Omron NX-OD5256 User Manual

5 I/O Refreshing
5 - 2
NX-series Digital I/O Unit User’s Manual (W521)
5-1 I/O Refreshing for Slave Terminals
This section describes I/O refreshing for NX-series Slave Terminals.
The CPU Unit cyclically performs I/O refres
hing with the Slave Terminal through the Communications Master
and Communications Coupler Units.
There are the following four cycles that affect I/O refresh operations between the NX Unit on a Slave
Terminal and the CPU Unit.
(a) Cycle time of the CPU Unit
(b) Communications cycle of the host network
(c) Refresh cycle of the NX bus
(d) Refresh cycle of each NX Unit
The cycle time of the CPU Unit and communications cycle of the host network and the I/O refresh cycle
of the NX bus are determined by the CPU Unit types and the communications types.
The following shows the operation of I/O refreshing when the built-in EtherCAT port on the NJ-series
CPU Unit is used for communications with an EtherCAT Slave Terminal.
• The process data communications cycle in item (b) and the refresh cycle of the NX bus in item (c)
*1
are automatically synchronized with the primary period of the CPU Unit in item (a).
• The refresh cycle of each NX Unit in item (d) depends on the I/O refreshing method which is given
below.
*1. This applies when the distributed clock is enabled in the EtherCAT Coupler Unit.
5-1-1 I/O Refreshing from CPU Unit to Slave Terminal
Data exchange between the
user program and I/O Unit
Communications Master UnitCPU Unit
(a) Cycle
time
(b) Communications cycle of the host network
(c) Refresh cycle of the NX bus
Communi-
cations
Coupler
Unit
NX UnitNX UnitNX Unit
Communications path
Other communications
slaves
(d) Refresh cycle of each NX Unit
Slave Terminal

Omron NX-OD5256 Specifications

General

Brand	Omron
Model	NX-OD5256
Category	I/O Systems
Language	English