1 EtherCAT – General information
1.2 Protocol properties
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XN-312-GW-EC gateway
07/20 MN050010-EN Eaton.com
A pure EtherCAT system is created when direct communications are estab-
lished without a switch.
Figure 1:
EtherCAT master and nodes
a
Controller with EtherCAT master
b
EtherCAT segment
c
EtherCAT node 1
d
EtherCAT node 2
e
EtherCAT node 3
f
EtherCAT node 4
g
EtherCAT node 5
h
If the RJ45 X2 port (EtherCAT OUT) on the last EtherCAT node is not connected to anything, the node
will internally connect the incoming Rx signal to Tx and send it back to the EtherCAT master this way.
1.2 Protocol properties
The EtherCAT protocol, which is optimized for process data, is encapsulated
within a standard Ethernet frame with the use of a specific EtherType
(0x88A4). Other Ethernet protocols are tunneled fully transparently when
using EtherCAT.
Figure 2:
EtherCAT: Standard Ethernet frame as defined in IEEE 802.3
An EtherCAT frame contains one or more datagrams and can be made up of
multiple subframes so as to transmit large amounts of data.
①
②
③
④
⑤
⑥
⑦
⑧
TX
RX
RX
TX
TX
RX
RX
TX
TX
RX
RX
TX
RX
TX
TX
RX
RX
TX
TX
RX
RX
TX
