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Historical trend of discrete device PVs overlay each other.

I have configured two historical trend windows for the same modules/parameters with quite different results for each. The first trend is a PHV view window of a loop point (PV, SP & OUT) and three valve PVs. In the PHV trend the PVs of the discrete valves are displayed as distinct visible layers. In the other trend window configured with the OLE Embedded Trend Ctrl the same module/parameters were configured with distinctly different results. The PVs of the discrete valves are shown trending on top of one another where finding the true value of a particular PV is impossible. Why are these different?

         

putelism

• 14 Dec 2017 1:13 PM
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3 Replies

• PRASHANT-MUTTEPAWAR

  

  • 14 Dec 2017 3:30 PM

  Hi
  
  historical trend windows for the same modules/parameters with quite different results for each : As seen from the graph screen shot the main discription are different so the parameters that were configured are not with the same modules/parameters .also both the graph shown the different description parameter References .
  
  Another thing is that for the discrete values parameter references are configured are different one shown as 31-xv-1701/pv_d and for another graph 31-xv-1701/pv_d.cv that may be the reason both graph shown different results.
  
  Regards
  
  Prashant

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• putelism

  

  • 15 Dec 2017 2:23 PM

  In reply to PRASHANT-MUTTEPAWAR:

  Prashant,

  Each parameter trend description can be modified to add clarity and help identify  which pen is which parameter (SP, PV or OUT). That does not make the point/parameter different.  

  Look at the attached jpg. I created the OLE tend (left side) using the Embedded Trend Ctrl with the six pens shown. Notice the 3 discrete device pv overlay each other. Using the right mouse function "Launch Process History View" automatically builds a PHV screen (right side) with the same pens, parameters, colors, descriptors etc. The PHV view looks correct because each discrete is given its own dedicated trend area on the chart.

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• KeithStThomas

  

  • 17 Jul 2023 11:55 PM

  In reply to putelism:

  I'm having a similar issue, but with PHV instead of the embedded trend. I have a trend of 4 discrete values with 4 individual pens that I saved. When I open the saved trend, all the pens are collapsed on top of each other onto a single line.
  
  If I Restore Chart, then all 4 pens will have 4 individual colours again.
  
  Is there a way to have the 4 pens show up as when the trend is opened? It is a pain to have to tell the operator that the kludge fix is to Restore Chart every time they look at the trend.

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