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Aspen Real-TimeSPC Analyzer

User’s Manual



Version Number: V7.1January 2009

Copyright (c) 2006 - 2009 by Aspen Technology, Inc. All rights reserved.

Aspen Real-Time SPC Analyzer, Aspen Q, aspenONE, the aspen leaf logo and Plantelligence and EnterpriseOptimization are trademarks or registered trademarks of Aspen Technology, Inc., Burlington, MA.

All other brand and product names are trademarks or registered trademarks of their respective companies.

This document is intended as a guide to using AspenTech's software. This documentation contains AspenTech

proprietary and confidential information and may not be disclosed, used, or copied without the prior consent ofAspenTech or as set forth in the applicable license agreement. Users are solely responsible for the proper use ofthe software and the application of the results obtained.

Although AspenTech has tested the software and reviewed the documentation, the sole warranty for the softwaremay be found in the applicable license agreement between AspenTech and the user. ASPENTECH MAKES NOWARRANTY OR REPRESENTATION, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THIS DOCUMENTATION,ITS QUALITY, PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE.

Aspen Technology, Inc.200 Wheeler RoadBurlington, MA 01803-5501

USAPhone: +(781) 221-6400Toll Free: (1) (888) 996-7100http://www.aspentech.com

http://www.aspentech.com/

http://www.aspentech.com/



Contents iii

Contents1 Introduction.........................................................................................................1

About This Document ..................................................................................... 1

Organization........................................................................................ 1

Intended Audience ............................................................................... 2

Related Documentation................................................................................... 2

Technical Support .......................................................................................... 2

2 Overview..............................................................................................................5

Graphic Display Platforms................................................................................ 5

Real-Time SPC Analyzer Features List ............................................................... 5 Real-Time SPC Data Records, Pre-configured Charts, and Ad Hoc Charts ................ 6

3 SPC Concepts .......................................................................................................9

Pareto Diagrams ............................................................................................ 9

Histograms ................................................................................................... 9

Control Charts ..............................................................................................10

Variable Data Control Charts.................................................................11

XBar Charts........................................................................................11

Alarm Rules........................................................................................14

4 Installation ........................................................................................................15

Installing Real-Time SPC Analyzer ...................................................................15

System Specific Installation............................................................................15

Real-Time SPC records...................................................................................15

Real-Time SPC for Process Explorer Displays .....................................................16

Aspen Real-Time SPC for Process Explorer Task.................................................16

5 Database Configuration......................................................................................17

Alarm Rule Records .......................................................................................17

Configuration......................................................................................18

Comment Records.........................................................................................20

Free Comment Records ........................................................................21

Fixed–Comment Records ......................................................................21

Pareto Records .............................................................................................22

Q_ParetoKeyDef..................................................................................22

Real-Time SPC Data Records ..........................................................................24

Fixed Areas ........................................................................................25

Repeat Areas ......................................................................................25

SPC Variable Records...........................................................................25



iv Contents

6 Aspen Real-Time SPC for Process Explorer.........................................................35

Overview of Real-Time SPC Charts and Records.................................................36

Viewing Real-Time SPC chart Displays....................................................36

Accessing Real-Time SPC Chart Dialog Boxes ..........................................37

Common Features of SPC Chart Displays ................................................38

Ad Hoc and Pre-Configured Charts.........................................................39

Creating Real-Time SPC records ............................................................39

Modifying or Deleting Real-Time SPC records...........................................39

Formulas for SPC Calculations ...............................................................40

Chart Displays in Real-Time SPC for Process Explorer .........................................40

Histograms.........................................................................................40

Standard Deviation Charts....................................................................42

Range ( R) Charts ................................................................................44

XBar Charts........................................................................................46

EWMA Charts......................................................................................48

CUSUM Charts ....................................................................................50

Pareto Charts .....................................................................................51

Autocorrelation Charts .........................................................................52

Dialog Boxes in Real-Time SPC for Process Explorer ...........................................54 Data Table Dialog Box..........................................................................54

Subgroup Details Dialog .......................................................................55

SPC Parameters Dialog.........................................................................57

SPC Control Limits Dialog .....................................................................59

SPC Alarms & Controls Dialog ...............................................................60

Ad Hoc to Q Dialog ..............................................................................60

Aspen Real-Time SPC Analyzer Configuration Utility (Wizard).....................62

Histogram Parameters Dialog................................................................63

Pareto Parameters Dialog .....................................................................65

Alarms in Real-Time SPC for Process Explorer ...................................................65

Viewing Alarms in a Chart.....................................................................65

Viewing Alarm Details ..........................................................................66

How Alarms are Generated, Enabled, and Disabled...................................66

How Alarm Rules are Configured............................................................66

Common Alarm Rules ..........................................................................67

Maps for Real-Time SPC for Process Explorer Data Access to InfoPlus.21...............67

Example Maps for XBarR21...................................................................68

7 Glossary .............................................................................................................73

Index ....................................................................................................................81



1 Introduction 1

1 Introduction

Statistical process control (SPC) techniques are used to improve product

quality while reducing manufacturing costs. Aspen Real-Time SPC Analyzer(Real-Time SPC Analyzer), formerly Aspen Q, is a software package that

allows these techniques to be applied to process data as it is gathered – inreal time.

The Real-Time SPC Analyzer software is layered onto InfoPlus.21,AspenTech’s cell-level information management system. Real-Time SPC

Analyzer’s operator interface is implemented using Aspen Real-Time SPC for

Process Explorer (formerly Aspen Q for Process Explorer).

About This Document

Organization

This document contains the following:Chapter 1 − Introduction − provides a brief overview of the document and a

list of related documentation.

Chapter 2 − Overview – provides an overview of the Real-Time SPC Analyzer

software.

Chapter 3 − SPC Concepts – provides a brief introduction to statisticalprocess control.

Chapter 4 – Installation – describes the general procedures for installing

Real-Time SPC Analyzer on an existing InfoPlus.21 system.

