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Rank: Advanced Member
Groups: Member
Joined: 5/14/2009
Posts: 35
Location: UK
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Hi,
We are not currently using any Totalizer tags but it has been suggested we move some of our daily calcs to them.
As I'm sure you already know, time series PE functions like TagTot can be archive intensive when looking for the last day of data (288 * 5 minute readings), and when you have thousands of calc tags doing this they could make other scheduled scans/calcs skip.
I was advised to put Totalizers in for our PEs that use built in functions like TagTot, TagAvg, findeq, findXX, timeeq, timeXX2 etc., but I have reservations about the Totalizer system eg:
- max 5000 events
- values not stored (ie no recalculations etc)
PI Ace is not currently available, so I would prefer to use a cumulative total PE instead that runs every 5 minutes and resets at midnight:
IF yearday(Prevevent('sourcetag', '*-5m')) = yearday('y') THEN 'sourcetag' ELSE ('ThisTag' + 'sourcetag')
But what are other peoples views on the Totalizer? Does it cause more problems than it is worth ?
Thanks
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Rank: Member
Groups: Member
Joined: 1/14/2010
Posts: 28
Location: UK
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Hi ThePiMan,
We are in the same boat.
We now have that many tags, the tagtots are causing the 5 min calcs to be pushed back.
We were advised to use totalizers as well, but like you said, the idea of these being unable to recalculate is a big issue for us.
They are fine when everything is ok and running,but if there is a down period, they dont work.
to get round the problem of tag tots, i have basically added more scan rates around the midnight hour, with longer off sets and change the calc to be along the lines of:
TagTot('sourcetag', 'Y', 'T')
that way, by using the Y and the T, is doesn't matter when the calc runs, it picks up the time stamps from Yesterday @ midnight and Today @ midnight.
it seems to have helped quite a bit.
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Rank: Advanced Member
Groups: Member
Joined: 12/3/2009
Posts: 71
Location: Germany/Pennsylvania
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Hi,
We also did such calculations using PE tags executed by dedicated scan classes, exactly for the same reasons described above. In addition there is one subsystem less to run :-)
Depending on your compression settings the quality of the data is not better.
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Rank: Advanced Member
Groups: Member
Joined: 5/14/2009
Posts: 35
Location: UK
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Hey Pho, Check the date of my post. Your boat WAS my boat at that time. Your solution sounds very familiar, but I never had the time to implement it  Welcome to the boards .
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