7 SSI Input Units
7 - 14
NX-series Position Interface Units User’s Manual (W524)
7-6 I/O Refreshing Method Setting
There are the following methods to exchange data between SSI Input Units and the Controller:
Free-Run refreshing, synchronous I/O refreshing, and task period prioritized refreshing.
This section describes how to set the I/O refreshing method for SSI Units, the I/O refreshing methods,
and the differences in I/O refreshing methods for different Controllers.
This section describes the settings of the I/O refreshing method for each Communications Coupler Unit.
EtherCAT Coupler Unit
When an SSI Input Unit is connected to an EtherCAT Coupler Unit, the I/O refreshing method
depends on the Enable Distributed Clock setting.
The following table lists the possible combinations.
Unit version 1.2 or later and an NX-ECC203 EtherCAT Coupler Unit are required to use task
period prioritized refreshing. If you use unit version 1.1 or earlier and an NX-ECC203 EtherCAT
Coupler Unit, operation is performed with synchronous I/O refreshing.
EtherNet/IP Coupler Unit
When an SSI Input Unit is connected to an EtherNet/IP Coupler Unit, you can use only Free-Run
refreshing. There is no setting.
The following table lists the refresh cycles for Free-Run refreshing, synchronous I/O refreshing, and
task period prioritized refreshing.
7-6-1 Setting the I/O Refreshing Methods
DC enabled/disabled I/O refreshing method
Enabled (DC for synchronization) Synchronous I/O refreshing
Enabled (DC with priority in cycle time) Task period prioritized refreshing
Disabled (FreeRun) Free-Run refreshing
Refresh Cycle
I/O refreshing method Refresh cycle
Free-Run refreshing
Always 125 μs
*1
*1. The value is always 250 μs for unit version 1.1 or earlier.
Synchronous I/O refreshing
*2
*2. The refresh cycle depends on the specifications of the EtherCAT master and EtherCAT Coupler Unit. It also
depends on the Unit configuration.
250 μs to 10 ms
*3
*3. The range is 250 μs to 4 ms for unit version 1.1 or earlier. The range is also 250 μs to 4 ms for unit version 1.2
or later if you use the NX-ECC201/202 EtherCAT Coupler Unit.
Task period prioritized refreshing
*2
125 μs to 10 ms
To Next Page
Loading...
Need help?
General