Chapter 5 – Database Configuration – explains how to configure the various

kinds of Real-Time SPC records.Chapter 6 – Real-Time SPC for Process Explorer – describes the Real-TimeSPC Analyzer component for Process Explorer and the various displays

available through Real-Time SPC for Process Explorer.



2 1 Introduction

Intended Audience

This document is intended for users who need to install, configure, and run

Real-Time SPC Analyzer. It assumes a general understanding of InfoPlus.21.

Related DocumentationThe Aspen Real-Time SPC Analyzer User’s Manual is one of a family of

documents available to InfoPlus.21 users. InfoPlus.21 documentationincludes:

Manuals

Aspen InfoPlus.21 Database User’s Manual

Aspen InfoPlus.21 Database Developer’s Manual

Aspen InfoPlus.21 Database API Manual

Aspen Cim-IO User’s Manual

Help Files

Aspen Real-Time SPC for Process Explorer Help (formerly Aspen Q for Process

Explorer Help)

SQLplus Help for InfoPlus.21

Technical SupportAspenTech customers with a valid license and software maintenance

agreement can register to access the online AspenTech Support Center at:

http://support.aspentech.com

This Web support site allows you to:

• Access current product documentation

• Search for tech tips, solutions and frequently asked questions (FAQs)

• Search for and download application examples

• Search for and download service packs and product updates

• Submit and track technical issues

•

Send suggestions• Report product defects

• Review lists of known deficiencies and defects

Registered users can also subscribe to our Technical Support e-Bulletins.These e-Bulletins are used to alert users to important technical support

information such as:

• Technical advisories

• Product updates and releases

http://support.aspentech.com/




1 Introduction 3

Customer support is also available by phone, fax, and email. The most up-to-

date contact information is available at the AspenTech Support Center at

http://support.aspentech.com.





4 1 Introduction



2 Overview 5

2 Overview

Aspen Real-Time SPC Analyzer (Real-Time SPC Analyzer), formerly Aspen Q,

software is a performance management tool that provides capabilities for SPCmonitoring, analysis, and alarming of operating data originating from

InfoPlus.21 information management systems.

Graphic Display PlatformsThe display-oriented features of Real-Time SPC Analyzer (charts, diagrams,

and tabular displays) rely upon a choice of two graphic display platforms,installed as optional components of the Aspen Manufacturing Suite either

individually or combined, as best fits requirements:

• Aspen Process Explorer - An extendable (via add-in modules) graphicdisplay system that is well integrated with the Microsoft Windows

environment and is designed for delivering data collected by InfoPlus.21.

• Real-Time SPC for Process Explorer is an add-in module that allows

you to display Real-Time SPC charts in Aspen Process Explorer.

Real-Time SPC AnalyzerFeatures ListReal-Time SPC Analyzer features the following display-oriented tools foranalyzing process data in the InfoPlus.21 database:

• Histograms

• Pareto charts

•

XBar/ R charts• XBar/ S charts

• Range ( R) charts

• Standard deviation charts

• EWMA charts

• CUSUM charts

• Autocorrelation charts

• Autocorrelation combined with EWMA charts*



6 2 Overview

• XBar combined with range charts*

• XBar combined with standard deviation charts*

• XBar combined with EWMA charts*

• XBar combined with CUSUM charts*

• XBar combined with autocorrelation charts*

*Note: Combinations of chart displays can be accomplished in Real-TimeSPC for Process Explorer by opening two (or more) Real-Time SPC for

Process Explorer (formerly Aspen Q for Process Explorer) documents, thentiling the chart displays in the Process Explorer workspace.

• Adjusting of control limits, CUSUM constants, EWMA constants

• Adjusting of time period, maximum number of points, and other criteriafor Pareto charts, histograms

• Display of process capability and specification limits in histograms

• Plotting of history of control limits changes

• Assignment of fixed format comment to subgroup

Note: Only available for pre-configured charts.

• Entry of free format comment assigned to subgroup

Note: Only available for pre-configured charts.

• Unlimited display of subgroups within a chart

Note: The time window can be restricted or expanded as needed for

desired view, without limit to number of subgroups.

• Designation of one or more subgroup as an outlier, not to be included inlimits calculations

• Tabular display of SPC (XBar, range, standard deviation, EWMA, CUSUM)chart data

• User-defined control chart alarm rules

•

Active alarms for current chart displayed, summarized

• Alarm rules summarized

• Alarm rules disabling / enabling

Real-Time SPC Data Records,Pre-configured Charts, and AdHoc ChartsReal-Time SPC data records are the source of configuration for display ofpre-configured charts. Also, ad hoc charts can be generated, based on

default values.

Real-Time SPC data records, in addition to being the source for pre-configured charts, serve as the configuration for various background

processes (i.e., processes not directly initiated by a chart, or graphic display).These background processes include the following:

• Formation of subgroups from raw data values.



2 Overview 7

• Testing for alarm rule violations as process data is collected.

• Periodic recalculation of process control limits and related SPC values.

A single SPC data record is a record defined by any of the following records:

Q_XBARDef Q_XBARSDef

Q_XBARCSDef Q_XBARCDef

Q_XBAR21Def Q_XBARS21Def

Q_Pdef Q_NPDef

Q_Udef Q_Cdef

For more information about database records used by Real-Time SPC

Analyzer, fields, and mapping, see later sections in the chapters covering “Database Configuration” (SPC Data Records) and “Aspen Real-Time SPC for

Process Explorer” (Maps for Real-Time SPC for Process Explorer Data Accessto InfoPlus.21).



8 2 Overview



3 SPC Concepts 9

3 SPC Concepts

Statistical process control (SPC) programs are implemented to improve

product quality and reduce manufacturing costs. Statistical methods are usedto 1) identify problem areas, 2) stabilize key process variables, and 3)

determine if a process is capable of making product that meets specifications.

Pareto diagrams and histograms are used to identify problem areas and

their key process variables.

Histograms are used to determine whether a process is capable of makingproduct that conforms to required specifications. Additionally, histograms

provide needed information about the integrity of the measured variables.

