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Using PI DataLink and Processbook

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  1. Using PI DataLink and Processbook The Visuals

  2. Introductions • Instructor • Students • Tell us about your PI System • What is your role with PI? • What skills do you need to learn?

  3. Course Overview • Length: 1 day • Interactive course: • Theory 50% • Exercises and examples 50%

  4. Objectives • Understand the fundamentals of PI technology • Learn to access data in the PI server • Become familiar with the use of PI Datalink and Processbook Please ask questions as they arise!

  5. Course Content • Introduction to PI • Common Dialog Windows • PI Tags • Data Flow • PI Time Format • PI Processbook • PI Datalink

  6. 1.0 Introduction to PI

  7. 1.0 PI Basics

  8. 1.1 What is a PI System?

  9. The PI System 2010 Windows integrated security PI System 2010 PI Server PI Notifications PI Analytics High availability PI Asset Framework PI Archives PE Totalizer PI ACE 64-bit product Real-time Interfaces Virtualization Real-Time DataDCS / PLC / SCADA / OPC HISTORIANS / INTERFACES Custom DataAPIs / SDKs IT DataIT MONITOR Relational Data OLEDB / ODBC SQL SERVER / ORACLE Web ServicesSOA / EXTERNAL DATALEGACY APPS

  10. Basic Parts

  11. Architecture of a Typical PI System

  12. 1.2 PI Tags

  13. What is a PI Tag? • It is a unique storage point for data in the PI system. It is simply a single point of measurement. • Examples • A flow rate from a flowmeter • A controller’s mode of operation • The batch number of a product • Text comments from an operator • The results of a totalizer or calculation

  14. PI Tag Attributes – Display • Tag name: unique name of the PI point • Descriptor: PI tag description • EngUnits: Engineering units • PointType: type of variable stored • Zero, Span and Typical value: minimum, range and typical values • Point source: allows grouping of PI tags by data interface (DCS,PLC, or other sources)

  15. Data Flow

  16. Data Tests Every value can go through 2 data screening tests before being archived: Exception Test“Send only significant changes in data to the server” Compression Test“Store only data needed to reliably represent process behavior”

  17. Data Flow Data acquisition node PI server

  18. New Event Processing Snapshot Event Queue PI Interface Data Compression file(s) ExceptionReport PISnapSS Shared Memory Archive PIArchSS Online Archives Archive Cache Primary Archive

  19. Exception Filtering

  20. New Event Processing Snapshot Event Queue PI Interface Data Compression file(s) ExceptionReport PISnapSS Shared Memory Archive PIArchSS Online Archives Archive Cache Primary Archive 1

  21. Exception Test (Interface Level) • Exception test: ExcMax (time) + ExcDev Current Snapshot - ExcDev • New values outside the box violate the exception test • The exception test is performed by the interface • When a value violates the exception test, this value and the previous one are sent to the PI server

  22. Exception Test When a value violates this test, that value and the previous value are reported. Why? To have a better representation of the actual tag behavior passes the exception test Trend if previous value is not sent Trend if previous value is sent Previous value Temperature +/- Excdev Snapshot value Time

  23. Raw Data - Example • Raw values scanned on the data source. • Without Exception and Compression tests, these would all be archived Temperature Time

  24. Exception Test - Example Temperature P E E E E E E E P E P E E P E Time E: Exception P: Previous

  25. Exception Test - Results Successive values sent to the PI Server. When a value is sent, it becomes the new snapshot. Temperature Time

  26. Turning Off Exception? • Behavior of ExcDev = 0, ExcMax = 0, is that Exception Test is turned off: • All values are sent to PI; • This will increase the traffic between the data collection node and the server.

