10 I/O Refreshing
10 - 2
NX-series EtherNet/IP Coupler Unit User’s Manual (W536)
10-1 Introduction to I/O Refreshing for
EtherNet/IP Slave Terminals
This section introduces I/O refreshing for NX-series EtherNet/IP Slave Terminals.
The CJ/CS-series CPU Unit performs I/O refreshing cyclically with the NX Units in an EtherNet/IP Slave
Terminal through EtherNet/IP communications and the NX bus. The following four cycles affect the
operation of I/O refreshing between the CJ/CS-series CPU Unit and the NX Units in an EtherNet/IP
Slave Terminal.
(A) Cycle Time in the CPU Unit
(B) Packet Interval (RPI)
(C) Refresh Cycle of the NX bus = 1.5 ms
(D) Refresh Cycle of each NX Unit
I/O refreshing operates asynchronously between the CJ/CS-series CPU Unit and Slave Terminals. This
is an important function when calculating the I/O response time (refer to 10-2-1 I/O Response Time on
page 10-5 for more information).
The following figure shows the operation of I/O refreshing with an EtherNet/IP Slave Terminal.
Refer to the CS and CJ Series EtherNet/IP Units Operation Manual (Cat. No. W465) for more
information about CJ-series built-in EtherNet/IP port and EtherNet/IP Unit communication per-
formance.
NX Unit
(A) PLC cycle time
EtherNet/IP port
I/O refreshing between the CPU
Unit and NX Units
(B) Packet interval (RPI)
Communications path
Other EtherNet/IP slaves
(D) Refresh cycle of
each NX Unit
(C) Refresh cycle of the NX bus
EtherNet/IP
Coupler Unit
EtherNet/IP Slave Terminal
NX Unit NX Unit
CJ/CS-series CPU Unit
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