Datalogic AMT58 Series Manual page 139

AMT58x-EC EtherCAT®
6 - EtherCAT® interface
6.1 Basic Information on EtherCAT® Protocol
EtherCAT protocol is designed to use the standard Ethernet
dataframes for issuing data; in addition, and as regards the
hardware, it is not necessary to install dedicated Masters for
establishing and managing the EtherCAT communication because
standard Ethernet network cards can be used. This results in an
advantage in terms of lower costs and simplicity of use because
Ethernet network cards are used in standard personal computers and
are easily commercially available.
An EtherCAT bus can be viewed as a single and large Ethernet
device that receives and sends Ethernet telegrams; it can be
considered an Ethernet subnet supported by an Ethernet dataframes
structure.
However this "subnet" must be fitted with one only EtherCAT Master
controller and several EtherCAT Slaves, but no Ethernet controller
with downstream microprocessor must be present.
Here follows an Ethernet frame structure with EtherCAT:
Inside the Ethernet frames data are transmitted among Master and
Slaves using PDO (process data objects) protocol. Each PDO
message has inside one or more addresses for issuing data to
Slaves; data + address/es (and additional elements such as a
validation checksum) joined together forms an EtherCAT telegram
(Datagram).An EtherCAT frame can contain several telegrams and
often a complete control cycle requires more than one frame.
30