6 Replies Latest reply on Jul 18, 2011 5:07 PM by rzandvliet

    AFAttribute GetValues

    mrai
    mrai Dec 1, 2009 12:18 AM

      Hi,

       

      The GetValues() method returns all the data for an attribute for the time range. Is there any method that returns values for the attribute but in specified intervals?

       

      Example:

       

      An AF Attribute references a PI Point that is collecting data every 2 seconds. When we call GetValues() for this attribute for a time range, it gives all the data collected. Is there a function that can return values for the same attribute but for 1 hour interval for the given date range.

       

      Thanks

        • Re: AFAttribute GetValues
          hanyong
          hanyong Employee Dec 1, 2009 6:33 AM (in response to mrai)

          Hi,

           

          You can try the following:

          AFAttribute a = c.Attributes["point1"];

          AFTime st = new AFTime(DateTime.Today);
          AFTime et = new AFTime(DateTime.Today.AddHours(2));

          AFTimeRange tr = new AFTimeRange(st, et);

          AFValues vals = a.GetValues(tr, -3, a.DefaultUOM);

          foreach (AFValue val in vals)
          {
              Console.WriteLine(val.Timestamp.LocalTime.ToString() + val.Value.ToString());
          }

          The important thing to note is that we are using the overload of "AFAttribute.GetValues(AFTimeRange timerange, int numberofvalues, UOM)" here. A negative number would get you a fixed number of interpolated results, supported by PI Point DR.

           

          So in my example, start time is 12 am today, end time is 2 am, setting -3 will give me the result of 3 interpolated values:

           

          12/1/2009 12:00:00 AM 168.1097
          12/1/2009 1:00:00 AM 167.5027
          12/1/2009 2:00:00 AM 161.7574

           

          You would probably need to add on additional method to translate a fixed interval to a number of intervals before passing to AFAttributes.GetValues(). =)