranet.
Availability of Ethernet
Ethernet is an open platform serial communication which is vendor neutral. It is governed by the IEEE 802.3 standard adopted in 1985. Due to the large market and availability, Ethernet component choices are numerous and inexpensive. Since Ethernet is a standard, connectivity between a wide range of Ethernet capable products is fast and easy.
The medium over which Ethernet communication is transmit-ted is varied. The most common medium to date is 10Base-T. 10Base-T means a 10-Mbps (10 million bits per second) baseband signal carried over twisted pair cable. Most facilities using Ethernet are using 10Base-T as their medium. Other mediums used are 10Base5 and 10Base2, thick coaxial and thin coaxial cable respectively. 10Base-F is a fiber optic medium. The next step in Ethernet technology is the 100-Mbps Fast Ethernet. This will most likely become a standard over the next few years.
Ethernet is a form of serial communication so it must have a protocol associated with it to ensure that data is sent and received reliably. Ethernet uses the CSMA/CD (Carrier Sense Multiple Access with Collision Detection). The CSMA/CD protocol means that an Ethernet station must first check to make sure the channel is not carrying a signal (Carrier Sense). Every station has equal access to the channel and no single station can lock out another station (Multiple Access). When more than one station detects that the channel is free and starts transmitting, a collision occurs. Each station is notified of the collision and re-transmissions are scheduled at a random time interval on each station (Collision Detection). Most collisions are handled within microseconds of detection.
Ethernet is a standard of communication between hardware devices. TCP/IP (Transfer Control Protocol/Internet Protocol) is a standard used by many applications to communicate between software, hardware and between networks. TCP/IP is also an open standard protocol making it very accessible. TCP/IP is what provides a common interface between devices.
The availability of the Ethernet and TCP/IP standard, a wide range of Ethernet products, extremely fast communications and a proven communication protocol make Ethernet a perfect choice for networking and communication between industrial devices.
Parker Hannifin Corporation, Compumotor Division,
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