Functional Principle
Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs) frame. Using one frame per node per cycle leads to low bandwidthIn computer networking, bandwidth often refers to a data rate measured in bits/s, for example, network throughput. The reason for the connection of data rate with the term bandwidth is that the limit to the data rate of a physical communication link is related to its bandwidth in hertz utilization and thus to poor overall network performance. EtherCATEtherCAT is an open, high-performance Ethernet-based fieldbus system. The development goal of EtherCAT was to apply Ethernet to automation applications which require short data update times (also called cycle times) with low communication jitter (for synchronization purposes) and low hardware costs therefore takes a different approach, called "processing on the fly" (for more details, refer to EtherCAT Implementation).
With EtherCAT, the Ethernet packet or frame is no longer received, and then interpreted and copied as process data at every node. Instead, the EtherCAT slave devices read the data addressed to them while the telegram passes through the device. Similarly, input data is inserted while the telegram passes through. The frames are only delayed by a fraction of a microsecond in each node, and many nodes - typically the entire network - can be addressed with just one frame.
