Hello, I want to get the tag history for a string array tag type. I am running version 8.3 and would like to use an internal Ignition database, such as the new Core Historian or Legacy Historian. This tag is part of a UDT and has a bidirectional binding to a barcode input component. I checked the UDT and the tag to ensure that history is enabled. A screenshot of the tag editor is shown below.
When I look at my logs, I get the warning message below when the tag changes and the value should be stored in the historian.
I have already tried restarting the tag and UDT, refreshing the providers, and confirmed that my historian is running. I was successful in getting the history when I used other tags of different data types (string and integer) in the UDT.
I noticed there was no tag path under the historical provider when configuring a tag history binding.
The user maual stated that it is possible to get tag history for array types if the OPC server or driver supports it. Unfortunately, it didn’t mention whether the internal historians support this.
I found another post on the forum with a similar issue. The solution was to create a tag for each row. It did not confirm whether an array type is valid for Ignition’s internal historians.
Based purely on the column types documented for the historian, they are not.
I believe what you’re seeing is a known issue. This should be fixed in version 8.3.2 (releasing soon, release candidate available here in the meantime)
For some additional detail: I am running version 8.3.0 on a full Ignition installation. I wanted to test @Dutch_Buckholz’s idea of an older version. I created a string array tag on an 8.1.48 Ignition Edge system.
The string array tag’s history seemed to work at first using the internal Edge historian, as the array rows appeared as individual column paths under the historical provider when configuring a tag history binding.
However, it didn’t seem to capture all the changes.
Then, when checking the logger, I found an error.
Unfortunately, to upgrade to 8.3.2 I need higher authorization. I’ll update when I’m able to try it on 8.3.2.
But seeing how a string array failed to store historical data on 8.1.48, I believe @pturmel ‘s about it not being a valid type is accurate—unless I’m missing some setting or process step that is causing the failure.
The Internal/Core Historian does not store array types as a single object. Instead, each item within the array is processed and stored as a separate atomic value.
This is why your browse results are populated with the array tag path followed by the individual indices (e.g., New Tag[0], New Tag[1], etc.).
As @Dutch_Buckholz mentioned, there was a critical bug fixed in 8.3.2 regarding array storage. In previous 8.3 versions, value changes within an array could be missed or cause unexpected behavior, such as constant retirement on every value change.
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