Technical information

8/2
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.
Ofce Ethernet versus Industrial Ethernet
There are three main areas of differentiation between Ethernet applications in an
ofce environment and those in an industrial environment:
b Environment
b Layout (not physical layer specication)
b Performance
Contrary to the ofce environment and even though ISO/IEC is working on it, as yet
there are no clearly dened specications for Ethernet devices intended for
industrial applications. The specications of what it is called Industrial Ethernet are
dened by different agencies or entities based upon its nature and what the
automation market has traditionally used.
The environmental specications of Industrial Ethernet devices are dened by the
traditional agencies that dene the environmental specications for standard
industrial devices (UL, CSA, e, etc.).
IEEE 802.3 denes the physical layer specications 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 specications 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.
2
1
3
4
5
6
7
8
9
10
2
1
3
4
5
6
7
8
9
10