DC enable set-
ting in the
EtherCAT Cou-
pler Unit
NX Units that
support only
synchronous
I/O refreshing
NX Units
that support
only Free-
Run refresh-
ing
NX Units that
support both
Free-Run re-
freshing and
synchronous
I/O refreshing
NX Units that sup-
port Free-Run re-
freshing, synchro-
nous I/O refresh-
ing, and task peri-
od prioritized re-
freshing
NX Units that
support only
time stamp re-
freshing
*1
Enabled (DC for
synchroniza-
tion)
*2
Synchronous
I/O refreshing
Free-Run re-
freshing
Synchronous I/O
refreshing
Synchronous I/O re-
freshing
Time stamp re-
freshing
Enabled (DC
with priority in
cycle time)
*2
Task period priori-
tized refreshing
Disabled (Free-
Run)
*3
Not available.
Free-Run re-
freshing
Free-Run refreshing Operation with
time stamp re-
freshing is not
possible.
*4
*1. Two types of time stamp refreshing are available: one is input refreshing with input changed time and the oth-
er is output refreshing with specified time stamp.
*2. The EtherCAT Slave Terminal operates in DC Mode.
*3. The EtherCAT Slave Terminal operates in Free-Run Mode.
*4. Refer to the manuals for the specific NX Units for details on the operation when the DC is set to Disabled
(FreeRun).
Because the High-speed Analog Input Units support only the synchronous I/O refreshing method, syn-
chronous I/O refreshing is always used.
EtherCAT Coupler Unit is the only Communications Coupler Unit that can be connected to the High-
speed Analog Input Units. Other Communications Coupler Units cannot be connected.
Additional Information
The EtherCAT Slave Terminals with DC enabled and EtherCAT slaves that support DC synchro-
nization execute I/O processing based on Sync0, which is shared over the EtherCAT network.
However, EtherCAT slaves and NX Units support different specifications and performance for
the timing to read inputs and refresh outputs. Accordingly, their timing to read inputs and refresh
outputs is not synchronized.
Refer to the manuals for the EtherCAT slaves for information on the timing to read inputs or to
refresh outputs in EtherCAT slaves.
5-2-3
Restrictions in Refresh Cycles
The refresh cycle for synchronous I/O refreshing of the High-speed Analog Input Units should be with-
in the following limits.
I/O refreshing method
Refresh cycle
125 μs to 32 ms
*1.
The refresh cycle depends on the specifications of the EtherCAT master and EtherCAT Coupler Unit. It also
depends on the Unit configuration.
5 I/O Refreshing
5 - 8
NX-series Analog I/O Units User’s Manual for High-speed Analog Input Units (W592)
