1 DevNet Unplugged 2002 “Express Your Innovations” Build a Strong Foundation PI Server Applications Martin Jetté, [email protected] OSI Developers Network

DevNet Unplugged 2002 “Express Your Innovations” 1

Build a Strong Foundation

PI Server Applications

Martin Jetté, [email protected]

OSI Developers Network

Copyright © 2002 OSI Software, Inc. All rights reserved.


PI UDS Server Side Calculation Applications

• PI Performance Equations

• PI Totalizer

• PI Alarm

• PI Real Time SQC

• PI Batch


Why use server Apps for Calculations

• Keeps a history of calculations and alarms• Calculation are centrally maintained• Everybody can make decisions based on the same

metrics• Calculated data is available to all PI client tools and

other systems (example: maintenance system)• Possibility to do Event based calculations rather than

Time based (Computations based on grade and products)

• Reduce calculation and network load => Calculate once and archive rather than recalculate every time a user opens a spreadsheet or dataset


PI Totalizer Subsystem• PI includes a powerful and flexible post-processor

engine that you can use to create totalizations and other simple calculations.

• The PI Totalizer subsystem calculates the following types of summaries: total, average, minimum, maximum, range, standard deviation and median.

• PI Totalizer can also calculate time that a condition is true and it can counts events.

• Many options are available for sampling, filtering and reporting (sending data) to PI.

• The PI Totalizer subsystem aggregates data from the PI Snapshot table rather than the archives (like PI PE). This can results in more precise calculations.


PI Totalizer vs PI Performance Equations

R egions tha t a re includedand excluded fo r a tim e-we igh ted ca lcu la tion usingP I T ota lizer

E vents tha t fa il com pression test

E vents tha t pass com pression test

R egion considered inT im e-W eigh ted ca lcu la tionusing C om pressed V a lues


PI Compression Test

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

-1 0 1 2 3 4 5 6 7 8 9 10 11Time

Parameters: Parameters: CompDev = 0.06CompDev = 0.06 OO

CC, ,

CompMax = 28800 sec, Compmin = 60 CompMax = 28800 sec, Compmin = 60 secsec

0.120.12


Compression(Result)

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

-1 0 1 2 3 4 5 6 7 8 9 10 11

Time Back


Configuration properties of a PI Totalizer Tag

Function/CalcMode- Determ inesthe type ofca lcu lation thatis done for theaccum ulation

TotalCloseM ode- Schedules the tim e for thereset of the accum ulation andwhen the value is set to P ISnapshot

ReportMode- Determ inesthe m anner inwhich the resultis sent to P ISnapshot

TotalizerTag

SourceTag

Filter Expression- F ilters out the valuessent to the accum ulation

RateSampleMode- Determ inesthe type ofsam pling


ReportModeRunning

Identical to Ramping except the timestamp of the totalized tag stays at second after the start of the totalization period. (Stair Case)

RampingBehaves like an accumulator that increases its value every time a new Snapshot value is read from the SourceTag. (Saw Tooth)

PeriodEndNo output reported until the end of the period

RunEstimateThe value is an estimate of the result if the rate point were to hold steady at its current value.

RunEst2The value is an estimate of the result if the rate point were to hold steady at the current average since the beginning of the accumulation interval.


Totalizer – Running and Ramping

CurrentPeriod

Period -1Period -2

Snapshot Values

Archived Values

CurrentPeriod

Period = 5m


Totalizer – RunEstimate and RunEst2

Period -1

CurrentPeriod

Period -2

Period -1

CurrentPeriod

Period -2

Period = 5m

Period = 5m

RunEstimate => Estimated result at Period End if the value is maintainedRunEst2 => Estimated result of Totalization at Period End if the current average is maintained

Period -1Period -2

Period -1 Current PeriodPeriod -2

Period = 5m

Period = 5m

Current Period

Estimate in time

Estimate in time

33


Totalizer - PeriodEnd

Period -1Period -2 CurrentPeriod

Keeps the sameValue until the End of the period

Period = 5m


Time and Event CountingEventEQ and EventNE make comparisons to the value of the CompValue field.

Use CalcMode of TimeTrue to count the number of seconds the SourceTag has the value specified in the Function field (i.e., EventEQ, EventNE etc.).


PI Performance Equations

• Allows for the configuration of server based calculations– Access to all PI tags

– Access to Snapshot and archived data

– Advanced math and archive functions

– Access PI Steam tables

– Calculation can be event based and scan based

15

Calculation expressions• Mathematical Operators:

+ - * / ('sinusoid')/2 + ('flow.pv'-100)

• Functions:abs(), atn() BoD(), BoM()

cos(), sin(), tan() exp(), e (2.71828...), log()

int(), sgn(), sqr()concat(), mid(), Ltrim()

• Relational Operators<, >, =, <>, <=, >=

• Logical OperatorsAnd, Or, Not : ('sinusoid' > 50 and 'flow.pv' > 90)

• AdvancedIf …Then …Else, curve(), arma()

TimeGT, FindLT, TagMax, TagAvg, String management …


PI PE ReCalculator• PI Recalc module can update the calculations when historical data is

modified, added, deleted or delayed to the PI archive

• Example – Scan based calculation => Tagavg('Sinusoid','*-30m','*',0)

11h30 12h00

1- Archive event is inserted

2- Average value is affected

3- Average value is recalculated


PI PE Recalc• Example – Events based calculation => ('PointA' + 'PointB')

1- New value added to the

archive

2- A new value is calculated

3- Dependent values are also recalcultated

Source 1 (Point A)

Source 2 (Point B)

Calculation result


PI Alarm Subsystem• The alarm subsystem provides the ability to generate and

manage alarms for PI points. PI Alarm is designed to supplement, not replace, the alarm capabilities available from plant control systems. Because PI is frequently used to integrate data from different sources, PI is often used to perform calculations using variables from multiple physical locations or systems.

• Types of alarms supported– Above or below alarm limits (4 levels)

– Equal or different to a certain digital state or string

– Rate of change

• Keeps historical alarm information in PI tags (Alarm conditions, acknowledgment and alarm statistics)


PI Alarm Subsystem Features• Alarm Priorities: Alarms can be organized and prioritized

via 3 priority levels– 1=Alert, 2=Important, 3=Most Urgent

• Acknowledgement status: Alarms can be in one of 3 states:– New, Acknowledged, NotAcknowledged (Missed)

• Alarm Deadband: It is possible to set a threshold for an alarm to go back to Normal state – Example: HI alarm set 80, Deadband=2 => The value of a PI tag

must be 78 or below to remove a high alarm condition

• Alarm Delay: It is possible to set an Alarm delay– Example: HI Alarm set to 80, delay set to 10 min => The value of

the source tag must be above 80 for a period of 10 minutes in order to become in Alarm


PI Alarm Dataflow

Action1

Alarm DigitalState Set

CombinerLogic

Alarmpoint

Sourcepoint Test1

Action4Test4

Action3Test3

Action2Test2

ReferenceTag


PI Alarm View client

PI AlarmView exposes Activex controls that can be used in otherApplications for example PI ProcessBook.

Documents

1 DevNet Unplugged 2002 “Express Your Innovations” Build a Strong Foundation PI Server Applications Martin Jetté, [email protected] OSI Developers Network