Technical information
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Presentation
Technical information
Ethernet network
Infrastructure
Presentation
The ConneXium Industrial Ethernet offer comprises a complete family of products
and tools (including the ConneXium Network Manager (CNM) software tool) required
to build the infrastructure of an Industrial Ethernet network. The following pages
provide information on network design and component selection.
Ofce Ethernet versus Industrial Ethernet
There are three main areas of differentiation between Ethernet applications in an
ofce environment and those in an industrial environment:
b Environment
b Layout (not physical layer specication)
b Performance
Contrary to the ofce environment and even though ISO/IEC is working on it, as yet
there are no clearly dened specications for Ethernet devices intended for
industrial applications. The specications of what it is called Industrial Ethernet are
dened by different agencies or entities based upon its nature and what the
automation market has traditionally used.
The environmental specications of Industrial Ethernet devices are dened by the
traditional agencies that dene the environmental specications for standard
industrial devices (UL, CSA, e, etc.).
IEEE 802.3 denes the physical layer specications of the Ethernet network (types
of connector, distance between devices, number of devices, etc.) while standard
11801 (similar to TIAEIA 568B and CENELEC EN 50173) provides layout guidelines
for installers.
The performance specications are currently being drawn up by ISO/IEC.
Ethernet 802.3 principles
The Ethernet 802.3 Link Layer is based on a collision detection mechanism
(CSMA CD) whereby every node whose information has collided on the network
detects the collision and re-sends the information.
The process of re-sending information causes delays in its propagation and could
affect the application.
A collision domain is a group of Ethernet end devices interconnected by hubs or
repeaters (devices that receive information and send it out to all their other ports, no
matter where the destination device is connected). This means that all devices will
be affected by collisions.
With full duplex switches (devices that receive information and only send it out through
the port to which the destination device is connected), there are no collision domains.
Therefore, for industrial automation applications it is highly advisable to use full
duplex switches to interconnect devices. This will help eliminate collision domains.
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