What is EtherCAT? from AutomationDirect

What is EtherCAT, and why should you use it for your automation network? EtherCAT is an open-source Ethernet protocol designed for extreme speed, high reliability, and deterministic communication between many devices, on a dedicated linear, or ring topology network. EtherCAT can be used for standard communication from a PLC to another device, high speed and high-fidelity communication such as required for fast response remote I/O, or deterministic coordination such as having multi-axis servo motion from a single controller. TCP based protocols, such as Modbus/TCP, EtherNet/IP, and TCP/IP all use a TCP socket at the base of their packet traffic, and IP addresses to identify different nodes on the network. A TCP switch analyzes every packet it receives for packet fidelity and looks for any data corruption. It then copies any correct packets on to the next drop in the network, while returning corrupted packets to their sender. While this is very useful in larger multi-layered networks where packet collisions and mis-sends are common, it adds a lot of extra time to packet transfer, as the packet undergoes this analysis and copying at every switch it goes through. In an EtherCAT network however, there is minimal packet analysis, and no IP addresses, collision detection or the like. There is a single EtherCAT master, and all of the other devices on the network are nodes. Each node has a unique ID number. There is a single packet sent out by the master, and as it reaches the incoming port on each node, the node only reads information from and writes information to a specific section of the packet before sending the packet from its outgoing port to the next node. Because of this simplistic addressing and data transfer scheme, an EtherCAT packet regularly transits the entire network in a few hundred microseconds. Compare that throughput with a TCP based protocol which takes 20+ milliseconds of transit time for even the simplest networks, and the advantages of EtherCAT come into focus. Furthermore, each node and the master have internal timeclocks. As each node copies information to its section of the packet, it also drops a timestamp in as well. When the packet arrives back at the master, it is able to look at the timestamps for each node in the network and send a requested offset adjustment for each node with the next packet. In this way, the entire network is synchronized to the master’s internal clock with each packet transit. This synchronization allows extreme levels of deterministic control for many applications, including multi-axis motion coordination. Finally, EtherCAT also offers security advantages over an internet connected TCP network. EtherCAT devices often use dedicated interface ports for their interactions, and as such these networks are easily physically separated from the main controls or internet facing network in your architecture. Whether you need extremely fast throughput times, robust and secure communication, or multi-axis motion coordination, EtherCAT has an option for your industrial automation needs! To see more videos on EtherCAT, click here. To take a look at AutomationDirect.com and see many products including EtherCAT masters and nodes, click here. To subscribe to our YouTube channel, click here.