MICRO-EPSILON combiSENSOR 64x0, Инструкция по эксплуатации

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Appendix| EtherCAT Documentation
combiSENSOR 6430
A 2 EtherCAT Documentation
EtherCAT® is, from the Ethernet viewpoint, a single, large Ethernet station that transmits and receives Ether-
net telegrams. Such an EtherCAT system consists of an EtherCAT master and up to 65535 EtherCAT slaves.
Master and slaves communicate via a standard Ethernet wiring. On-the-fly processing hardware is used in
each slave. The incoming Ethernet frames are directly processed by the hardware. Relevant data are ex-
tracted or added from the frame. The frame is subsequently forwarded to the next EtherCAT® slave device.
The completely processed frame is sent back from the last slave device. Various protocols can be used in the
application level. CANopen over EtherCAT technology (CoE) is supported here. In the CANopen protocol, an
object tree with Service Data Objects (SDO) and Process Data Objects (PDO) is used to manage the data.
Further information can be obtained from ® Technology Group (www.ethercat.org) or Beckhoff GmbH, (www.
beckhoff.com).
A 2.1 Preamble
A 2.1.1 Structure of EtherCAT®-Frames
The transfer of data occurs in Ethernet frames with a special Ether type (0x88A4). Such an EtherCAT® frame
consists of one or several EtherCAT® telegrams, each of which is addressed to individual slaves / storage
areas. The telegrams are either transmitted directly in the data area of the Ethernet frame or in the data area
of the UDP datagram. An EtherCAT® telegram consists of an EtherCAT® header, the data area and the work
counter (WC). The work counter is incremented by each addressed EtherCAT® slave that exchanged the cor-
responding data.
Ethernet frame 0x88A4
OR
UDP/IP 0x88A4
Destination Source EtherType
Destination Source EtherType
1. EtherCAT datagram 2. EtherCAT datagram ... Ethernet-CRC Frame header
1. EtherCAT datagram 2. EtherCAT datagram ...
EtherCAT header
(10 byte) Data
(min 32 byte) Working counter
(2 byte) Length
(11 bit) Resolution
(1 bit) Type
(4 bit)
Ethernet-CRC Frame header IP header UDP header
Fig. 24 Setup of EtherCAT frames