Concurrency Of Tag Data Link Data - Omron Sysmac NJ-series User Manual

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Concurrency of Tag Data Link Data

To maintain the concurrency of data in a tag data link, you must set a refreshing task for each network
variable that is assigned to a tag.
• Maintain concurrency in the tag data in a tag set.
• The timing of updating network variables that are assigned to tags is synchronized with the execution
period of the program that accesses the network variables.
Additional Information
A refreshing task maintains concurrency of the value of a global variable from all tasks that
access that global variable. This is achieved by specifying a single task that can write to that
global variable and not allowing any other task to write to that global variable. For details on
refreshing tasks, refer to the NJ/NX-series CPU Unit Software User's Manual (Cat. No. W501).
 Maintaining Concurrency in the Tag Data in a Tag Set
To maintain concurrency in the values of multiple tags in a tag set, the tags (variables with a Network
Publish attribute) must satisfy the following four conditions.
(1) The tags must be assigned to the same tag set (connection).
(2) A refreshing task must be set for the network variables assigned to the tags, and the
refreshing task must be the same for all tags in the tag set.*
(3) In the case of an NX1P2 CPU Unit and an NJ-series CPU Unit, a tag that uses AT
specification must not be included in the same tag set.
(4) The variable access time set for each task must be set to a higher value than is
required to transfer the tag data. Refer to 14-3-3 Relationship between Task Periods
and Packet Intervals (RPIs) for details on the variable access time and data transfer.
* If you set a refreshing task for a network variable, you must set a variable access time to allocate
enough time to access the network variable from outside of the Controller.
• Setting Refreshing Tasks for Tags (Network Variables)
Concurrency of the tags in the tag set is maintained.
NJ/NX-series Controller
Refreshing task
Value of variable
Variable a 100 10
Variable b 100 10
Variable c 100 10
Additional Information
When using an NX1P2 CPU Unit and an NJ-series CPU Unit, you do not need to set a refreshing
task for variables (tags) that use an AT specification because they are updated in the primary
periodic task.
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User's Manual (W506)
Tag set
Connection
Variable a
Variable b
Tag data links updated.
Variable c
EtherNet/IP
7 Tag Data Link Functions
NJ/NX-series Controller
Refreshing task
Tag set Value of variable
Variable d
Variable e
Variable f
10
The values of the
10
tags in the tag set
are refreshed at
the same time.
10
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