198 ï Fieldbus CommunicationETHERNETWAGO-I/O-SYSTEM 750Linux Fieldbus Coupler10.1.2.3 Coupler ModulesThere are a number of hardware modules that allow for flexible arrangementfor setting up an ETHERNET network. They also offer important functions,some of which are very similar.The following table defines and compares these modules and is intended tosimplify the correct selection and appropriate application of them.Module Characteristics/application ISO/OSIlayerRepeater Amplifier for signal regeneration, connection on a physical level. 1Bridge Segmentation of networks to increase the length. 2Switch Multiport bridge, meaning each port has a separate bridgefunction.Logically separates network segments, thereby reducing networktraffic.Consistent use makes ETHERNET collision-free.2 (3)Hub Used to create star topologies, supports various transmissionmedia, does not prevent any network collisions.2Router Links two or more data networks.Matches topology changes and incompatible packet sizes (e.g.used in industrial and office areas).3Gateway Links two manufacturer-specific networks which use differentsoftware and hardware (i.e., ETHERNET and Interbus-Loop).4-7Tab. 10-2: Comparison of Coupler Modules for Networks10.1.2.4 Transmission ModeSome ETHERNET based WAGO couplers/controllers support both 10Mbit/sand 100Mbit/s for either full or half duplex operation. To guarantee a safe andfast transmission, both these couplers/controllers and their link partners mustbe configured for the same transmission mode.NoteA faulty configuration of the transmission mode may result in a link losscondition, a poor network performance or a faulty behavior of thecoupler/controller.The IEEE 802.3u ETHERNET standard defines two possibilities forconfiguring the transmission modes:• Static configuration• Dynamic configuration
