industrial//industrial communication//industrial Ethernet//EtherCAT

EtherCAT is an industrial Ethernet protocol, developed by Beckhoff, in which a single frame sweeps through every device of a chain and each one reads and writes its own bytes as the frame passes, and it is the network behind servos, coordinated axes and fast machine I/O.

EtherCAT is an industrial Ethernet protocol, developed by Beckhoff, in which a single frame sweeps through every device of a chain and each one reads and writes its own bytes as the frame passes, and it is the network behind servos, coordinated axes and fast machine I/O.

Its defining trick: a single frame travels through every node in a chain (master, then servo, then servo, then servo) and each device reads and writes its bytes on the fly while the frame passes, instead of receiving, processing and answering it. The chain becomes one long shift register that a single frame sweeps through, where PROFINET keeps each device a normal Ethernet node and schedules around it: EtherCAT is faster and tighter, PROFINET fits better into an ordinary switched plant. Latency is measured in microseconds.

The numbers explain where it lives. At 100 Mbit/s, with up to 100 m of cable between neighbours, a whole machine is refreshed in cycles of 100 µs to 1 ms, and the nodes share distributed clocks synchronized below a microsecond, so dozens of axes sample their positions and apply their currents at the same instant. That shared instant matters as much as the speed: a multi-axis path is only as good as the agreement of its axes on when now is (time synchronization).

That is what hyper-deterministic means in practice, and why it is the network behind coordinated axes and CNC-grade motion (motion control). Against CAN, which shares a slower bus by priority and suits many small controllers exchanging short messages, EtherCAT gives one master a fixed, fast view of every device; the bus budget of a serial bus becomes a cycle budget fixed at design time (determinism).

Comparisons such as a hundred times faster than CAN are rules of thumb, never a law: the ratio depends on bit rate, frame size, the number of nodes and how the cycle is configured. What holds is the shape: CAN moves short prioritized messages on a shared bus, EtherCAT refreshes a fixed process image on a schedule.

The price is a dedicated segment and a master that owns it. EtherCAT reuses Ethernet frames and discards the TCP/IP path (no addressing per packet, no retransmission, no waiting) to buy a bound on timing, so its frames are not routed like normal IP traffic and the motion network is a separate world from the plant network that carries SCADA, OPC UA and MQTT (protocol stack).