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.
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.”
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.
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