Omron NX-ECC201 User Manual page 41

1 EtherCAT Networks
The data exchanges that are cyclically performed between the EtherCAT master and EtherCAT slaves
use EtherCAT telegrams that are stored directly in the Ethernet frames.
Each EtherCAT telegram consists of a telegram header (including the data length and one or more
slave addresses), data, and a working counter (i.e., check bits).
If you think of an Ethernet frame as a train, the EtherCAT telegrams would be the cars of the train.
Ethernet frame
1
Ethernet
Ethernet data (1,498 bytes max.)
CRC
header
1st to nth EtherCAT telegrams
EtherCAT frame
EtherCAT
header
1st EtherCAT 2nd EtherCAT . . . . .
nth EtherCAT
telegram telegram
telegram
Telegram
WKC
Data
header
WKC: Working counter
1 - 3
NX-series EtherCAT Coupler Unit User's Manual (W519)