I/O Response Times For Free-Run Refreshing - Omron NX-ECC201 User Manual

12 Communications Performance

12-1-2 I/O Response Times for Free-Run Refreshing

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.
Timing Chart and Configuration Elements of the I/O Response Time
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.
Primary period
Primary periodic task
PLC
Function
Module
IO
EtherCAT
Master
communications cycle
Function
Module
EtherCAT transmission time
EtherCAT
communications path
EtherCAT Slave
Time lag 2 =
Terminal #n
T#n-Free_I/OCycle
EtherCAT
Coupler Unit
Time lag 1 =
Tnx-InProc
NX Unit (inputs)
Signal to
input terminal
Tnx-Indelay
NX Unit (outputs)
Signal from
output terminal
12 - 14
Primary period
Tcycle
Tcycle
Primary periodic task
IO UPG MC
UPG MC
Process data Process data
communications cycle
EtherCAT transmission time
Time lag 3 =
Tcycle
T#n-InTrans
Tnx-InProc
Primary period
Primary period
Tcycle
Primary periodic task Primary periodic task
IO
IO UPG MC
Process data
communications cycle communications cycle
EtherCAT transmission time
EtherCAT
transmission time
Time lag 4 =
Tcycle + Edelay + Etxj
T#n-Free_I/OCycle
T#n-Free_I/OCycle
T#n-OutTrans
Tnx-OutProc
I/O response time
NX-series EtherCAT Coupler Unit User's Manual (W519)
Primary period
Tcycle Tcycle
Primary periodic task
UPG MC IO UPG MC
Process data Process data
communications cycle
EtherCAT transmission time
Time lag 5 =
Tnx-OutProc
Tnx-Outdelay