QUANTUM X CX27, Руководство по эксплуатации

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HBM QuantumX
5 EtherCAT
5.1 Basic principles
EtherCAT (Ethernet for Control Automation Technology) is an open and standardized
fieldbus system, characterized by a high performance capability and corresponding in
principle to a specifically adapted Ethernet solution (standard: IEC/FDIS 61158):
EtherCAT uses Ethernet Frames as defined in IEEE 802.3 and supports the use of other
Ethernet protocols in the same network.
End users of EtherCAT have banded together in the EtherCAT Technology Group (ETG) to
support and promote EtherCAT technology
(www.ethercat.org).
EtherCAT replaces the classic Ethernet hubs and switches star topology (although this can
still be used) with an easy-to-cable line topology. Branches or stub lines are supported. The
grouping here is usually one master and additional slaves.
MX840 MX ...
FireWire EtherCAT
Master
IN
OUT
CX27
Fig.5.5: Example: CX27 Gateway to EtherCAT, modules connected via FireWire
5.2 Principle of operation
In contrast to standard Ethernet, the Ethernet Frames from the slaves are processed in
passing (IN and OUT sockets). The standard Ethernet Frame sent by the master (as per
IEEE 802.3) is not first received, then interpreted and the process data copied at every
interconnection, as is the case with other industrial Ethernet solutions. The EtherCAT slave
devices read the data relevant to them as the telegram passes through the device. Input data
are also inserted into the telegram in passing. So a frame is not fully received before being
processed, the processing starts as early as possible. Sending also occurs with a minimal
time offset of just a few bits. The master relies on a standard Ethernet controller.