EtherCAT Connection
ZW User's Manual
161
6
Commun
ication
s with Exte
rnal De
vi
ces
Communications Types of EtherCAT
EtherCAT provides the following two types of communication functions.
PDO communications are always updating data per communication cycle on EtherCAT, while SDO
communications are processed in between those updates.
●
Process data communications functions (PDO communications)
This communication function is used to transfer process data in real time in a fixed-cycle.
By mapping logical process data space to each node by the EtherCAT Master Unit, it achieves fixed-cycle
communications among the EtherCAT Master Unit and Slave Units.
●
Mailbox communications functions (SDO communications)
It refers to message communications.
At any timing, the EtherCAT Master Unit transmits commands to Slave Units and the Slave Units return
responses to the EtherCAT Master Unit.
It performs the following data communications:
• Read and write process data
EtherCAT Master Unit
Slave Unit
Ethernet frame
Slave Unit
Slave Unit
Slave Unit
Ethernet
header
EtherCAT
header
1st EtherCAT
datagram
2nd EtherCAT
datagram
3rd EtherCAT
datagram
CRC
. . .
Logic process data
.
.
.
.
.
.
.
.
.
Data a
Data b
Data c
Summary of Contents for ZW-C1*AT
Page 17: ...ZW User s Manual 1 15 ...
Page 54: ...Installing the Sysmac Studio 52 ZW User s Manual MEMO ...
Page 74: ...Operating with Sensor Controller 72 ZW User s Manual MEMO ...
Page 120: ...Setting the System 118 ZW User s Manual MEMO ...
Page 138: ...Controll input signal with PC tool 136 ZW User s Manual MEMO ...
Page 262: ...No protocol Connection 260 ZW User s Manual MEMO ...
Page 271: ...8 Troubleshooting Troubleshooting 8 1 Error Messages 270 8 2 Troubleshooting 284 ...
Page 358: ...Connecting by No protocol Communications 356 ZW User s Manual MEMO ...
Page 449: ......