Relationship Between Task Periods And Packet Intervals (Rpis) - Omron NY532-5400 User Manual

13 Communications Performance and Communications Load

13-3-3 Relationship between Task Periods and Packet Intervals (RPIs)

Effect of Tag Data Links on Task Periods
The tag data is transferred during task processing. Therefore, the tag data transfer process is added to
the task processing for tasks set as a tag's refreshing task. This requires you to make adjustments to
the variable access time and task period in the Task Setup 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 the data transfer, refer to Data Processing
Time Calculation Example.
* 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 cal-
culated 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. For details, refer to the NY-series Indus-
trial Panel PC / Industrial Box PC Software User's Manual (Cat. No. W558).
Adjusting Packet Intervals (RPIs) According to the Task Periods
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. Therefore, set the packet interval (RPI)
according to the following guideline.
Actual time required for data transfer (Task period × Number of data transfers) < RPI
For details on the actual time required to transfer data, refer to 13-3-2 Built-in EtherNet/IP Port Data
Processing Time.
Example: Relationship between the RPI Setting and the Time Required for Data Transfer
• Task period: 10 ms
• Number of data transfers: 2
• 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.
RPI of 10 ms
Example: Primary periodic task
OI UPG MC
OI UPG MC
Send data
processing
Task period × 2
Refreshing period
during RPI
10 ms
13-24
OI UPG MC OI UPG MC
(1)
(2)
Task period: 10 ms
Tag data link service
To Controller #2
Time required to transfer data from Controller #1: 20 ms
NY-series Industrial Panel PC / Industrial Box PC Built-in EtherNet/IP Port User's Manual (W563)
OI
UPG
MC
RPI of 20 ms
Example: Primary periodic task
OI UPG MC OI UPG
OI MC
UPG
(1)
Send data
processing
Task period × 2
Tag data link service
Refreshing period
during RPI:
20 ms
I/O refreshing
User program execution
Motion control
Data link processing
(system common processing 3)
MC OI UPG MC
(2)
Task period: 10 ms
To Controller #2