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C# SDK - How to find the number of times a tag is under a certain value

Question asked by jscotti on Jan 14, 2015
Latest reply on Mar 2, 2015 by viveks

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I need some help,

I am trying to find the amount of times a tag is under a certain value for the past 30 days.

I've posted my code below,

It doesn't seem to be working because no matter what I change the expression to it always shows either 1 or 0

            _pisdk = new PISDK.PISDK();
            PISDK.Server piServer = _pisdk.Servers["SERVER"];
            PISDK.Server myServer;
            PISDK.PIPoints myPoints;
            PISDK.PIPoint myPoint;
            PISDK.PIData myPIdata;
            PISDK.IPIData2 ipidata2;
            PISDKCommon.NamedValues nvsSum;
            PISDK.PIValues pvs;
            myPoints = piServer.PIPoints;
            myPoint = myPoints["TAG"];
            myPIdata = myPoint.Data;
            ipidata2 = myPIdata as PISDK.IPIData2;
            string expression = "'TAG' < 40";
            nvsSum = ipidata2.FilteredSummaries("*-30d", "*", "", expression, PISDK.ArchiveSummariesTypeConstants.asTotal, PISDK.CalculationBasisConstants.cbTimeWeighted, PISDK.FilterSampleTypeConstants.fstExpRecordedValues);
            int p = nvsSum.Count;

Eugene Lee

Jan 15, 2015 3:26 AM

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Hi jscotti, if you want the number of times, you shouldn't use the asTotal. Instead, you should use asCount. I have tested the code below on my machine and it works well. I have also removed the declaration of MyServer since you didn't use it anywhere else.

            PISDK.PISDK _pisdk = new PISDK.PISDK();
            PISDK.Server piServer = _pisdk.Servers.DefaultServer;
            PISDK.PIPoints myPoints;
            PISDK.PIPoint myPoint;
            PISDK.PIData myPIdata;
            PISDK.IPIData2 ipidata2;
            PISDKCommon.NamedValues nvsSum;
            PISDK.PIValues pvs;
            myPoints = piServer.PIPoints;
            myPoint = myPoints["cdt158"];
            myPIdata = myPoint.Data;
            ipidata2 = myPIdata as PISDK.IPIData2;
            string expression = "'cdt158' < 400";
            nvsSum = ipidata2.FilteredSummaries("*-30m", "*", null, expression, PISDK.ArchiveSummariesTypeConstants.asCount, PISDK.CalculationBasisConstants.cbEventWeighted, PISDK.FilterSampleTypeConstants.fstExpRecordedValues);
            pvs = nvsSum["Count"].Value;
            double n = pvs[1].Value;

This returns me a result of 1801 because all of my cdt158 events are under 400.

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21 Replies

Dan Fishman Jan 14, 2015 9:35 PM
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Maybe try nvsSum["total"].value[1].value

That will give you back the value (might want make it a double). Just nvsSum["total"].value[1] will return a PIValue.

Regards,
Dan
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dng

Jan 14, 2015 10:01 PM

You can also use the PIData.RecordedValues method to find the number of time a tag is under a certain value (during a time period).

e.g.

PIValues sum = myPIdata.RecordedValues("*-30d", "*", BoundaryTypeConstants.btInside, expression, FilteredViewConstants.fvRemoveFiltered);
int p = sum.Count;

I have moved this post to the PI Developers Club > General Programming Languages subspace because community members there can best address your programming questions!

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ashaw

@ dng on Jan 14, 2015 10:20 PM

Another way:

            PISDK.PISDK myPISDK;
            myPISDK = new PISDK.PISDK();
            PISDK.Server srv;
            PISDK.PIPoint pt;
            PISDK.PIValues values;
            int count = 0;


            srv = myPISDK.Servers.DefaultServer;
            pt = srv.PIPoints["sinusoid"];
            values = pt.Data.RecordedValues("1-jan-15", "10-jan-15");

            foreach (PISDK.PIValue value in values)
             {
                Console.WriteLine(value.Value + " " + value.TimeStamp.LocalDate);
                if (value.Value is Single && value.Value > 50)
                {
                    count++;
                }
             }
            Console.WriteLine("Sinusoid was above 50 " + count + " times from 1-jan through 10-jan");
            Console.ReadLine();

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bperry @ ashaw on Jan 14, 2015 10:37 PM
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This does work, but whenever possible, it's best to get the PI Archive to filter the values server-side (as Daphne Ng recommended). This way the entire collection of values isn't pushed to the client.
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Dan Fishman Jan 14, 2015 10:04 PM
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Do you want to find the number of times the values is under 40 or the amount of time?

