I have a 'double' data type tag which has a format of 2 decimal places, which has an 'Above Setpoint' alarm enabled.
When the tag has a value of 22.68 and I set an alarm threshold of 20.5, the alarm appears in the Perspective Alarm Status table.
The tag itself shows a trigger value of 23.4 in its alarm EventValue property, however in the Perspective Alarm Status table object the 'Event Value' column for the alarm displays a value of 23.399999618530273
Is this correct behaviour for the Event Value column, or is there a way of formatting data in the Event Value column to show only 2 decimal places?
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I had an idea on this. I'm not sure how practical it is for your usage case, but I was able to achieve the desired effect by moving the alarm to a derived tag or an expression tag.
Example:
Actual event value = 82.687545776
Tags:
TestTag01 has the raw value and TestTag02 has the expression value
Expression:
round({[.]TestTag01.value}, 2)
Result:
Both alarms have the same trigger value, but TestTag02 displays with only two decimal places.
Here is how that looks in a derived tag:
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Very neat idea!
My tag was originally a reference tag (pointing to an MQTT Engine tag), so I changed it to a derived tag and applied the read expression exactly as shown, and now it works! 
I'm a little disappointed not to get any official response from IA as to whether the alarm object display should respect the source tag formatting for displaying data, but am happy I have a neat workaround.
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