The Tech Blog

So EtherCAT is a relatively new(2003) cool bit of industrial Ethernet protocol designed for real-time control and automation applications. Its fundamental goal was to apply Ethernet to applications that need very short update intervals of less than 100us for let’s say fast sensor readings. It uses the same physical layer(2 wires) of Ethernet with normal Cat5 cabling. The EtherCAT data frame embeds its payload in a standard Ethernet frame.

It has a master-slave architecture with the master sending a single frame (called a telegram) that passes through each node in the network. Each EtherCAT slave/node device reads the data addressed to it and inserts its data into the frame as the frame is moving downstream. The telegram moves across the network (let’s say in a ring topology) to all the nodes and returns to the master. This is where it’s much faster compared to Ethernet where it will be point-to-point. Think of it like a train with empty bogies running through a network where each node takes the data it needs and puts in the data it needs to send to the master. So technically in a single frame master can get info from all the nodes in one go.

So on hardware for all nodes, you will need(most of the time) two ethernet ports, one more input, and one for output to daisy chain to other downstream nodes. These slave/node devices have an EtherCAT Slave Controller (ESC) that does “processing on the fly” on the hardware itself enabling faster communication compared to Ethernet. Another great feature is that the master sends a special EtherCAT datagram at short intervals, in which the EtherCAT slave with the reference clock enters its current time. This information is then read from the same datagram by all other EtherCAT slaves featuring a slave clock. It ensures precise synchronization across devices, solving problems related to clock-shifting between the master and the devices.

EtherCAT is definitely gaining traction in industrial automation domains because of its speed. If you’re considering diving into projects within this sector, it’s worth spending the time to learn it.