  27. PI Exception Test - Example 12:02 51.1 12:02 51.1 12:00 50.0 12:00 50.0 12:12 51.4 Yes No Yes Yes No 12:00 50.0 12:01 50.3 12:02 51.1 … … 12:12 51.4 • Scan = 1m, ExcDev = 1, ExcMax = 10m DCS Value Exception Current Snapshot

  28. PI Server Snapshot and Data Compression

  29. New Event Processing Snapshot Event Queue PI Interface Data Compression file(s) ExceptionReport PISnapSS Shared Memory Archive PIArchSS Online Archives Archive Cache Primary Archive 2

  30. Snapshot • The snapshot contains the most recent value, for each tag in the PI server

  31. New Event Processing Snapshot Event Queue PI Interface Data Compression file(s) ExceptionReport PISnapSS Shared Memory Archive PIArchSS Online Archives Archive Cache Primary Archive 2

  32. Compression Test (PI Server) Current snapshot • Compression test: + Compdev Last archived value - Compdev < Compmax (s) • If a value between the last archive event and the current snapshot is outside the box, the current snapshot violates the compression test. In this case, the value previous to the current snapshot will be archived. • The compression test is done by the PI server • Compression can be turned off with the Compressing attribute

  33. Compression Test – Example The compression algorithm is performed on new snapshots to determine which data is kept in the PI archives A A Temperature A A A A A Time A: Archived Value

  34. Compression Results Values kept in the PI archives Temperature When the user requests a tag-time for which the value is interpolated, the difference can be no greater than ±compdev Time

  35. Compression Results After Exception. Raw values scanned. After Compression. Temperature Time

  36. New Event Processing Snapshot Event Queue PI Interface Data Compression file(s) ExceptionReport PISnapSS Shared Memory Archive PIArchSS Online Archives Archive Cache Primary Archive 3a 3b

  37. Turning Off Compression? • Behavior of Compression: • Compressing set to Off: all exceptions are archived(no compression); • Better Compressing set to On, CompDev set to 0: successive identical values (or values aligning perfectly) are not archived. This is much more efficient. • It is appropriate to turn off data compression for laboratory, manually entered, totalized, and other tags where each event is significant in itself

  38. Data Compression – How Much Data? This highly variable data can not be compressed by PI. Every value is a pivot point for the compression algorithm. All values are archived. This data appears highly compressible. Probably only three or four of these values would be stored in the archive.

  39. Data Flow • The exception and compression specifications should be adjusted to achieve efficient archive storage without losing significant data Disk space and Performance vs Data accuracy

  40. Exception and Compression Attributes • Each PI Tag can be individually configured for its exception reporting and compression

  41. Set Appropriate Zero & Span • Be careful when defining Zero and Span attributes because: • ExcDevPercent and CompDevPercent attributes are automatically adjusted according to Span; • The accuracy and range of Float16 values are set by the Zero and Span; • Zeroand Spanare used by many functions in PI ProcessBook.

  42. Step Attribute • The Step attribute affects both display and compression: • Instead of using the usual compression algorithm, a second exception test is applied using the CompDev value.

  43. Exception and Compression Defaults • ExcDevPercent = 1 (% of span) • ExcMax = 600 (10 minutes) • CompDevPercent = 2 (% of span) • CompMax = 28800 (8 hours) • Zero = 0 • Span = 100

  44. Recommendations • Set the compression deviation to the minimum change that is measurable by the instrument. • Set the exception deviation to ½ of the compression deviation. • These are starting point recommendations.

  45. 1.3 PI Time Format

  46. PI Time Format • Absolute (a specific point in time) • * : (NOW) • t : 00:00:00 on the current day (TODAY) • 18-feb-05 16:00:00 • Relative (time is offset from another time) • +8h : + 8 hours • Combined • t+8h : today + 8 hours

  47. Absolute Time dd-mmm-yy HH:mm:ss.00000 dd Day mmm Month (Jan, Feb, Mar, Apr, May, …) yy Year HH Hours in 24 hour format mm Minutes ss Seconds 00000 Milliseconds Example: 18-feb-05 10:43:29.323

  48. Absolute Time dd-mmm-yy HH:mm:ss • "Date" fields default to the current date • "Time" fields default to 00.

  49. Absolute Time – Other Formats Absolute time formats

  50. Relative Time • Number of: • Hours (h) • Minutes (m) • Seconds (s) • Leading sign (+ or -) is required. • No default time unit: must specify d, h, m, s, w, mo, or y • Can use fractions only for Hours, Minutes and Seconds • +2.5h, -0.5m • Relative time is most often part of a Combined time • Weeks (w) • Days (d) • Years (y) • Months (mo)