Synchronous Input Refreshing - Omron NX-ID User Manual

5 I/O Refreshing
Settings
Add NX Units that support Free-Run refreshing to the CPU Unit configuration or Slave Terminal
configuration.
After you add the NX Units, set an I/O refreshing method depending on the connected CPU Unit or
Communications Coupler Unit so that these NX Units operate with Free-Run refreshing.
Refer to 5-2-2 Setting the I/O Refreshing Methods on page 5-7 for information on how to set an I/O
refreshing method.
5-2-5

Synchronous Input Refreshing

The I/O refreshing method described below. Among Slave Terminals, this refreshing method is sup-
ported only by EtherCAT Slave Terminals.
• The timing to read inputs is synchronized on a fixed interval between more than one NX Unit con-
nected to a CPU Unit.
• The timing to read inputs is synchronized on a fixed interval between more than one NX Unit on more
than one Slave Terminal.
This method is used when the problem such as input timing jitter or offset of timing to read inputs
between more than one NX Unit happens.
Description of Operation
CPU Unit Operation
The following describes the operation of synchronous input refreshing between the NX-series
NX1P2 CPU Unit and the NX Units.
• All Digital Input Units and Analog Input Units that are connected to the CPU Units and operate
with synchronous input refreshing read their inputs at the same time at a fixed interval based on
the synchronization timing. (Refer to (a) in the figure below.)
• The CPU Unit reads the input values, which are read by the Unit at the timing of reading inputs, at
immediate I/O refreshing. (Refer to (b) in the figure below.)
• The interval of I/O refreshing varies with the processing conditions of the CPU Unit. (Refer to (c) in
the figure below.) The timing to read inputs will be at a fixed interval. (Refer to (d) and (e) in the
figure below.)
• The timing of reading inputs, the synchronization timing, and the maximum NX bus I/O refresh
cycle are automatically calculated by the Sysmac Studio according to the input refresh cycles of
the NX Units on the CPU Unit when a Unit configuration in the CPU Unit is created and set up.
• In order to read input values correctly, you must determine the inputs before the total of the
ON/OFF response time and input filter time from the timing to read inputs for each NX Unit. (Refer
to (f) in the figure below.)
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NX-series Digital I/O Unit User's Manual (W521)