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I'm checking for one PI tag in Datalink & in Processbook. In Datalink I see Compressed Data interrupted few hours ago, in Processbook for the same PI tag I see continuous trend, which looks normal.

I thought the both tools should show the results for the same tags.

Why are they giving different results?

codea
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duck
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  • Why is this question tagged 'pi', which is for π, the ratio of a circle's circumference to its diameter, i.e. 3.14159265...? And by the way: https://pisquare.osisoft.com/thread/15223-pi-processbook-pi-datalink – Pang Nov 12 '16 at 10:19

2 Answers2

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There can be many rasons. What comes to my mind here is that there is an automatic update mecanism in PI ProcessBook, with PI DataLink you need to manually refresh the content.

So for example if the data collection had an issue (e.g. network outage) for many hours and the data was buffered on an interface or a connector node, when the data will flow in the system after network is back then PI Processbook will show changes right away, this is not the case for PI DataLink, it will require a manual refresh of the data in Excel with the PI Datalink Add In.

codea
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    ProcessBook also updates the display directly from the snapshot (real-time incoming data), whereas DataLink is only showing data that has been written to the archive (for long term storage). – i did not pay the royalties Oct 06 '17 at 12:54
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    Note on PI Processbook: For any new development you should consider using PI Vision. – codea Nov 05 '20 at 14:10
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In short, PI ProcessBook caches data from PI snapshot, while DataLink does not.

PI ProcessBook trends update data from snapshot in real time and cache them at the client, so when the archive is somehow interrupted, the client won't be affected unless you hit refresh, which clears the client side cache and pulls data all over again from server archive(for history) & snapshot(for current value).

PI DataLink retrieves data from archive each time you calculate the spreadsheet. It does not cache snapshot values over time to create a history data record or trend. That's the main reason you are seeing this difference between PB and DL.

You could also contact OSIsoft (now part of AVEVA) techsupport for help.

Zhengqi Ge
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