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Rank: Advanced Member
Groups: Member
Joined: 5/28/2009
Posts: 75
Location: Cheshire, UK
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Does anyone have experience or can point me to the right document to help me understand Tags (including Performance Equations) of type = String? My attempts to find info include: - Google Search. - OSI Site Search (1200+ articles!). - Searching this site. - PI Documentation. I have set up a string PE tag on our test system using the following equation: Code:If 'sinusoid'>30 then concat('sinusoid'," >30") else concat('sinusoid'," <=30") (taken from OSI training exercises) but this gives some strange and random results when displayed with ProcessBook. MilesUK
ProcessBook v3.0.15.3
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OSIsoft vCampus is a subscription-based, online offering that consists of providing everything people need to develop applications on the PI System. We invite you to take a "tour" of the OSIsoft Virtual Campus - also feel free to consult the FAQ or contact OSIsoft vCampus for more details.
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Rank: Advanced Member
Groups: Member
Joined: 4/7/2011
Posts: 137
Location: KZN, South Africa
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It works fine on my side, though I have PBook 3.2.0.0, also try and edit your comdev and compdevpct, the same goes for exception, below you will see my tag config, hope it helps
Tag STRING_TEST
archiving 1
changedate 02-Jul-08 08:55:19
changer piadmin
compdev 0
compdevpercent 0
compmax 28800
compmin 0
compressing 1
convers 1
creationdate 06-Jun-08 11:38:41
creator piadmin
datasecurity piadmin: A(r,w) | piadmins: A(r) | PIWorld: A(r,w)
descriptor N/A
digitalset
displaydigits -5
engunits
excdev 0
excdevpercent 0
excmax 600
excmin 0
exdesc If 'sinusoid'>30 then concat('sinusoid'," >30") else concat('sinusoid'," <=30")
filtercode 0
instrumenttag
location1 1
location2 0
location3 0
location4 2
location5 0
pointid 37936
pointsource C
pointtype String
ptclassname classic
ptsecurity piadmin: A(r,w) | piadmins: A(r) | PIWorld: A(r)
recno 27968
scan 1
shutdown 1
sourcetag
span 1000
squareroot 0
srcptid 0
step 1
totalcode 0
typicalvalue 1
userint1 0
userint2 0
userreal1 0
userreal2 0
zero 0
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Rank: Advanced Member
Groups: Member
Joined: 5/28/2009
Posts: 75
Location: Cheshire, UK
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Thank you, squatty. I'll work through your settings. In PB I am seeing a stair case plot. But not a straight line but curving, resetting part way back to zero or oscillating. Not saying it's wrong - just trying to understand what goes on. :-) MilesUK
ProcessBook v3.0.15.3
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Rank: Advanced Member
Groups: Member
Joined: 4/7/2011
Posts: 137
Location: KZN, South Africa
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You have to understand that PB does not really know how to trend a string value, in older versions of pbook string tags could not be trended at all. I think string tags are handled in the same manner as digital tags, instead of assinging a value with a string, pbook automatically does some sort of mapping to the string values in the current trend...but I've been proven wrong before
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Rank: Newbie
Groups: Member
Joined: 1/9/2012
Posts: 1
Location: Philadelphia, PA
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Since string tags do not have an inherent numerical value, ProcessBook assigns an integer value to each different string it encounters.
The first string it encounters gets 0, the next gets 1, etc. Every time a display is opened that contains a trend with a string tag the string tag can be plotted differently; depending on the values returned for the string tag when the display is opened - again the first string encountered during the plot time would be assigned 0, the next would get 1, etc.
Different string tags are assigned numbers in the same way. A different string tag, even with the same string values, could get different number values if that string did not arrive in the same order when it was trended.
Digital sets, although they appear as strings, actually have a number assigned to each member of the digital set. For a digital set, ProcessBook trends are plotted based upon the underlying number in the digital set.
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Rank: Administration
Groups: Administration
Joined: 6/20/2008
Posts: 617
Location: Cheshire, United Kingdom.
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Thanks for the explanation, Daniel. Principal Consultant
Real-Time Data Management @ Wipro Technologies
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Rank: Advanced Member
Groups: Member
Joined: 5/28/2009
Posts: 75
Location: Cheshire, UK
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I have had two docs suggested to me for anyone that is interested in string tags. Our supplier sugested "PI Server Management Guide" & OSISoft put forward "Introduction to PI Server System Management". I have yet to read either however OSISoft suggest that for string type tags the "exception maximum and minimum times, and the compression maximum and minimum" the main attributes. Thank you to all. MilesUK
ProcessBook v3.0.15.3
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