Line, tree, star or daisy-chain: EtherCAT supports almost all topologies. Pure bus or line topologies with many nodes are possible without limitations. When wiring the system, the combination of lines with branches or drop lines is particularly beneficial: the ports necessary to create branches are directly integrated in many I/O modules, so no additional switches or active infrastructure components are required. Naturally, the star topology, the Ethernet classic, can also be utilized.
Modular, complex machines switch network segments or individual nodes during operation (Hot Connect). EtherCAT slave controllers already include the basis for this feature. If a neighboring station is removed, the port is automatically closed so the rest of the network continues to operate without interference. Very short detection times < 15 μs guarantee a smooth changeover.
This incredible flexibility results from cable options: Inexpensive Industrial Ethernet cables can be used between two nodes up to 100 m apart in 100BASE-TX mode. Fiber optics (such as 100BASE-FX) can be used for distances greater than 100 m. The complete range of Ethernet wiring is also available for EtherCAT.
The ample bandwidth of EtherCAT makes it possible to embed conventional fieldbus networks as an underlying system via an EtherCAT gateway, which is particularly helpful when migrating from a conventional fieldbus to EtherCAT. The changeover to EtherCAT is gradual, making it possible to continue using automation components that do not yet support an EtherCAT interface.
EtherCAT supports up to 65,535 devices per segment, so network expansion is virtually unlimited. Because of the practically unlimited number of nodes, modular devices such as “sliced” I/O stations are designed in such a way that each module is an EtherCAT node of its own. Hence, the local extension bus is eliminated; the high performance of EtherCAT reaches each module directly and without any delays, since there is now no gateway in the bus coupler or head station.
