Relationship Between Task Periods And Packet Intervals (Rpis) - Omron NJ Series User Manual

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Relationship between Task Periods and Packet Intervals (RPIs)

Effect of Tag Data Links on Task Periods
Tag data transfer is executed as part of the task processing.
Therefore, the tag data transfer process is added to the task processing for tasks set as a tag's re-
freshing task. This requires you to make adjustments to the variable access time and task period in
the Task Settings Tab Page so that these processes are completed within a single task period.
1
Calculate the time required for the data transfer and set the result as the variable access
time(*).
For the formula for calculating the time required for data transfer, refer to Data Processing
Time Overview on page 15-23.
* If the same refreshing task is set for multiple tag sets, calculate the total time required for all tags in tag
sets.
2
Set the variable access time in the Task Setup to a value equal to or greater than the value
calculated in step 1 above.
Adjust the task period time after adding in the time calculated in step 1. Use the Sysmac Studio
to set the variable access time and task period settings.
Refer to NJ/NX-series CPU Unit Software User's Manual (Cat. No. W501) for details.
Adjusting Packet Intervals (RPIs) According to the Task Period
Tag data is transferred based on the actual time required for the transfer (task period × number of data
transfers), regardless of the packet interval (RPI) setting.
Set the packet interval (RPI) as below.
Actual time required for data transfer (Task period × Number of data transfers) < RPI
For details on the actual time required for data transfer, refer to 15-3-2 Built-in EtherNet/IP Port Data
Processing Time on page 15-23.
Example: Relationship between the RPI Setting and the Time Required for Data Transfer
• Task period: 10 ms
• Number of data transfers: 2 times
• Actual time required for data transfer: 10 ms × 2 times = 20 ms
Regardless of the RPI value, the time required for the data transfer is 20 ms.
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User's Manual (W506)
15 Communications Performance and Communications Load
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