Ethercat Connections; Introduction To Ethercat - Omron SYSMAC FH Series User Manual

2 Methods for Connecting and Communicating with External Devices
2-1

EtherCAT Connections

This section describes the communication settings , communication specifications, input/output for-
mats, and the communication timing chart required for communications by EtherCAT between the
Sensor Controller and an external device.
2-1-1

Introduction to EtherCAT

EtherCAT (Ethernet Control Automation Technology) is a high-performance industrial network system
that enables faster and more efficient communications based on Ethernet.
Each node achieves a short communication cycle time by transmitting Ethernet frames at high speed.
Although EtherCAT is a unique communication protocol, standard Ethernet technology is used for the
physical layer, which means you can use Ethernet cables for wider applications.
And the effectiveness of EtherCAT can be fully utilized not only in large control systems that require
high processing speeds and system integrity, but also in small and medium control systems
How EtherCAT Works
In EtherCAT communication, Ethernet frames pass through all of the slave nodes.
When a frame passes through a slave node, the slave node reads and writes the data in the area that
is allocated to it in the frame in a few nanoseconds.
The Ethernet frames that are transmitted by the EtherCAT master pass through all EtherCAT slaves
without stopping. The last slave returns all of the frames, which again pass through all of the slaves
before returning to the EtherCAT master.
This mechanism ensures high speed and real-time data transmission.
EtherCAT master
The data exchanges that are cyclically performed between the EtherCAT master and EtherCAT slaves
use EtherCAT telegrams that are stored directly in the Ethernet frames.
Each EtherCAT telegram consists of a telegram header (including the data length and one or more
slave addresses), data, and a working counter (i.e., check bits).
2 - 4
Slave Slave
Data
OUT
IN
• The slave reads output data addressed to it.
• The slave writes input data.
Ethernet frames
FH/FHV Series Vision System User's manual for Communication Settings (Z342-E1)
Slave