Can I use a tag property as a limit line value in a trend chart?
I am reading some into Canary. Each tag has a Special Limit & General Limit value. I want to use these values as limit lines in a trend chart, bar chart, value box etc within asset cards.
I have added the 2 x properties to the OPC Collector and imported correct values into these ‘fields’ (properties) for each tag.
I then want to use this field in my asset cards as a limit line to show if measured values are within such limits. Hopefully a dotted limit line or similar in the same chart as the measured value.
Below shows small snap of asset card showing tag.General Limit and tag.Special Limt. I can’t see a way to use the same values in the trendchart high & low limits. Can (how) do I write to the limit line value in a script?
Perhaps there is a more elegant solution to what I’m trying to achieve here?
3 replies
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Hi Derwyn Oxley ,
There are two possible solutions I see here.
- Create a calculation that outputs the property value. You could use the Property function to do this, but it would consume another tag license. You would then just add that property tag to the chart and set it as the limit.
- Throw the tag on the chart twice. Save it, then edit the AxiomApp2 file under the covers. Similar to how you can display the property of a tag in a value box, you can add the property name at the end of the source tag within this file. In my screenshot below I edited the second tag to display its High Limit property instead of the value. When you reopen the application in Axiom, you'll need to use the TimeAverage aggregate (as opposed to TimeAverage2) because these property values do not have duration. By setting it to TimeAverage, it should extend the last value to the live edge of the chart.
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Steve,
Adding a 2nd tag looks like a fantastic option. I'll take a look this morning. Much appreciated
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Steve, I ran a test on first screen and I now have 2 x additional trend lines showing the 2 x "limit" values correctly. Many thanks again
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