Omron NX-ECC201, User Manual, Page: 268 / 406

12 Communications Performance
12 - 14 NX-series EtherCAT Coupler Unit User’s Manual (W519)
This section describes the I/O response time for I/O refreshing when the NX Unit operates with
Free-Run refreshing and the EtherCAT Slave Terminal operates in Free-Run Mode. The I/O response
time is the time required for the following processing: The CPU Unit processes an external signal input
to one NX Unit, and another NX Unit outputs the processed result as an external signal.
With Free-Run refreshing, the refresh cycle of the NX bus and the I/O refresh cycle of the NX Units
operate asynchronously. In Free-Run Mode, the NX bus refresh cycle is not synchronized with the pri-
mary period or process data communications cycle. The NX bus operates on its own cycle. Refer to
Section 10 I/O Refreshing for details on the operation of Free-Run refreshing and synchronous I/O
refreshing.
A timing chart for the I/O response time with Free-Run refreshing is provided in the following figure.
This timing chart shows the maximum I/O response time.
12-1-2 I/O Response Times for Free-Run Refreshing
Timing Chart and Configuration Elements of the I/O Response Time
Etxj
Primary periodic task
IO UPG MC IO UPG MC
IO UPG MC
IO UPG MC
Primary period
Tcycle
I/O response time
IO UPG MC
CPU Unit
EtherCAT Slave
Terminal #n
EtherCAT
Coupler Unit
NX Unit (inputs)
Signal to
input terminal
NX Unit (outputs)
Signal from
output terminal
Time lag 2 =
T#n-Free_I/OCycle Time lag 3 =
Tcycle Time lag 4 =
T#n-Free_I/OCycle
Process data
communications cycle
Time lag 1 =
Tnx-InProc
Tnx-Indelay
Tnx-InProc
T#n-InTrans
T#n-Free_I/OCycle
T#n-OutTrans
Tnx-OutProc
Tnx-Outdelay
Time lag 5 =
Tnx-OutProc
EtherCAT
communications path
Primary period
Tcycle
Primary period
Tcycle
Primary period
Tcycle
Primary period
Tcycle
EtherCAT transmission time
EtherCAT
transmission time
EtherCAT transmission time
EtherCAT transmission time EtherCAT transmission time
EtherCAT
Master
Function
Module
PLC
Function
Module
Primary periodic task Primary periodic task Primary periodic task Primary periodic task
Process data
communications cycle
Process data
communications cycle
Process data
communications cycle
Process data
communications cycle