Installation guide

Network Infrastructure for EtherNet/IP™
Planning the Infrastructure
3-20
communications is used. Cable lengths of 2000 meters (6562 ft) are possible using multimode fiber in
full-duplex, 100-Mbps applications. The use of pre-terminated glass fiber-optic cables is recommended.
Fiber-optic cables are terminated using SC, ST, or MTRJ connectors. Like twisted-pair wiring, the use of
half-duplex communications has additional restrictions as to how many hubs can be used between the
sending and receiving devices. These issues are covered in more depth in 4 Designing the Infrastructure.
3.3.4.2 Plastic Fiber Cable
For cabling within cabinets or over short distances in conjunction with media converters, plastic fiber
optics provide noise immunity and easier connection capability, especially if custom cables need to be
used. Polymer (980/1000 um) fiber cables can be used for lengths up to 50 meters (164 ft), while HCS
(200/230 um) fiber cables can be used for up to 100 meters (328 ft).
3.3.4.3 More Cabling Resources
An overview of characteristics to consider when selecting connectors and cables suitable for industrial
applications can be found in 7 Selecting Components. For complete connector, cabling, and layout
information, refer to the EtherNet/IP™ Media Planning and Installation Guide available from ODVA.
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3.3.5 Wireless Ethernet
Wireless Ethernet network systems use radio frequency (RF) transmitters and receivers to send and
receive data. Like any system based on radio, performance and interference issues need to be addressed
for use on the plant floor. Wireless systems are based on the IEEE Std 802.11b and other standards;
however, this remains an emerging area for industrial Ethernet applications and is not covered here.
3.4 Ethernet Data Connections
Ethernet data packets are sent in the format shown in Figure 3-2.
Figure 3-2 Typical Layout of an Ethernet Data Packet.
This data format is used to implement the Media Access Control (MAC) protocol that allows a device to
“talk” on the Ethernet network. Each MAC device has a unique
Source Address (SA) comprised of a 6-
byte number (48 bits or 12 hexadecimal digits) that was assigned to it at the time of manufacture. The
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ODVA, Inc., EtherNet/IP™ Media Planning and Installation Guide, Ann Arbor: 2006. www.odva.org