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inconsistent calculated measurement values in openPDC and Historian

Feb 8, 2013 at 7:42 PM
I defined four measurements as "warning signal","frequency delta", "excursion type" and "estimated size" for Frequency Excursion Action Adapter. I use FDR real-time frequency data as output and managed to observe values for those four measurements in "Calculated" of "Monitoring->Device Measurements". I setup alarms to monitor those values as well.

However, there is inconsistency issue between the calculated measurement values in openPDC and Historian. In openPDC, the alarm status page shows the frequency delta value at 02/07/2013 22:19:47 is 0.0134333. However, when I export Historian data, the frequency delta value at exactly the same time is 0.0058 in the CSV file. And there isn't any delta value as 0.0134333 around that time. I don't know why this happens and which one is the correct one.

Also, I put the historian storing these four values under the same folders as PPA historian(C:\Program Files\openPDC\Archive). But when I open "HistorianPlayBackUtility.exe" to browse this folder, I can only see/export these four values, but I cannot see any measurement tags in PPA(device measurements). I don't know why.

I would really appreciate if anyone can tell me how I can solve these problems. Thank you very much!