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

The Automation School - HMI Basics - Article Banner
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, please consider making a pledge to our kickstarter campaign to produce affordable automation training DVD’s at http://www.LinkToKS.com.

Sincerely,

Shawn Tierney
Automation Consultant
Insights In Automation

Did you find my article helpful? Why not become a Premium Member with a small donation, and in return I'll give you a coupon for $10 of automation downloads! Find out more here

The Automation School - HMI Basics - Article Banner

Check Also

theautomationblog-e05-fi

Duplicating Programs in RSLogix and Studio 5000

In today’s article I cover how to quickly and easily export and import programs in RSLogix and …

theautomationschool-pac-basics-lesson-5-2

New ControlLogix Lessons Added!

The Allen-Bradley ControlLogix Programmable Automation Controller platform is a powerful and versatile programmable controller line. …

theautomationblog-e04-fi

Duplicating Routines in RSLogix and Studio 5000

In today’s article I cover how to quickly and easily export and import routines while at the same …

Legacy Comments

  1. It would be even more interesting if nested AOIs could also be accessed from the HMI.

    • Good morning edw1983,

      I totally agree!

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

      Sincerely,

      Shawn Tierney

Leave a Reply