Various kinds of control charts are used to bring key process variables into

statistical control. Aspen Real-Time SPC Analyzer (Real-Time SPC Analyzer),formerly Aspen Q, takes this idea a step further by applying statistical alarm

rules to process data in the background; that is, even when control chartsare not being viewed by the operator.

Pareto DiagramsPareto diagrams (also known as Pareto charts) are two-axis bar charts. Eachbar generally represents a single problem, and the height of the bar

represents the frequency or impact of the problem. The bars are arranged indescending order of height from left to right. The chart is useful in

distinguishing the "vital few" from the "trivial many" problems which could beaddressed by quality improvement teams. Pareto charts can be useful tools

for graphically depicting these and other relationships. They can help show

where allocating time, human, and financial resources will yield the bestresults.

Pareto charts are often used to focus attention on the most significant quality

problems. Pareto charts also serve to highlight the results of processimprovements.

HistogramsA histogram consists of a series of bars showing the relative frequencydistribution of process data.



10 3 SPC Concepts

Histograms indicate where the process data is centered, how much the

process data varies, and whether or not the process data follows a normal

distribution.

Additionally, histograms may help determine if a process is capable of makingproduct that conforms to specifications.

Control ChartsManufacturing costs can be reduced and product quality can be improved by

analyzing and controlling changes in influential process variables.

Controlling a manufacturing process generally means collecting various

process data. This process data might be a measured quantity, such as atemperature or thickness, or it could be a count of defective products found in

a given lot. Collecting this process data means pulling samples from apopulation or universe of data.

The mean, median, or mode of process data is often used to characterize the

tendency of the data to center about some dimension. The mean or averageof the process data is simply the sum of the measurements taken, divided by

the number of measurements. The median is the value that splits the data in

half so that half the measurements are above the median and half themeasurements are below the median. The mode is the measurement that

occurs most frequently.

The range or standard deviation of process data is often used to characterize

the dispersion of the data. The range is simply the difference between thehighest and the lowest values. The standard deviation is a measure of the

variation among all the values. The standard deviation is particularly useful if

the process data follows a normal distribution (bell–shaped curve).

Process data following a normal distribution can be characterized as follows:• 68.26% of the data falls between the mean and plus or minus one

standard deviations, and

• 95.46% of the data falls between the mean and plus or minus twostandard deviations, and

• 99.73% of the data falls between the mean and plus or minus threestandard deviations.

Not all process data follows a normal distribution. However, if the processdata variations are random, then the averages of sufficiently large subgroups

of process data will follow a normal distribution. This principle is the basis for

control charts.

Measurements are made periodically in small groupings called subgroups.Ideally, all the process data that forms a subgroup should be sampled under

similar process conditions so that any variations are of a random nature. Itwould then be easier to detect and assign causes to process instability. If the

dispersion of values within a subgroup is random, then the differences

between the subgroup means and ranges may indicate that some importantprocess condition has changed.



3 SPC Concepts 11

Random or chance variations in process conditions are normal. For example, a

sufficiently sensitive thermometer in a closed room will be able to detect

slight random temperature changes that have no apparent cause. Attemptingto control such random temperature fluctuations by adding or removing heat

would be futile and counterproductive.

Sometimes, however, variations in process conditions can be traced toassignable causes. For example, perhaps a temperature change in a closed

room has been triggered by the opening of a window. Identifying andeliminating assignable causes of variation results in a process that is said to

be in statistical control.

Control charts are used to distinguish between random and assignable causesof variation. A control chart is constructed by plotting some parameter of

process performance, hereafter called SPC data, along with an upper controllimit line, a central line, and a lower control limit line. The central line of a

control chart usually represents the mean of the subgroups. The upper and

lower control limit lines are usually three standard deviations (3 σ) away fromthe central line.

If no assignable causes of variation exist, 99.7% of the subgroups will fallwithin the control limit lines. The remaining 0.3% are false alarms. However,this is such a low percentage that subgroups that violate the control limits

generally indicate the presence of an assignable cause.

Variable Data Control ChartsSPC data that is measured (temperatures, weights, thicknesses) is called

variable data. It is used to determine if a measured process variable ischanging normally. Variable data is collected in subgroups of one or more

process measurements.

XBar ChartsThe XBAR chart is one of the most useful for tracking and identifying causes

of variation. The XBAR chart is a continuous plot of subgroup averages. Each

point plotted is the average of the values used to form the subgroup. Thesubgroup size ranges from 1 to 31 for XBAR/R charts and from 10 to 31 for

XBAR/S charts when using pre-defined SPC variables. Ad hoc variables have

neither of these restrictions but it can be difficult to derive useful standarddeviation numbers from small subgroup sizes.

R Charts

The R chart is a continuous plot of subgroup ranges. Each point plotted is thedifference between the largest and smallest value for each subgroup.

S Charts

The S chart is a continuous plot of subgroup standard deviations. Each point

plotted is the standard deviation of the values used to form the subgroup.



12 3 SPC Concepts

Individual Control Charts

Sometimes it is not practical to form a subgroup from multiple

measurements. Real-Time SPC Analyzer provides a choice of threemechanisms for processing individuals; that is, subgroups based on only one

sample measurement. These three mechanisms are:

•

Artificial ranges method• Estimated sigma method

• Moving average, moving range method

Artificial ranges method

Sometimes called moving ranges, the individual measurement is taken as thesubgroup mean. The subgroup range is considered the absolute difference

between the current individual measurement and the previous individualmeasurement. Control limits are calculated based on the average mean and

average artificial range of many subgroups. A range chart constructed forartificial ranges may show one less subgroup than the corresponding XBAR

chart.

Estimated sigma method

Control limits are calculated from the calculated mean and standard deviation

of many individual measurements.

Moving average, moving range method

Subgroups are formed for each measurement using the last N measurements.

