Possibly to convert/change data types?
We've implemented our pilot site with Canary using MQTT Collector and noticed that many tags are classified as I8 when they could be I1 or I2. These data types are defined in our Ignition system.
If we change the data types in Ignition while Canary is actively collecting, will Canary update the data types automatically, or would we need to wipe the data and start over? Is it possible to change data types directly in Canary?
Additionally, if a tag is set as I8 but the actual published values are small (e.g., '50' or '1'), does the I8 classification cause unnecessary storage overhead in Canary?
5 replies
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I'm interested to see what Steve says. But I don't think the Historian cares. I've seen a tag switch from float to string (because the field device went wonky) and the Historian took it in stride. I think where it comes into play are client tools like Axiom and Excel Add-In. In the case above, Axiom treated the tag like string even though there were years of Float data and just the latest value was string.
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Hi ,
Assuming the payload is SparkplugB, Sparkplug dictates the data type since it supports a property indicating the data type along with the value. This is determined by the publishing client. You can change the data types on the publishing side and the historian will ingest it.
You wouldn't be able to go back and change data types of historical values, but you could at least correct it going forward. The historian allots space based upon the data type. The space may be negligible if it's not a lot of tags or they don't change often, but it makes sense to change them if you can.
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