Omron Sysmac NJ Series User Manual page 73

CPU Unit
EtherCAT communications
Cyclic communications (for PDO data)
Device
variables and
Axis Variables*
Message communications (for SDO data)
EC_CoESDORead/
EC_CoESDOWrite
SDO communications:
When required
(from instruction or
Sysmac Studio)
* Device variables for EtherCAT slaves
Process Data Communications (PDO Communications)
PDO communications is used for constant data exchange between the master and slaves. It is called
"process data communications".
PDO data (i.e., I/O data that is mapped to PDOs) that is allocated in advance is input and output peri-
odically each EtherCAT process data communications cycle (i.e., the task period of primary periodic
task or priority-5 periodic task).
It is accessed from the NJ/NX-series CPU Unit in the following ways.
• With device variables for EtherCAT slave I/O
• With Axis Variables for Servo Drive and encoder input slaves to which an axis is allocated
Additional Information
You can use the priority-5 periodic task only with NX701 CPU Units.
SDO Communications
SDO communications are used to read and write specified slave data from the master when required.
This is called "SDO communications".
You can read/write the following specified slave data with the EC_CoESDORead (Read CoE SDO) in-
struction or the EC_CoESDOWrite (Write CoE SDO) instruction.
• SDO data in slaves (parameters, error information, etc.)
NJ/NX-series CPU Unit Built-in EtherCAT Port User's Manual (W505)
Process data communications:
IN
OUT
PDO
data
IN
SDO data
Axis Variables only for Servo Drive and encoder input slaves to which axes are allocated
3 EtherCAT Communications
Constant data exchange
(process data communications cycle)
EtherCAT
PDO
data
OUT
SDO data
3
3-5