# Tag Change

**URL:** <https://forum.inductiveautomation.com/t/tag-change/4466>\
**Category:** Ignition\
**Created:** [May 14, 2012, 2:08pm UTC](https://forum.inductiveautomation.com/t/tag-change/4466 "2012-05-14T14:08:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mcarangelo](https://avatars.discourse-cdn.com/v4/letter/m/9de053/32.png) [@mcarangelo](https://forum.inductiveautomation.com/u/mcarangelo)\
**Post date:** [May 14, 2012, 2:08pm UTC](https://forum.inductiveautomation.com/t/tag-change/4466/1 "2012-05-14T14:08:18Z")

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I have UDP tag coming in from a scanner. In some cases, the data being transmitted may be exactly the same. I am processing the information on a tag change script. But if a transmit occurs with the same exact data, the script will not fire. Whats the best way to make this work. Can I write a blank string to the tag every time the tag change script fires? I’ve tried  
system.opc.writeValue(“IgnitionOPCUA”, “_VB0_/4000/Field0”, " ")  
but it doesn’t seem to be writing to the tag.

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**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:** [May 14, 2012, 3:51pm UTC](https://forum.inductiveautomation.com/t/tag-change/4466/2 "2012-05-14T15:51:25Z")

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Those field tags are read-only.

There’s a bigger issue at hand here, which is that the OPC-UA subscriptions don’t send data change notifications unless a value change has occurred. Currently, there are no settings available to change that.

Notifications are sent on value or quality changes, not timestamp.