Lenze EtherCAT control technology - Manual (Page 18)

Control technology | EtherCAT communication manual
The Lenze control system with EtherCAT
Brief description of EtherCAT
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DMS 3.1 EN 01/2011 TD17
4.1.3 Communication
Compared with the conventional Ethernet, the collision-free transfer of telegrams on the
bus makes EtherCAT a real-time capable bus system.
Communication is always initiated by the EtherCAT master, i.e. the industrial PC. A
telegram sent by the master passes through all EtherCAT slaves. The last slave of the
communication chain sends the telegram back to the EtherCAT master. On the way back,
the telegram is directly sent to the EtherCAT master, without being processed in the slaves.
With EtherCAT, telegram processing completely takes place on the hardware level. The
slaves take the data intended for them from the Ethernet frame and write their data back
to the Ethernet frame. Every datagram can be passed on with a minimum delay.