Fieldbus Communication • 71ETHERNETWAGO-I/O-SYSTEM 750ETHERNET TCP/IP4.1.2.1 Transmission MediaGeneral ETHERNET transmission standardsFor transmitting data the ETHERNET standard supports numeroustechnologies with various parameters (e.g., transmission speed, medium,segment length and type of transmission).1Base5 Uses a 24 AWG UTP (twisted pair cable) for a 1Mbps baseband signal fordistances up to 500 m (250 m per segment) in a physical star topology.10Base2 Uses a 5 mm 50 Ohm coaxial cable for a 10Mbps baseband signal for distancesof up to 185 m in a physical bus topology (often referred to as Thin ETHERNETor ThinNet).10Base5 Uses a 10 mm 50 Ohm coaxial cable for a 10Mbps baseband signal for distancesof up to 500 m in a physical bus topology (often referred to as ThickETHERNET).10Base-F Uses a fiber-optic cable for a 10Mbps baseband signal for distances of up to4 km in a physical star topology.(There are three sub-specifications: 10Base-FL for fiber-optic link, 10Base-FBfor fiber-optic backbone and 10Base-FP for fiber-optic passive).10Base-T Uses a 24 AWG UTP or STP/UTP (twisted pair cable) for a 10Mbps basebandsignal for distances up to 100 m in a physical star topology.10Broad36 Uses a 75 Ohm coaxial cable for a 10Mbps baseband signal for distances of upto 1800 m (or 3600 m with double cables) in a physical bus topology.100BaseTX Specifies a 100 Mbps transmission with a twisted pair cable of Category 5 andRJ45-connectors. A maximum segment of 100 meters may be used.Tab. 4-1: ETHERNET Transmission StandardsBeyond that there are still further transmission standards, for example:100Base-T4 (Fast ETHERNET over twisted conductors), 100Base-FX (FastETHERNET over fiber-optic cables) or P802.11 (Wireless LAN) for awireless transmission.The media types are shown with their IEEE shorthand identifiers. The IEEEidentifiers include three pieces of information.The first item, for example, “10”, stands for the media.The third part of the identifier provides a rough indication of segment type orlength. For thick coaxial cable, the “5” indicates a 500 meter maximum lengthallowed for individual thick coaxial segments. For thin coaxial cable, the “2”is rounded up from the 185 meter maximum length for individual thin coaxialsegments. The “T” and “F” stand for ‘twisted pair’ and ‘fiber optic’, andsimply indicate the cable type.
