10 Replies Latest reply on Jan 31, 2018 10:11 AM by janospetro

month?

Waly@osi Jan 25, 2018 7:27 AM

I have accumulated energy reading..usually i get the reading every hour then subtract the reading of the required hour and the reading of the previous hour..eventually if the data has no change i get 0 means no consumption..how i can apply this way in PI server or if there better way Plz advise but i should get a reading every hour even if no change 0 should be there

I have used range function to get the result in another created tag but its not accurate and if no change in data i'm not getting a result

Re: How to calculate power consumption every hour /day /month?

rzandvliet Jan 25, 2018 8:35 AM (in response to Waly@osi)

you can use a AF Analysis, that is running every hour.
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- Re: How to calculate power consumption every hour /day /month?
  
  Waly@osi Jan 25, 2018 1:59 PM (in response to rzandvliet)
  
  thnaks for your replay
  this will be valid if i want show data in FTVantagePoint reporting system?
  
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  - Re: How to calculate power consumption every hour /day /month?
    
    rzandvliet Jan 25, 2018 2:04 PM (in response to Waly@osi)
    
    You can store the result of your calculation at a PI Point. If you can send data to FT Vantage Point, then that should be possible.
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Re: How to calculate power consumption every hour /day /month?

sraposo Jan 25, 2018 4:17 PM (in response to Waly@osi)

Hi Ramadan,

As Robert Zandvliet mentioned you can use a periodic analysis running every hour for the hour power consumption. If my understanding or your question is correct you could use:

TagVal('Attribute') - PrevVal('Attribute','*')

For the daily calculation, you could schedule your analysis to run periodic at midnight and use

TagVal('Attribute') - TagVal('Attribute','y'). Please note that TagVal interpolates if there's no archive value.

For the monthly calculation, you can run it daily at midnight and use an If statement to check if we are on the first of the month:

IF Day('*') = 1 THEN TagVal('Attribute') - TagVal('Attribute','*-1mo') else NoOutput()

Hope this helps,
Seb
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- Re: How to calculate power consumption every hour /day /month?
  
  Waly@osi Jan 27, 2018 2:03 PM (in response to sraposo)
  
  thanks Sebastien Raposo
  actually im trying to use performance equation as per attached screen shots but i don'nt know why im getting this result , i suppose o get 4 but im getting 0.6xx
  
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  - Re: How to calculate power consumption every hour /day /month?
    
    janospetro Jan 29, 2018 12:19 PM (in response to Waly@osi)
    
    Hi Waly Ramadan,
    
    The result is correct because TagVal('tag','*-1h') uses an interpolated value at your calculation.
    Try PrevVal('tag','*-1h') instead!
    
    Regards,
    Janos
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    - Re: How to calculate power consumption every hour /day /month?
      
      Waly@osi Jan 31, 2018 7:41 AM (in response to janospetro)
      
      thanks Janos
      but what does it mean "interpolated value"
      
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      - Re: How to calculate power consumption every hour /day /month?
        
        janospetro Jan 31, 2018 10:11 AM (in response to Waly@osi)
        
        Hello Waly,
        
        PI Data Archive mainly deals with Real-Time data series. To make an 'archive' of the data sequence of a 'realtime'-measurement, PI uses a complex techique for compression, normally. (Introduction to Exception & Compression for PI Points )
        
        At the end we need an original-like value for a given moment in the past, but we only have compressed values. (In most cases with no archived value at all for that specific moment!)
        PI uses the mathematical method linear interpolation: retrieved values are computed from the compressed data by interpolation.
        (Linear interpolation - Wikipedia ) With correct settings the interpolated data should ideally match the real-time uncompressed data.
        
        One can disgard this default retrieval mode for a tag by setting it's 'Step' attribute to 1. Please check discussion: https://pisquare.osisoft.com/message/100823-re-analysis-substituted-is-tagval-interpolated#comment-100823 .
        
        The whole topic has a picturesque explanation through using PI Datalink and it's data retrieval modes:
        PI Data Interpolation and Retrieval Modes in PI DataLink
        
        Janos
        
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  - Re: How to calculate power consumption every hour /day /month?
    
    sraposo Jan 29, 2018 2:13 PM (in response to Waly@osi)
    
    Hi Waly,
    
    You may want to consider moving this calculation to Asset Analytics if possible. Asset Analytics have more functionality than performance equations and are leveraged in PI AF. They can be templatized and it's much easier to backfill or recalculate Asset Analytics.
    
    Regards,
    Seb
    
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    - Re: How to calculate power consumption every hour /day /month?
      
      Waly@osi Jan 31, 2018 7:43 AM (in response to sraposo)
      
      Hi Sebastien
      i never used PI AF , is there any resource where i can start fast
      
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