For example, using the following samples 3, 5, 6, 2, 8, 9, 1, 10 and N = 5,then:

• Subgroup 1 contains 3, 5, 6, 2, 8




CUSUM Charts

A cumulative summary (CUSUM) chart plots the accumulated deviations ofeach subgroup’s average from the mean or target value. Both the positive

and negative CUSUM values are plotted on a CUSUM control chart along with

upper and lower limit lines. The calculated CUSUM values are normalized sothe charts appear similar for all variables.

The positive CUSUM value increases when the XBAR value is greater than thespecified range above the target and decreases when the XBAR value is within

or below the specified range. Likewise, the negative CUSUM value is

calculated in the same manner for values below the specified range aroundthe target. The calculated CUSUM value is clamped so that it never goes

below zero (or above zero for the negative CUSUM).



3 SPC Concepts 13

EWMA Charts

The EWMA chart is similar to an XBAR chart except that it plots the

exponentially weighted moving average for each subgroup. A smoothingfactor (λ) can be adjusted to assign more or less importance to older

subgroups. Upper and lower EWMA limits are calculated from the standard

deviation of the EWMA values. The EWMA, if properly tuned, can respondmore quickly to process deviations than XBar or CUSUM charts.

Auto–correlation

An auto–correlation chart shows the coefficient of correlation for XBAR values

separated by a user-selectable range. This can be used to determine if the

subgroups appearing on a chart are independent and therefore suitable foranalysis with traditional SPC techniques.

Combination Charts

Combination charts are formed by displaying one type of chart above another.Typical combination charts include XBAR/R, XBAR/S, XBAR/EWMA,XBAR/CUSUM, Auto–correlation/XBAR, and Auto–correlation/EWMA. Control

chart displays may be arranged in any desired format.

np Data

The number of defective units within a lot is represented by np. np plots are

typically used where the sample size is constant. Except for plotting the

number of defective items instead of the proportion of those items, this chartis the equivalent of a p chart.

For example, three defective items found in a lot consisting of 100 items

results in an np of 3 for the lot.

p Data

The proportion of defective units within a lot is represented by p. p plots are

typically used where the sample size is variable.

For example, three defective items found in a lot consisting of 100 itemsresults in a p of 0.03.

c Data

The number of non–conformities in an inspection lot of constant sample sizeis represented by c. A defective item may have more than one non–

conformity. A c may contain more.

For example, a sample of 10 items chart usually has one item per subgroupbut containing 25 defects results in a c of 25.



14 3 SPC Concepts

u Data

The average number of nonconformities per unit in an inspection lot ofvariable sample size is represented by u. u is calculated by dividing the

number of non–conformities by the sample size. The u chart is similar to the c

chart except that the subgroup size varies from subgroup to subgroup.

For example, a sample of 10 items containing 25 defects results in a u of 2.5.

Alarm RulesReal-Time SPC Analyzer automatically generates real–time SQC alarms as

subgroups are created. The various subgroup values, means, ranges, CUSUM,etc., are validated against the alarms enabled for the record being processed.

For any given variable or attribute data, a subset of the user–defined alarmsmay be enabled.



4 Installation 15

4 Installation

Details of an Aspen Real-Time SPC Analyzer (Real-Time SPC Analyzer),

formerly Aspen Q, installation are described in each of the following sectionsof this chapter:

• Installing Real-Time SPC Analyzer

• System–Specific Installation

• Real-Time SPC records

• Real-Time SPC record Configuration

• Real-Time SPC for Process Explorer Displays

•

Real-Time SPC for Process Explorer Task

Note: Real-Time SPC Analyzer requires InfoPlus.21 and Process Explorer.

Installing Real-Time SPCAnalyzerReal-Time SPC Analyzer must be installed on the same host computer as

InfoPlus.21.

Installing Real-Time SPC Analyzer involves the following steps:

1 Running a system–specific installation procedure.

2 Loading the Real-Time SPC records into the InfoPlus.21 database.

3 Installing Real-Time SPC for Process Explorer displays.

System Specific InstallationSee the Aspen InfoPlus.21 Installation Guide for instructions to install

InfoPlus.21 on the target host computer.

Real-Time SPC Analyzer is distributed with InfoPlus.21. The installationprocedure moves the software to the appropriate directories.

Real-Time SPC recordsReal-Time SPC records are loaded into the InfoPlus.21 database automaticallywhen the installation is licensed for Real-Time SPC Analyzer and the default

load files are selected.



16 4 Installation

If it is necessary to load the Real-Time SPC records manually, load the file

newcimq21.rld from the Records tab of the InfoPlus.21 Utilities tool,

available in the InfoPlus.21 Manager folder.

Some Real-Time SPC records contain references to GCS records fromCIMGCS.RLD. This document assumes records from CIMGCS.RLD have

already been loaded into the database.

Real-Time SPC for ProcessExplorer DisplaysReal-Time SPC for Process Explorer displays are distributed with InfoPlus.21.

The displays are provided in ASCII format and are located in the following

directory:

…\AspenTech\InfoPlus.21\db21\displays

Aspen Real-Time SPC forProcess Explorer TaskAspen Real-Time SPC for Process Explorer has a task named TSK_CIMQ which

must run to create subgroups for the Real-Time SPC records. This task isautomatically added to the task list of the InfoPlus.21 manager during the

InfoPlus.21 installation when licensed for Aspen Real-Time SPC Analyzer.

If it is necessary to create the Aspen Real-Time SPC for Process Explorer task

manually, use the InfoPlus.21 manager to add TSK_CIMQ to the InfoPlus.21

task list, and provide the following information:

• Executable is: …\AspenTech\InfoPlus.21\db21\code\cimq.exe

• Task name is TSK_CIMQ

• Select the check box for external tasks and Auto restart.



5 Database Configuration 17

5 Database Configuration

The following sections describe the assorted Real-Time SPC database records

required to fully utilize the capabilities of the Aspen Real-Time SPC Analyzer(formerly Aspen Q) product. As an aid to understanding the Real-Time SPC

records, an example of each is provided. In addition, the steps necessary toproperly configure each record are presented.

