Couplers; Network Communication; Communication Principle; Addressing - WAGO I/O-SYSTEM 750 Manual

142 Fieldbus Communication
10.1.2.3

Couplers

For the star topology, the classic Ethernet structure, switches can be optionally
used as couplers.
The use of routers enables communication with an additional sub-network.
10.1.3

Network Communication

10.1.3.1

Communication Principle

The EtherCAT
through a special Ethertype (0x88A4).
The communication principle can therefore be clearly compared using a telegram
train of 100 Mbit/s that drives through the transmission lines and never stops.
The EtherCAT
like passengers. The passengers can thus be individual bits or also several
bytes. The sub-telegrams embody the individual train cars and have varying
lengths. The passengers (data) jump onto or off of the moving train at specific
stations, that is, fieldbus nodes. Entry and exit of the train occurs "on the fly". The
telegram train is only delayed by a few nanoseconds in each case. In addition,
counters in the train are updated based on the exchange.
An exchange within a fieldbus node only occurs, however, if this node is
addressed.
From the point of view of each fieldbus node, the telegram as a whole is not
seen. Instead, the entire telegram runs by a type of viewing window in the
fieldbus node, which continually observes the telegram. The data exchange takes
place immediately, as soon as the station address is recognized.
10.1.3.2

Addressing

The physical order of the Ethernet I/O modules in the network is not relevant to
the data link order or to the addressing. Addresses can be freely selected.
EtherCAT
addresses. In a pure EtherCAT
participant addressing or external switches.
The addressing remains constant, even during subsequent changes, and
therefore does not require manual setting. An EtherCAT
maximum total of 65535 participants.
The slaves can communicate with each other using broadband, multicast, and
cross communication.
If communication occurs between control computers and EtherCAT
one and the same subnet, the transmission is set directly to Ethernet Frames.
Manual
Version 1.2.1
750-354/000-001 EtherCAT® Fieldbus Coupler, ID Switch

fieldbus uses data transmission via standard Ethernet Frames
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data are conveyed on this train (that is, in the Ethernet Frame)
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uses an implicit addressing. Slaves are automatically assigned
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network, there is therefore no need for manual
WAGO-I/O-SYSTEM 750

network can have a
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devices in