5-1-2
I/O Refreshing from CPU Units or Industrial PCs to Slave Termi-
nal
The CPU Unit or the Industrial PC cyclically performs I/O refreshing with the Slave Terminal through
the Communications Master Unit and the Communications Coupler Unit.
The following four cycles affect operation of the I/O refreshing between the NX Unit on a Slave Termi-
nal and the CPU Unit or Industrial PC.
(a) Cycle time of the CPU Unit or Industrial PC
(b) Communications cycle of the host network
(c) Refresh cycle of the NX bus
(d) Refresh cycle of each NX Unit
Data exchange between the
user program and I/O Units
Communications Master Unit
CPU Unit or
Industrial PC
(a) Cycle
time
(b) Communications cycle of the host network
(c) Refresh cycle of the NX bus
Communi-
cations
Coupler
Unit
NX Unit
NX Unit
NX Unit
Communications path
Other communications
slaves
(d) Refresh cycle of each NX Unit
Slave Terminal
The cycle time of the CPU Unit or Industrial PC and communications cycle of the host network and the
I/O refresh cycle of the NX bus are determined by the CPU Unit or Industrial PC types and the com-
munications types.
The following explains operations when the built-in EtherCAT port on the NJ/NX-series CPU Unit or
NY-series Industrial PC is used for communications with an EtherCAT Slave Terminal, with symbols in
the figure.
Refer to the user’s manual for the connected Communications Coupler Unit for details on the opera-
tion of I/O refreshing on Slave Terminals other than EtherCAT Slave Terminals.
Refer to the
NX-series EtherCAT Coupler Units User’s Manual (Cat. No. W519)
for detailed informa-
tion on I/O refreshing between the built-in EtherCAT port and EtherCAT Slave Terminals.
In addition, refer to
5-1-3 Calculating the I/O Response Time of NX Units
response time of NX Units on Slave Terminals.
5 I/O Refreshing
5 - 3
NX-series Analog I/O Units User’s Manual for High-speed Analog Input Units (W592)
5-1 I/O Refreshing
5
5-1-2
I/O Refreshing from CPU Units or Industrial PCs to Slave T
erminal
