# ExampleDevice : onDataItemsModified?

**URL:** <https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057>\
**Category:** Module Development\
**Tags:** ignition81\
**Created:** [February 28, 2025, 3:58pm UTC](https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057 "2025-02-28T15:58:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\
**Post date:** [February 28, 2025, 3:58pm UTC](https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057/1 "2025-02-28T15:58:00Z")

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in the ExampleDevice, I don't understand when the "onDataItemsModified" is triggered when I add/delete/rename tags in Ignition ?

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [February 28, 2025, 4:00pm UTC](https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057/2 "2025-02-28T16:00:53Z")

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It's called when an OPC UA client calls the ModifyMonitoredItems service and modifies e.g. the sampling interval, queue size, ~~monitoring mode~~ , filter, etc...

Most things you do in Ignition result in the item being deleted and created on another subscription.

I think only the OPC UA specific Tag Group properties will result in a modify call.

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<div class="post-metadata">

**Author:** ![mazeyrat](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/mazeyrat/32/10955_2.png) [@mazeyrat](https://forum.inductiveautomation.com/u/mazeyrat)\
**Post date:** [February 28, 2025, 4:06pm UTC](https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057/3 "2025-02-28T16:06:36Z")

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When I change Tag group in Ignition it seems to trigger

onDataItemsDeleted  
onDataItemsCreated  
onMonitoringModeChanged

I never see logs for "onDataItemsModified" ?

I wan't to keep track of subscription on the same item to dynamically create opcua node, and delete them where there is no more subscription on it

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<div class="post-metadata">

**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [February 28, 2025, 4:07pm UTC](https://forum.inductiveautomation.com/t/exampledevice-ondataitemsmodified/103057/4 "2025-02-28T16:07:10Z")

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As I said, it's not expected in most cases.