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8 EtherCAT Communications
NX-series EtherCAT Coupler Unit User’s Manual (W519)
8-4 Process Data Objects (PDOs)
8
8-4-1 Introduction
8-4 Process Data Objects (PDOs)
Process data objects (PDOs) are used to transfer data during cyclic communications in realtime.
There are two types of process data objects (PDOs): the RxPDOs, which are used by the EtherCAT
Slave Terminal to receive data from the EtherCAT master; and the TxPDOs, which are used by the
EtherCAT Slave Terminal to send data to the EtherCAT master.
The EtherCAT application layer can hold more than one object to enable the transfer of various process
data of the EtherCAT Slave Terminal.
The contents of the process data is defined in the PDO mapping objects.
EtherCAT Slave Terminals support PDO mapping for I/O control.
8-4-1 Introduction
TxPDO
EtherCAT master EtherCAT
Slave
Terminal
RxPDO
Output data and motion
commands to NX Units
(Output Units)
Status of EtherCAT Slave
Terminals and input data
from NX Units (Input Units)
Example: Built-in
EtherCAT
port on
NJ-series
CPU Unit
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