What is the fundamental principle behind EtherCAT?
The fundamental principle of EtherCAT is pass-through reading.
Pass through reading means that messages are not destined for a single node and consumed by that node. Instead, messages are transmitted to the following node in a string as they are processed.
A single message is issued by the EtherCAT Master with data for all nodes. As the message is transmitted around the ring and back toward the Master, each node reads its inputs and adds its outputs to the message. Without the deficiency of small payloads or messages targeted to specific nodes, an EtherCAT network can achieve maximum bandwidth utilization.