1 - 3
1 Features and System Configuration
CJ-series EtherCAT Slave Units Operation Manual (W541)
1-1 Introduction to EtherCAT
1
1-1-2 Types of EtherCAT Communications
The following 2 types of communications are available with EtherCAT.
PDO communications are executed in each EtherCAT communications cycle to refresh data continu-
ously. SDO communications are executed between PDO communications.
PDO communications transfers process data cyclically and in realtime.
The EtherCAT master maps the logical process data space to the nodes to achieve cyclic communica-
tions between the EtherCAT master and slaves.
1-1-2 Types of EtherCAT Communications
Process Data Communications (PDO Communications)
Ethernet
header
CRC
Ethernet data (1,498 bytes max.)
Data
Header
WKC
1st to nth EtherCAT datagrams
EtherCAT
header
1st EtherCAT
datagram
2nd EtherCAT
datagram
nth EtherCAT
datagram
. . . . .
EtherCAT frame
Ethernet frame
WKC: Working counter
To Next Page
Loading...
Need help?
General