Dan
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Eugene Lee

Jan 15, 2015 3:26 AM

            PISDK.PISDK _pisdk = new PISDK.PISDK();
            PISDK.Server piServer = _pisdk.Servers.DefaultServer;
            PISDK.PIPoints myPoints;
            PISDK.PIPoint myPoint;
            PISDK.PIData myPIdata;
            PISDK.IPIData2 ipidata2;
            PISDKCommon.NamedValues nvsSum;
            PISDK.PIValues pvs;
            myPoints = piServer.PIPoints;
            myPoint = myPoints["cdt158"];
            myPIdata = myPoint.Data;
            ipidata2 = myPIdata as PISDK.IPIData2;
            string expression = "'cdt158' < 400";
            nvsSum = ipidata2.FilteredSummaries("*-30m", "*", null, expression, PISDK.ArchiveSummariesTypeConstants.asCount, PISDK.CalculationBasisConstants.cbEventWeighted, PISDK.FilterSampleTypeConstants.fstExpRecordedValues);
            pvs = nvsSum["Count"].Value;
            double n = pvs[1].Value;

This returns me a result of 1801 because all of my cdt158 events are under 400.

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Rick Davin

@ Eugene Lee on Jan 15, 2015 2:45 PM

At risk of stating the obvious (or as least to most but not all readers), this correct answer works not just because of asCount but also because you use cbEventWeighted instead of cbTimeWeighted. Both options used in tandem provide the proper answer.

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Eugene Lee

@ Rick Davin on Jan 16, 2015 1:51 AM

Yes, and also in addition to that, here are some more calculation basis types from the PI SDK reference manual that you can use.

cbTimeWeighted	Weight the values in the calculation by the time over which they apply. Interpolation is based on the step attribute of the point. Interpolated events are generated at the boundaries if necessary.
cbEventWeighted	Evaluate values with equal weighting for each event. No interpolation is done. There must be at least one event within the time range to perform a successful calculation. Two events are required for standard deviation. In handling events at the boundary of the calculation, PISDK uses following OPC standard: 1) use events at both boundaries when there is only one calculation interval; 2) include events at start time in multiple intervals and the intervals are in ascending time order; 3) include events at the end time in multiple intervals and the intervals are in descending time order.
cbTimeWeightedContinuous	Apply weighting as in cbTimeWeighted, but do all interpolation between values as if they represent continuous data, (standard interpolation) regardless of the step attribute of the point.
cbTimeWeightedDiscrete	Apply weighting as in cbTimeWeighted but interpolation between values is performed as if they represent discrete, unrelated values (stair step plot) regardless of the step attribute of the point.
cbEventWeightedExcludeMostRecentEvent	The calculation behaves the same as cbEventWeighted, except in the handling of events at the boundary of summary intervals in a multiple intervals calculation. Use this option to prevent events at the intervals boundary from being double count at both intervals. With this option, events at the end time(most recent time) of an interval is not used in that interval.
cbEventWeightedExcludeEarliestEvent	Similar to the option cbEventWeightedExcludeMostRecentEvent. With this option, events at the start time(earliest time) of an interval is not used in that interval.
cbEventWeightedIncludeBothEnds	With this option, events at both ends of the interval boundaries are included in the event weighted calculation.

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pthivierge

Jan 15, 2015 10:15 AM

Hello Mr. Scotti,

Is there a reason why your are not using the AF SDK? PI AF SDK is our latest technology, can connect to both PI Data Archive and AF. It is regularly updated, benefits from newest technologies and is the recommended SDK to use for new projects.

Having this said, in case you would like to achieve the same thing using the AF SDK, I am providing you an example. The example gives the number of occurrences (Count) where cdt158 exceeded 170.

Add a reference to OSIsoft.AFSDK

using OSIsoft.AF;
using OSIsoft.AF.PI;
using OSIsoft.AF.Data;
using OSIsoft.AF.Time;

public static void FilteredSummariesExample()
        {
            var piserver = PIServer.FindPIServer("Optimus");
            piserver.Connect();

            var point = PIPoint.FindPIPoint(piserver,"cdt158");
           
            var timeRange = new AFTimeRange("*-2h", "*");
            var res = point.FilteredSummaries(timeRange,
                                    new AFTimeSpan(timeRange.Span),          // calculation window, since we want a single result, we make it equal to our time range
                                    "'cdt158'>170",                          // true/false expression evaluated for one minute window
                                    AFSummaryTypes.Count,                    // summary to return
                                    AFCalculationBasis.EventWeighted,        // base
                                    AFSampleType.ExpressionRecordedValues,   // sampling, interpolated or recorded values
                                    AFTimeSpan.Zero,                         // Sampling interval, N/A in this case
                                    AFTimestampCalculation.Auto              //
                                    );


            Console.WriteLine(string.Format("Number of results:{0}", res[AFSummaryTypes.Count].Count));
            Console.WriteLine(string.Format("Number of times 'cdt158'>170 :{0}", res[AFSummaryTypes.Count].First().Value));


        }

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viveks @ pthivierge on Feb 27, 2015 2:32 AM
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Hi Patrice,
I tried using this sample code but I don't not get the PIPoint or PIServer classes getting resolved. Any ideas? I am using VS2013 and PI AF version is 2.5. I have added the references to the above assemblies too.

