EtherCAT

EtherCAT is an Ethernet-based family of computer network protocols that is essential for real-time control. Its goal is to use the Ethernet (Local Area Network connections) for automated applications that need cycle times, with low hardware costs, low fieldbus costs, and low communication jitters. It has a functional safety system and complies with international standards (ISO, SEMI and IEC).

An Overview

Most LAN automated networks work with short data per node (less than minimum payload of Ethernet frame). A frame for a node for one cycle means poor bandwidth utilization and, therefore, the network performs poorly. With EtherCAT, the frame for every node is not received, interpreted, and copied at every node. It simultaneously reads the data addressed to it, enters the device and inputs information. The frames work faster now because they are delayed by only less than a microsecond for each node. This means the entire network can use only one frame.

Where EtherCAT is Useful

EtherCAT is highly useful in technological processes that use heavy machinery. Quicker and better control of these machines is afforded through EtherCAT. Examples are metal forming, molding, printing machines, robotics, assembly systems, etc.

How the EtherCAT Works

The EtherCAT instruction/protocol is first transported within the standard IEEE 802.3 frame, using type 0x88a4. It may be composed of a couple of sub-datagrams, each of which serves a defined memory area of the logical process images (up to 4G). The sequence of data does not necessarily follow the physical arrangement of the network nodes.

A master device executes more complex operations like broadcast communication between slaves and multicast, and many more. In IP (Internet Protocol) routing, the EtherCAT protocol may be injected into the UDP (User Datagram Protocol)/ IP datagrams.

The EtherCAT Technology Group

The ETG, or EtherCAT Technology Group, is a worldwide organization where the OEM, technology service providers, and end users collaborate to encourage and support fast-moving technological developments of the EtherCAT. Founded in November 2003, it provides a forum for end users from different organizations. Today, it has bases in China, USA, Korea, and Japan.

Contrary to popular belief, you do not have to be a member of ETG to enjoy EtherCAT. Membership to the ETG is free because the EtherCAT is an open source technology.