Data Entry Tags showing NoData for most recent Values
Hello,
I'm having a problem where my tags that contain values from a data entry box show NoData when trying to display the most recent value in a Value Box. This problem also happens in graphs it just stops the graph at the time the most recent value was entered.
8 replies
-
Hi ,
A value box will display the most recent update that is stored in the Historian. Is it possible that the values being stored using the Data Entry control are using timestamps that fall before the last value in the Historian? Are you able to look at the data through the Views tiles within the Canary Admin tool?
Another way to look at the raw values in Axiom is to use a Data Table. By default, it displays raw data. You could also try the Excel Add-in and use the Raw Data function. Anything to see what the raw values look like. This might help us determine what's going on. -
, I am using a Value Box timestamp that's after the input time of the data entry, I can see the values in a Data Table. Is there any way to display the data in a Value Box?
-
Hi
The only way I know this can happen is if the last value in the Historian has a NoData quality. You would need to look at the tag in the Historian using the Canary Admin to confirm this.
-
sorry I understood that looking at the data table would do the same, here is a screen shot of the data from the view tile in the administrator. When I use a value box that has no AggregateKind or AggregateInterval and a aggregate timestamp of 4/2/2025 1:00:00 PM it gives me NoData.
-
Thanks for the screenshot . I think I see what's going on. Based on your comment of using an "aggregate timestamp of 4/2/2025 1:00:00 PM" and your screenshot, there is no data at or beyond that point in time in the Historian. The last value in the Historian is 3.5 hours before the aggregate start time the ValueBox is set to. That would explain why it displays a NoData.
Is there a reason you need an AggregateStartTime?
This would also explain why the trend stops at this point in time. Axiom does not extend the last value in the Historian if the tag is not being actively written to. We have no way of verifying that the value is good up until Now. Whereas, if we are actively logging a tag that just hasn't changed in a while, we virtually time-extend the last value because we are connected to the source from which we are polling.
-
That makes sense that it doesn't extend the last value, is there any way to get it to? I'm having to use a aggregate start time because I'm using a script from a date picker to be able to look at different day's values and the operator enters the data in a one hour window so I just picked a time that would be well after that.
-
The only way I've done this, and it's not a great solution, is to create a calc tag which essentially is a duplicate of the data entry tag. The only difference is, the calc is always running so it has an active writer which extends the last value.
-
10-4 I'll give that a try, thank you for all the help!
-
Print this page