Alarm Rule RecordsAspen Real-Time SPC Analyzer allows up to 32 different user–defined control

chart alarm rules for XBAR/R data, XBAR/S data, or attribute data. Each of

these three groups can have its own set of up to 32 alarm rules.

The user defined alarm rules for XBAR/R data, XBAR/S data, and attribute

data are defined in the InfoPlus.21 records Q_XR_ALARM_RULES,Q_XS_ALARM_RULES, and Q_A_ALARM_RULES, respectively.

All three alarm rule records are similar, with each containing a repeat area ofup to 32 occurrences. Q_XR_ALARM_RULES is shown below with its repeat

count set to one.

0 1st_SELECTION_VALUE

Q_XR_ALARM_RULES NAME

NO Q_LOCK_RECORD

Q_XR_RULE_TYPES VALUE FORMAT

1 #_OF_SELECTIONS

1 MEAN HIGH 1 SELECT_DESCRIPTION

Mean Above Upper Control Limit(UCL) line !

1 Q_ALARM_DESCR

RUN 1 Q_ALARM_TYPE

1 1 Q_COUNT1

1 1 Q_COUNT2

1.0000 1 Q_ZONE1

+++++++ 1 Q_ZONE2ON 1 Q_ACTIVE SW.

13–OCT–92 15:56:00.7 1 LAST_UPDATE

The Real-Time SPC Analyzer program that processes the control charts

retrieves the alarm rules from the appropriate alarm rule record every time acontrol chart display is invoked. This guarantees that the specific alarms

associated with the selected record will be used to generate the alarms found

on the control chart.



18 5 Database Configuration

TSK_CIMQ, the background task that generates real–time alarms, examines

each of the three alarm rule records at process start–up. The alarm rules are

stored in internal buffers for use in generating any real–time alarm that mayoccur. The user may change or add to any user–defined alarm while

TSK_CIMQ is active. Once the modification is complete, changing the

Q_LOCK_RECORD field to YES will cause TSK_CIMQ to re–read the alarm

rules. TSK_CIMQ now uses the new alarm rules in any future processing.

Configuration

The following fields must be configured to activate alarming:

Q_LOCK_RECORD

This field controls whether any of the configurable fields in the alarm rulerecord can be modified by the operator. The user must enter or select NO

before attempting to modify any further fields. After all modifications arecomplete, the user must enter or select YES in order for the alarms to take

effect.

#_OF_SELECTIONS

This field is the repeat count field that controls the number of alarm rules that

can be defined. Enter a number between 1 and 32. If a value greater than 32

is entered, the Real-Time SPC processes will only recognize the first 32 alarmrules.

SELECT_DESCRIPTION

This field contains the character string to be used by Real-Time SPC Analyzerto identify the alarm rule in Real-Time SPC data records and on various

displays.

Q_ALARM_DESCR

This field contains a description of the alarm rule. The description appears onthe Alarm Rules Display and identifies which rules are enabled or disabled for

the data appearing on a control chart.

Q_ALARM_TYPE

This field defines the alarm rule type. The following alarm rule types areavailable:

•

UNDEFINED – Initial state before the type has been set.• RUN – A violation occurs when Q_COUNT1 out of Q_COUNT2 subgroups

reside in an alarm zone defined by Q_ZONE1 and Q_ZONE2. There are

additional special rules for specific types of alarm detection related to the

RUN rule that are explained below.

• DOWNTREND – A violation occurs when Q_COUNT1 minus one

consecutive subgroups are at a lower position on the chart than theprevious subgroup.




• UPTREND – A violation occurs when Q_COUNT1 minus one consecutive

subgroups are at a higher position on the chart than the previous

subgroup.

• CUSUM HIGH – A violation occurs when a subgroup’s CUSUM values

exceeds the CUSUM chart high limit.

• CUSUM LOW – A violation occurs when a subgroup’s CUSUM value is lessthan the CUSUM chart low limit.

• EWMA HIGH – A violation occurs when a subgroup’s EWMA valueexceeds the EWMA chart high limit.

• RUN R – Same as RUN but applies to an R chart.

• RUN S – Same as RUN but applies to an S chart.

• DOWNTREND R – Same as DOWNTREND but applies to an R chart.

• DOWNTREND S – Same as DOWNTREND but applies to an S chart.

• UPTREND R – Same as UPTREND but applies to an R chart.

• UPTREND S – Same as UPTREND but applies to an S chart.

Q_COUNT1/Q_COUNT2For a trend rule, Q_COUNT1 contains the number of consecutive ascending

or descending subgroups required for a violation.

For a run rule, Q_COUNT1 out of Q_COUNT2 subgroups in thecorresponding alarm zone are required for a violation.

Q_COUNT1 and Q_COUNT2 have no significance for the other types ofalarm rules.

Q_ZONE1/Q_ZONE2

The run rule is defined by the control limits and the mean. The zones indicate

a multiplier for both control limit and which control limit is tested against themean.

For a run rule, Q_ZONE1 and Q_ZONE2 define the boundaries of the

corresponding alarm zone.

If Q_ZONE1 is positive, it represents the upper zone boundary as thedistance between the process mean and the upper control limit. If Q_ZONE1

is negative, it represents the upper zone boundary as the distance betweenthe process mean and the lower control limit.

Q_ZONE2 represents the lower zone boundary in the same way. If the userwishes to use positive or negative infinity as a zone, InfoPlus.21 displays

positive infinity as a string of plus ‘‘+” signs and negative infinity as a string

of ‘‘–” signs.If Q_ZONE2 is positive infinity , it represents that the tests are for values

above the mean. If Q_ZONE2 is negative infinity then the tests are for values

below the mean.

The run rule can also be used to define a band around the mean wheresubgroup values can be tested to be inside or outside the defined band. This

is specified when neither Q_ZONE1 nor Q_ZONE2 are set to infinity.Q_ZONE1 and Q_ZONE2 then define the upper and lower limits around the




mean and the rule is processed like any other run rule. This “banding” test

can be used to test for values within the band or outside of the band.

