Fieldbus
Communication
•
115
ETHERNET
WAGO-I/O-SYSTEM 750
PROFINET IO
4.1.2.3 Coupler
Modules
There are a number of hardware modules that allow for flexible arrangement
for 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 to
simplify the correct selection and appropriate application of them.
Module
Characteristics/application
ISO/OSI
layer
Repeater
Amplifier for signal regeneration, connection on a physical level. 1
Bridge
Segmentation of networks to increase the length.
2
Switch
Multiport bridge, meaning each port has a separate bridge
function.
Logically separates network segments, thereby reducing network
traffic.
Consistent use makes ETHERNET collision-free.
2 (3)
Hub
Used to create star topologies, supports various transmission
media, does not prevent any network collisions.
2
Router
Links two or more data networks.
Matches topology changes and incompatible packet sizes (e.g.
used in industrial and office areas).
3
Gateway
Links two manufacturer-specific networks which use different
software and hardware (i.e., ETHERNET and Interbus-Loop).
4-7
Tab. 4-2: Comparison of Coupler Modules for Networks