Thanks
Vivek
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- Eugene Lee @ viveks on Feb 27, 2015 2:48 AM
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  Hi Vivek,
  
  Remember to target at least .NET4.0 for your application because these classes only reside in .NET4.0 version.
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  - viveks @ Eugene Lee on Mar 2, 2015 3:16 PM
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    Thanks Eugene. I was infact targeting 4.0, but hadn't added the assemblies from the 4.0 folder. Now it works.
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jscotti Jan 15, 2015 2:38 PM
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Thank you all for the quick responses, Eugenes answer is working for me
it was the pvs[1].Value that I needed

Patrice , I plan to eventually modify all the legacy code into the AFSDK, just haven't had the time yet
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jscotti Feb 19, 2015 12:31 AM
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Hey guys could you help me out one more time, how would I also get the timestamp from every time this event occured?

Thanks
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- Dan Fishman @ jscotti on Feb 19, 2015 12:54 AM
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  If using the PI SDK try using the RecordedValues method. See the PI SDK RecordedValues method for more information.
  
  RecordedValues StartTime, EndTime, BoundaryType, [FilterExp], [ShowFiltered], [AsyncStatus]
  
  This method returns a PIValues collection. There are many similar posts on the PISquare and here is one of the first I found. There are a number of samples using the AF SDK. Let us know and we can provide a link to AF SDK code or work with you do get what works best. Note, the filtering occurs on the PI Server.
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  - dng @ Dan Fishman on Feb 19, 2015 1:27 PM
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    Yep! I gave an example with recorded value on the second comment above.
    
    PIValues vals = myPIdata.RecordedValues("*-1d", "*", BoundaryTypeConstants.btInside, expression, FilteredViewConstants.fvRemoveFiltered); foreach (PIValue val in sum) { Console.WriteLine(val.TimeStamp.LocalDate); }
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    - Dan Fishman @ dng on Feb 19, 2015 1:37 PM
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      Ha! Nice! I should have just linked back to this thread. How about a discussion on how to avoid duplicate data within the PI System .
      
      Dan
      
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    - jscotti @ dng on Feb 19, 2015 5:52 PM
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      thanks but this is not working, I'm passing the same expression from my filtered summaries but im getting an empty pivalues collection.
      I know it has happened at least once, the filtered summary asCount returns 6 times
      I cant get the timestamps from the FilteredSummaries function?
      
      _pisdk = new PISDK.PISDK(); PISDK.Server piServer = _pisdk.Servers["server"]; PISDK.PIPoint myPoint; PISDK.PIData myPIdata; PISDK.PIValues pvs; string results =""; string tag = "myTag"; string setpoint = "40"; string expression = "('" + tag + "'< " + setpoint + " AND prevval('" + tag + "',curtime) > " + setpoint + ")"; myPoint = piServer.PIPoints[tag]; myPIdata = myPoint.Data; pvs = myPIdata.RecordedValues("*-30d", "*", BoundaryTypeConstants.btInside, expression, FilteredViewConstants.fvRemoveFiltered); foreach (PIValue val in pvs) { results += val.TimeStamp.LocalDate.ToString() + ","; }
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      - Dan Fishman @ jscotti on Feb 19, 2015 6:36 PM
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        What is curtime? What if you replace curtime with *.
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      - dng @ jscotti on Feb 19, 2015 7:01 PM
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        You cannot get timestamps from the FilteredSummaries function because the method only returns summary results of the calculation (after applying the filter), instead of returning each individual event. I could not reproduce your results, and both FilteredSummaries and RecordedValues gave me the same results (in terms of count). My best advice is to put the two functions side-by-side in your code to make a comparison and make sure your filter expression is indeed satisfied by some events. You can also use some default tags for testing.
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        Dan Fishman @ dng on Feb 19, 2015 7:05 PM
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        Yeah, definitely need to do both. Summaries is for summary values and not for raw PI Point Values.
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C# SDK - How to find the number of times a tag is under a certain value

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