Datalogic AMT58 Series Manual page 142

AMT58x-EC EtherCAT®
6.1.4 Line Termination
EtherCAT network needs no line termination because the line is
terminated automatically; in fact every Slave is able to detect the
presence of downstream Slaves.
An EtherCAT Slave is able to detect the presence of the signal in the
outgoing line (Port 0) or in the return line (Port 1).
If the Slave is not able to detect the signal in its return line then it
closes the communication ring by short-circuiting the TX signal of its
outgoing line with the RX signal of its return line; in this way a
telegram received through the outgoing line is processed and sent
back through the TX of the return line.
The Slave sends a "carrier signal" or a telegram on TX of the
outgoing line continuously and, once the next Slave is connected
again, a signal on RX of the return line is detected again; so the short
circuit is removed and the telegrams are sent on TX of the outgoing
line.
6.1.5 Addressing
It is not necessary to assign a physical address to the device (for
instance using a dip-switch) because the addressing of the Slave is
automatic at power on during the initial scanning of hardware
configuration.
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