Why can't I access my AOI local tags from my HMI?

A client contacted me this week with a problem. He couldn't get his HMI to communicate to his ControlLogix AOI's local tags.

However, what really seemed weird was that Rockwell HMI projects could do just this. So the question became, what trick was the factory using to make this possible?

I was fairly confident that referencing AOI local tags was do-able, but I thought I remembered there was some setting somewhere to enable it.

After hunting around in the software for awhile, I found the AOI Parameters and Local Tags screen did indeed have some advanced columns that were not displayed by default.

AOI-Parameters-FI

And the column and setting that I was confident was the culprit, external access, defaulted to off.

I selected it so it would be displayed, and found was the Rockwell example had the local tags set to “read/write,” while the clients had defaulted to “none.”

AOI Parameters and Local Tags Read Write Access

At this point it was as simple as changing the external access property from “none” to “Read/Write” and the HMI was now able to access the AOI's local tags.

I hope you've found this article about accessing AOI local tags helpful.

If you have a comment or question, please feel free to share it with us by clicking on the “post a comment or question” link below.

Sincerely,

Shawn Tierney
Automation Instructor and Blogger

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Shawn Tierney

Shawn began sharing automation news and know-how online in 1996 when he launched his first BBS. Then in 1999 he moved to the internet launching ShawnMichael.com, which he later renamed ShawnMTierney.com. In 2013 he moved his automation efforts to a new website, TheAutomationBlog.com, which has since become the most popular independent industrial automation blog on the web.
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2 Blog Comments

    • Good morning edw1983,

      I totally agree!

      You know, I’ve never even tried – sounds like it doesn’t work 🙁

      Sincerely,

      Shawn Tierney

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