AnsweredAssumed Answered

Datalink expression is returning over range

Question asked by jeffshaw on Dec 5, 2016
Latest reply on Dec 7, 2016 by gregor

Hello, thank you in advance for reading this question.

 

I should mention I am using Datalink 5.0, and I have four pi tags configured in point builder as:

  • General:
    • FTLD point source
    • Point class: classic
    • Int16
  • Archive:
    • Scan: ON
    • Archiving: ON
    • Step: ON
    • Shutdown: ON
    • Compressing: ON
    • Exception Deviation: 1.5 Eng Units
    • Compression Deviation: 3 eng units.
  • Location1: 8 (which copy of the interface the point belongs to)
  • Location2: 0 (not used)
  • Location3: 1 (advise on change)
  • Location4: 1 (scan class)
  • Location5: 0 (no asynchronous read)

 

When I use datalink to poll 5 minute averages for these tags, I see them return values:

  • tag1a: ~233-250
  • tag1v: ~580-600
  • tag2a: ~3-5
  • tag2v: ~580-600

 

When I use the expression 'tag1a'*tag1v' I get the results I expect.

When I pass in an expression asking for 'tag2a'*'tag2v' the result is "Over Range".

 

I have attempted to change the span of the points to 600 which has not helped solve the problem.  I am surprised because the points individually return data and I am only asking PI to multiply the two together.  The results of the calculation are all less than the maximum storable int16 (2147486647) which I assumed could be the problem.

 

  1. Is the expression evaluation on the pi server using the span to report Over Range?
  2. Is datalink using the span to evaluate the result coming back from the expression as Over Range?
  3. Any idea how I can fix this?

 

I've attached a screenshot of the result set.   Thank you again for reading.  Please forgive me if I have categorized this question incorrectly.

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