
Industrial Ethernet Networks
2-6
SIMATIC NET Twisted-Pair and Fiber-Optic Networks
C79000-G8976-C125-02
2.3 Fast Ethernet
Fast Ethernet /5/ has the essential features of the classic Ethernet standard with a
data rate increased by a factor of 10 to 100 Mbps. The data format, the CSMA/CD
protocol and the glass fiber-optic cables and category 5 twisted-pair cables are
identical in both systems.
SIMATIC NET products support the following Fast Ethernet specifications:
– 100BASE-TX over category 5 twisted-pair cable (two pairs)
– 100BASE-FX over fiber-optic cable (2 fibers)
Table 2-1 Ethernet/Fast Ethernet Compared
Ethernet Fast Ethernet
IEEE standard 802.3 802.3u
Data rate 10 Mbps 100 Mbps
Duration of a bit 100 ns 10 ns
Access technique CSMA/CD
Longest packet 1518 bytes
Shortest packet 64 bytes
Address field length 48 bits
Topology star, tree, bus
Table 2-1 Ethernet/ Fast Ethernet in SIMATIC NET
Ethernet Fast Ethernet
Supported media Coax: 10BASE5
Twisted pair: 10BASE-T
FO: 10BASE-FL
Twisted pair: 100BASE-TX
FO: 100BASE-FL
Network components Transceivers
OLM
ELM
ASGE
Mini UYDE
Mini OTDE
OSM
ESM
Max. length of a TP trunk
segment
100 m 100 m
Max. length of an FO trunk
segment
Multimode: 3000 m Multimode: 3000 m
Single mode: 26 km
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