# Cannot read some tags inside Rockwell AOI

**URL:** <https://forum.inductiveautomation.com/t/cannot-read-some-tags-inside-rockwell-aoi/38393>\
**Category:** Ignition Early Access\
**Created:** [September 4, 2020, 11:09am UTC](https://forum.inductiveautomation.com/t/cannot-read-some-tags-inside-rockwell-aoi/38393 "2020-09-04T11:09:49Z")\
**Posts on this page:** 1\
**Showing post:** 18

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [November 30, 2020, 1:41am UTC](https://forum.inductiveautomation.com/t/cannot-read-some-tags-inside-rockwell-aoi/38393/18 "2020-11-30T01:41:27Z")

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> [@jlandwerlen](#):
>
> I’m assuming nothing?

I use first scan rungs where applicable. Habit, as older Logix versions didn't have default values either, and I try to create AOIs for the least common denominator.

Just to be crystal clear: I am a big fan of Add-on Instructions. I just work around this particular gotcha by moving "public" data into a separate UDT that is passed to the AOI as an in/out parameter.

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