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What is EtherCat?


By Unblocked Hub

August 3, 2022

EtherCAT is Ethernet for control and automation technology. It is an Ethernet based technology. And it was developed specifically with industrial automation in mind. EtherCAT uses standard frames as well as the physical layer as defined in the IEEE 802.3 Ethernet standard. However, it addresses some concerns about industrial automation. For example: minimum data requirements for each device, fast response times and implementation costs.

Ethernet is not a practical solution for many industrial applications because it routes data frames to and from many separate addresses. Node-specific routing requires large bandwidth. Because data packets are transported when the host or client requests the data.

EtherCAT, in contrast, uses the same physical and data link layers. Ethernet can route data from many different nodes. In a master/slave configuration, sending and receiving occurs based on requests. The master sends data via EtherCAT. A single frame for the entire network of nodes passes through each node. The master is the only node allowed to send frames. This approach helps in real-time operation and avoids latency.

Each EtherCAT device processes the data frame associated with it in its hardware/software and adds the data to the data frame as it passes through the network.

EtherCAT networks do not require external switches in the network. Each EtherCAT device typically has two ethernet ports. The first port connects to the receiving port or cable of the previous node, and the second port connects to the next node in the network. Instant processing of data in the device's hardware is a significant advantage of EtherCAT. Although there is still a small delay in the data frame, it is greatly reduced with EtherCAT's typically single data stream as you add device data to it.

Many devices may not be able to handle these extremely low cycle times. And the EtherCAT network may need to be slowed down to accommodate these devices. This is also an advantage. EtherCAT also uses a distributed clock system. This method allows low vibration without additional hardware.

As the EtherCAT frame passes through each node, it adds a “message received” timestamp to the node data. Each node adds its timestamp when receiving a message, and then adds a timestamp as the frame travels back through the nodes.

EtherCAT's true ring topology and distributed clock mechanism provide more accurate data with every data transmission. Yet another advantage comes in the form of network topology. Many different network topologies can be used within an EtherCAT network. Since Ethernets use full duplex layers, the EtherCAT slave automatically returns the frame.

Ethernet's star topology is simple and usable. However, EtherCAT networks can extend beyond this with a tree, line. It can be used in a fieldbus type system. It provides incredible flexibility for the EtherCAT network using Ethernet hardware. To get the best result, you should research which type of topology is good for your application.