Leuze electronic MSI 400 Series Manual page 152

EtherCAT Gateway
Unlike traditional Ethernet communications, in EtherCAT the I/O data are exchanged at 100MBit/s in full
duplex mode, while the telegram passes through the coupler. Since in this way a telegram reaches lots of
devices in the transmit and receive direction, EtherCAT has a useful data rate of over 90%.
The EtherCAT protocol, optimized for process data, is transported directly in the Ethernet telegram. In turn,
this can consists of several sub-telegrams, each serving one memory area of the process image.
Transmission medium
EtherCAT uses Ethernet as the transmission medium. Standard CAT5 cable is used. Cable lengths of up to
100m between 2 devices are possible.
Only EtherCAT components may be used in an EtherCAT network. To implement topologies deviating from
the linear structure corresponding EtherCAT components are required that support this. It is not possible to
use hubs.
Communication principle
In EtherCAT the master sends a telegram to the first device. This extracts the data intended for it from the
data flow, inserts its response data into the telegram and sends the telegram on to the next device. The
next device processes the telegram in the same way.
If the telegram has reached the last device, this recognizes that no more devices are connected and sends
the telegram back to the master. In this way the telegram is sent via the other pair of wires through all
devices to the master (full duplex). The connection sequence and the use of full-duplex technology means
EtherCAT is a logical ring.
Leuze electronic MSI 400 152