If Q_ZONE1 is greater than Q_ZONE2 then the test determines if the values

are outside the band. If Q_ZONE1 is less than Q_ZONE2 then the testdetermines if the values are inside the band.

The following are examples of Q_ZONE1 and Q_ZONE2 settings:Example 1:

To test for values 1 σ above the mean where the upper control limit is 3 σ.Q_ZONE1 would be set to 0.33333 and Q_ZONE2 would be set to positive

infinity (+++++++).

Example 2:

To test for values 1.5 σ below the mean where the lower control limit is 3 σ.Q_ZONE1 would be set to 0.5 and Q_ZONE2 would be set to negative

infinity (-------).

Example 3:

If the process mean is 100.0, the upper control limit is 150.0, Q_ZONE1 is

1.0, and Q_ZONE2 is 0.5, then the alarm zone boundaries are 150.0 and

125.0.

Example 4:

If the process mean is 100.0, the lower control limit is 50.0, Q_ZONE1 is -

0.5, and Q_ZONE2 is negative infinity, then the alarm zone is the entireregion below 75.0.

Example 5:

Testing for a band around the mean is done by setting the zone factors

positive and negative. Setting Q_ZONE1 to 0.33333 and Q_ZONE2 to -0.33333 tests for values outside of a 1 σ band on either side of the mean.

Example 6:

Testing for values inside a band around the mean is done by setting thezone factors negative and positive. Setting Q_ZONE1 to -0.33333 and

Q_ZONE2 to 0.33333 tests for values inside a 1 σ band on either side of

the mean.

ACTIVE SW.

This field indicates ON if Aspen Real-Time SPC Analyzer should generate

alarms when violations of the rule occur; otherwise, the ACTIVE SW. fieldindicates OFF.

Comment RecordsThe Subgroup Detail Display allows the user to assign two types of comments

to a subgroup. A free–format comment of up to 64 characters and a fixed orcanned comment can be selected from a user–defined list of comments.




Every SPC data record contains a reference to a fixed comment record that

specifies the set of canned comments available for assignment to data

samples. The fixed comment record also contains the name of a freecomment record. The free comment record is used as storage for 64–

character free–format comments.

Some or all SPC data records can reference the same fixed–comment record.Similarly, some or all fixed comment records can reference the same free

comment record.

Free Comment Records

Free–format comments are 64–character strings that may be assigned to aparticular subgroup from the Subgroup Detail Display. The comment itself is

not stored with the subgroup data. It is stored in a free–comment record. Thecorresponding comment entry time, generated when Real-Time SPC Analyzer

stores the character string in a history repeat area, is stored with thesubgroup data. It is this time that is used to locate and link the free comment

to the subgroup.

Free comment records are defined by Q_FreeComm21Def for Process

Explorer.

An example of a free–comment record is shown below with its repeat count

set to 1.

FreeComms NAME

Q Free Comment Record DESCRIPTION

Changed paper vendor to ACME ! VALUE

21 HIST SEQUENCE NUMBER

250 NUMBER OF DISK VALS

1 Q_#OF_FREE_FORM_COMMS

Changed paper vendor to ACME ! 1 Q_FREE_FORM_COMMENT

Configuration

The following fields must be configured to activate the free–comments record:

Q_#OF_FREE_FORM_COMS

This field contains the number of free–format comments to be kept in

memory. This field cannot be set to 0 when NUMBER OF DISK VALS is non-zero.

NUMBER OF DISK VALS

This field contains the number of free–format comments to be kept on disk.

This field cannot be changed when Q_#OF_FREE_FORM_COMS is 0.

Fixed–Comment RecordsA Fixed–comment is an integer value that may be assigned to a particular

subgroup from the Subgroup Detail Display. The integer is formatted by a




special select descriptor record called a fixed–comment record. The fixed

comment is selected from among any of the comments predefined in the

fixed–comment record.

Fixed comment records are defined by Q_FixedCommDef . An example of afixed–comment record is shown below with its repeat count set to 1.

FixedComms NAME

Q Fixed Comments Record DESCRIPTION

FreeComms Q_FREE_COMMENT_REC

-1 1ST_SELECTION_VALUE

1 Q_#OF_FIXED_COMMS

Shift change ! 1 Q_FIXED_COMM

Configuration

The following fields must be configured to activate the fixed comments

record:

Q_FREE_COMMENT_REC

This field contains the name of a free–comment record.

1ST_SELECTION_VALUE

This field indicates the integer value to be associated with the first

occurrence. Generally, it is left as 0.

Q_#OF_FIXED_COMMS

This field indicates the number of fixed comments to be defined.

Q_FIXED_COMM

This field contains a 64–character comment. The default comment, with an

integer value of 0, should be left blank.

Pareto RecordsA Pareto record specifies a set of categories that are represented by bars on aPareto diagram. Pareto records are defined by either Q_ParetoKeyDef or

Q_ParetoNoKeyDef .

Note: Q_ParetoKeyDef is the only record enabled for use with Process

Explorer.

Q_ParetoKeyDefA record defined by Q_ParetoKeyDef references a history repeat area thatcontains the raw data to be included on a Pareto diagram.




Suppose, for example, that each time a machine generates waste material,

the amount of waste and the machine id are recorded in a record,

SCRAP_EVENTS, containing multiple occurrences of three fields:SCRAP_WEIGHT, MACHINE_ID, and RECORDING_TIME.

Creating the following Pareto record, defined by Q_ParetoKeyDef , would

allow the scrap production to appear on the Pareto Diagram Display.

ScrapPareto NAME

Scrap Production by Machine DESCRIPTION

Pounds ENG UNITS

SCRAP_EVENTS 1 MACHINE_ID Q_KEY

MACHINE–NAMES Q_SELECT_DESC_REC

SCRAP_EVENTS 1 SCRAP_WEIGHT TREND VALUE

SCRAP_EVENTS 1 RECORDING_TIME TREND TIME

When the Pareto Diagram Display is invoked, Real-Time SPC Analyzer

searches through the specified history repeat area, looking for occurrences in

a specified time range.

