5-1
I/O Refreshing
This section describes I/O refreshing for NX Units.
5-1-1
I/O Refreshing from CPU Units to NX Units
An NX-series CPU Unit cyclically performs I/O refreshing with the NX Units.
The following period and two cycles affect operation of the I/O refreshing between the CPU Unit and
the NX Units.
(a) Primary period in CPU Unit
(b) Refresh cycle of the NX bus
(c) Refresh cycle of each NX Unit
CPU Unit
(b) Refresh cycle of the NX bus
NX Unit
NX Unit
(c) Refresh cycle of each NX Unit
NX Unit
(a) Primary
period in CPU
Unit
Data exchange between
the user program and I/O Units
The following operation occurs.
• The refresh cycle of the NX bus in item (b) is automatically synchronized with the primary period of
the CPU Unit in item (a).
• The refresh cycle of each NX Unit in item (c) depends on the I/O refreshing method which is given
below.
Refer to the
NJ/NX-series CPU Unit Software User's Manual (Cat. No. W501)
for detailed information
on I/O refreshing between the CPU Unit and the NX Units.
Refer to
5-1-3 Calculating the I/O Response Time of NX Units
on page 5 - 4 for the I/O response
time of NX Units in a CPU Rack.
5 I/O Refreshing
5 - 2
NX-series Analog I/O Units User’s Manual for High-speed Analog Input Units (W592)
