Omron sysmac NX102-9 Series Owner's Manual page 183

 Synchronizing the Update Timing of Network Variables (Tags) with the User
Program Execution Period
To have the values of network variables (tags) updated to the latest tag data values each time the
user program that accesses those network variables is executed, set the refreshing task for the net-
work variables (tags) to the same type of the task as for the user program that accesses the network
variables (tags).
The difference between the operation of tags with a refreshing task that is the same as the user pro-
gram and tags without a refreshing task is described below.
• Tag (network variable) with a refreshing task
The tag is refreshed each time the program with the task that is set as the refreshing task is exe-
cuted.
• Tag (network variable) without a refreshing task
The tag is refreshed by the system service.
Refreshing is not synchronized to the execution timing of the program.
The diagram shows the refreshing timing of network variables for each CPU Unit.
• NX701 CPU Units
• The tag data link service is executed without being affected by the tasks and system services.
• The system services are executed at the required time without being affected by the tasks
and tag data link service.
Execution
Primary period
priority
High
Primary
periodic task
Priority-16
periodic task
Tag data link
service
Priority-17
periodic task
System service
Low
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User's Manual (W506)
(1) Execution timing of the program
(2) Refresh timing of network variables (tags) with the primary periodic task set as the refreshing task*
(3) Refresh timing of network variables (tags) that do not have the primary periodic task set as the refreshing task
(1) (2) (1) (2)
IO UPG MC IO UPG MC
Task period
IO UPG
(2)
(3)
Tag data is read
UPG
from the tag set.
*: Refreshed during system common processing 2 in the task processing.
7 Tag Data Link Functions
(1) (2) (1) (2)
IO UPG MC IO UPG MC
Task period
Pausing
System services are executed any time when there is no
influence from tasks and tag data links.
(3)
(1) (2)
IO UPG MC
IO UPG
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