For Pareto charts displayed in Process Explorer, all occurrences are evaluated.

The key value and the trend value are read from each such occurrence. In

this example, the key value would be read from the MACHINE_ID field andthe trend value would be read from the SCRAP_WEIGHT field.

Real-Time SPC Analyzer assigns each occurrence to a category based on its

key value. A running total of trend values and an occurrence count bothincrease each time Real-Time SPC Analyzer assigns another occurrence to the

category. After all occurrences have been examined, Real-Time SPC Analyzer

draws a Pareto diagram showing either the trend value total or the occurrencecount of the most significant categories.

ConfigurationThe following fields must be configured to activate the Pareto key record:

DESCRIPTION

This field contains a meaningful description. The character string entered will

also appear on the Pareto Diagram Display.

ENG UNITS

This field indicates the unit of measurement associated with the field referred

to by the TREND VALUE. ENG UNITS is an integer field formatted by the

select descriptor record ENG-UNITS.

Q_KEY

This field refers to an integer field in the specified records history repeat area.

TREND VALUE

This field refers to an integer field in the same repeat area as Q_KEY.




TREND TIME

This field refers to a timestamp field in the same repeat area as Q_KEY.

Q_SELECT_DESC_REC

This field contains the name of a special Pareto select descriptor recorddefined by Q_FixedCommDef . This Pareto select descriptor record contains

an additional field to point to the free comment record. Real-Time SPC

Analyzer will assign descriptions to the various categories by extracting theappropriate character string from this select descriptor record. Normally all

occurrences of the key value fields in the history repeat area are formatted bythe same select descriptor record. The selector’s description can be from 1 to

32 characters.

Configuration

The following fields must be configured to activate the Pareto no-key record:

DESCRIPTION


also appear on the Pareto Diagram Display.

ENG UNITS

This field indicates the unit of measurement associated with the field referredto by the TREND VALUE. ENG UNITS is an integer field formatted by the

select descriptor record ENG-UNITS.

Q_#OF_LABELS

This field is a repeat count field that controls the number of categories thatcan be defined. Enter a number between 1 and 300.

Q_CATEGORY_DESC

This field describes the category. The character string entered will also appear

on the Pareto Diagram Display. This string is limited to 32 characters.

TREND VALUE

This field refers to an integer field in the same repeat area as Q_KEY.

TREND TIME

This field refers to a time-stamp field in the same repeat area as Q_KEY.

Real-Time SPC Data RecordsA Real-Time SPC data record is defined by:




• Q_XBARDef

• Q_XBARSDef

• Q_XBARCDef

• Q_XBARCSDef

• Q_XBAR21Def

•

Q_XBARS21Def

Real-Time SPC data records enable Real-Time SPC Analyzer to form

subgroups and generate Real-Time SPC Analyzer alarms as data is collected

in the InfoPlus.21 database.

Fixed AreasThe fixed areas of Real-Time SPC data records answer various questions for

Real-Time SPC Analyzer such as:

• What is the size of a subgroup?

• How should subgroups of only one value be handled?

•

Where is the raw data used to form subgroups?

• When should subgroups be formed?

• How and when are control limits calculated?

• If there are specification limits, what are they?

• What EWMA and CUSUM constants should be used?

• What integer field, if any, in the InfoPlus.21 database should be set to 1

when an alarm violation occurs?

Note: This would be used to trigger a change of state that could be usedfor alarm notification.

Repeat AreasAll Real-Time SPC data records contain the following three repeat areas:

• A repeat area of alarm rules selected for the Real-Time SPC data record.Real-Time SPC Analyzer checks for violations of the selected alarm rules

whenever it forms a new subgroup.

• A repeat area containing a history of control limits for the Real-Time SPCdata record. Whenever control limits change, the new control limits are

shifted into this history repeat area. Real-Time SPC Analyzer’s controlcharts can then show a history of the control limits.

• A repeat area containing information about each subgroup generated .Real-Time SPC Analyzer shifts a new occurrence of subgroup information

into this repeat area each time a subgroup is formed.

Records defined by Q_XBARDef , Q_XBARSDef , Q_XBARCDef ,Q_XBARCSDef , Q_XBAR21Def , and Q_XBARS21Def contain an additional

repeat area where raw data can be stored.

SPC Variable RecordsXBAR/R records are defined by the following:




• Q_XBARDef

• Q_XBAR21Def

—and—

• Q_XBARCDef

XBAR/S records are defined by the following:

•

Q_XBARSDef

• Q_XBARS21Def

—and—

• Q_XBARCSDef

Records defined by Q_XBARCDef , Q_XBAR21Def , Q_XBARS21Def , andQ_XBARCSDef store CUSUM values in historical repeat areas. This enables

CUSUM background and foreground processing to be directly correlated.

In contrast, CUSUM values are not directly correlated for records defined byQ_XBARDef and Q_XBARSDef .

Note: If CUSUM charts are important to your quality program, it is

recommended that you avoid the use of Q_XBARDef and Q_XBARSDef .

PLANT AREA

TXBAR NAME

Test Sample XBAR Record Description

FixedComms Q_FIXED_COMMENTS

F 7.4 VALUE FORMAT

8 Q_STD_SUBGROUP_SIZE

NO Q_ALLOW_PARTIALS?

ESTIMATED SIGMA Q_INDIVIDUALS_METHOD

0 Q_NUM_MOVING_AVG

51.345 VALUE09–DEC–93 16:55:48 LAST_UPDATE

TREND_VALUE_FIELD

TREND_TIME_FIELD

Q_TRIGGER_FIELD

???????????????????? SCHEDULE_TIME

+000:00:00.0 RESCHEDULE_INTERVAL

0 Q_SUBGROUP_INTERVAL

NO Q_FORM_SUBGROUP?

