Introduction To Ethercat; Ethercat Features; Ethercat Communications - Omron Sysmac NJ Series User Manual

1 Introduction
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 communications cycle time by transmitting Ethernet frames at high speed.
Furthermore, even though EtherCAT is a unique protocol, it offers excellent general-purpose applica-
bility. For example, you can use Ethernet cables because EtherCAT utilizes standard Ethernet technol-
ogy for the physical layer. And the effectiveness of EtherCAT can be fully utilized not only in large con-
trol systems that require high processing speeds and system integrity, but also in small and medium
control systems.
1-1-1

EtherCAT Features

EtherCAT provides the following features.
High-speed Communications at 100 Mbps
The I/O response time from signal input to signal output has been significantly reduced. By fully utiliz-
ing the optimized Ethernet frame bandwidth to transmit data using a high-speed repeat method, it is
possible to efficiently transmit a wide variety of data.
1-1-2

EtherCAT Communications

EtherCAT does not send data to individual slave nodes on the network, instead, it passes Ethernet
frames through all of the slave nodes.
When frame passes through a slave node, the slave node reads and writes data in the areas allocated
to it in the frames in a few nanoseconds.
The Ethernet frames 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 realtime data transmission.
EtherCAT master
1-2
Slave
Slave
data
OUT IN
• Output data addressed to the local node is read.
• Input data is written.
Ethernet frames
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)
Slave