All Limits User–Specified Q_LIMIT_UPD_TRIGGER

52.45 Q_MEAN_ESTIMATE

1.6500 Q_STD_DEV_ESTIMATE

50 Q_SBGRPS_BEFORE_CALC

45 Q_LIM_RECALC_PERIOD

45 Q_SUBGROUPS_IN_CALC

53.50 Q_LIMIT_UCL

51.00 Q_LIMIT_MEAN

48.50 Q_LIMIT_LCL




3.50 Q_LIMIT_UCL_R (Q_LIMIT_UCL_S)

2.00 Q_LIMIT_MEAN_R (Q_LIMIT_MEAN_S)

0.50 Q_LIMIT_LCL_R (Q_LIMIT_LCL_S)

52.45 Q_STD_DEV

02–DEC–93 15:11:53 Q_LIMIT_LAST_UPD

YES Q_MOVE_LIMITS54.00 Q_USL

47.00 Q_LSL

3.200 Q_EWMA_ALARM_FACTOR

0.700 Q_EWMA_SMOOTHING

3.7500 Q_CUSUM_ALARM_LIMIT

0.250 Q_CUSUM_PRELOAD

0.400 Q_CUSUM_SLACK

ABSOLUTE Q_LIMIT_BASIS

???????????????????? ACTIVATE_TIME

0 Q_LIMIT_COUNTDOWN

??????? Q_CUSUM_ABOVE

??????? Q_CUSUM_BELOW

??????? Q_EWMA

NO Q_TIME_TO_FORM_SBGRP

1022 Q_VALUES_NEEDED

185 Q_VALUES_AVAILABLE

YES Q_MOVE_SUBGROUPS

0 Q_ALARM_RESET_SIGNAL

6 Q_LIMITS_SEQ_NUMBER

143 Q_SBGRPS_SEQ_NUMBER

1145 HIST SEQUENCE NUMBER50 Q_LIMITS_ON_DISK

350 Q_SBGRPS_ON_DISK

1200 NUMBER OF DISK VALS

DV IN_ALARM Q_ALARM_CONDITION_DV

OFF MESSAGE SW.

NO Q_INIT_ALARMS

NO Q_RESET_CUSUM?

NO Q_MSSD

NO Q_EWMA_FIXED_LIMITS

125.5 Q_EWMA_FIXED_HIGH

115.2 Q_EWMA_FIXED_LOW

1 Q_NUMBER_OF_ALARMS

1 MEAN HIGH 1 Q_ALARM_RULE

OK 1 Q_ALARM_STATE

ON 1 Q_RULE_STATUS

ACK 1 Q_ACKNOWLEDGE

0000 1 Q_ALARMINFO




0 1 Q_RESET_COUNT

1 Q_LIMITS_IN_MEMORY

09–DEC–92 15:15:27 1 Q_HIS_LIMIT_TIME

53.30 1 Q_HIS_UCL

51.00 1 Q_HIS_MEAN

48.50 1 Q_HIS_LCL3.50 1 Q_HIS_UCL_R (Q_HIS_UCL_S)

2.00 1 Q_HIS_MEAN_R (Q_HIS_MEAN_S)

0.50 1 Q_HIS_LCL_R (Q_HIS_LCL_S)

1 Q_SBGRPS_IN_MEMORY

09–DEC–92 16:55:48 1 Q_SUBGROUP_TIME

0 1 Q_FREE_COMMENT

! 1 Q_FIXED_COMMENT

49.189 1 Q_SUBGROUP_VALUE

2.763 1 Q_RANGE

3.2 1 Q_CUSUM_HIGH

0.0 1 Q_CUSUM_LOW

8 1 Q_ACT_SUBGROUP_SIZE

YES 1 Q_USE_IN_LIM_CALCS ?

1 NUMBER OF TREND VALS

09–DEC–92 16:55:48 1 TREND TIME

51.345 1 TREND VALUE

Configuration

The following fields should be configured to allow the CIMQ external task to

process the record:

PLANT AREAS

This field associates the Real-Time SPC record to a particular plant area. The

plant area is an integer field formatted by the select descriptor record PLANT–AREAS.

DESCRIPTION


also appear on various control chart displays.

Q_FIXED_COMMENTSThis field allows the operator to enter a fixed–comment record.

VALUE FORMAT

This field contains an operator–entered format record. The format record

controls the display format of the fields containing floating point values.




Q_STD_SUBGROUP_SIZE

This field contains the number of samples that must be collected to form a

subgroup. A subgroup is one or more individual samples that represent, asnearly as possible, a homogeneous set of conditions. That is, a subgroup is

likely to be made up of a randomly produced set of units representing the

immediate state of the process at the time the sample was selected. Enter avalue between 1 and 31 for XBAR/R. Enter a value between 10 and 31 for

XBAR/S.

Q_ALLOW_PARTIALS?

This field tells Real-Time SPC Analyzer if it should form a subgroup even when

there are no Q_STD_SUBGROUP_SIZE new raw data values available. Validresponses are YES or NO.

Q_INDIVIDUAL_METHOD

This field specifies which method for handling individuals should be used. This

field is significant when the Q_STD_SUBGROUP_SIZE is 1. The availableoptions are:

• Estimated Sigma

• Artificial Ranges

• Moving Averages

Q_NUM_MOVING_AVG

This field indicates the number of previous subgroups to use in calculating a

subgroup’s moving average range. The specified numbers of previoussubgroups are averaged for the range value of the current subgroup. It is

only used when the Q_STD_SUBGROUP_SIZE is 1 and the

Q_INDIVIDUAL_METHOD is Moving Averages. Enter a value between 2 and31.

VALUE

Raw data is stored in the Real-Time SPC data record by writing it to theVALUE field. When a new raw data value is written, the LAST_UPDATE field

takes on the current time and both values shift down into a history repeatarea of TREND VALUE and TREND TIME fields. Subgroups are formed out of

data that has shifted into this history repeat area. This is used when it is

desired to keep the raw data values that comprise the subgroups.

TREND_VALUE_FIELDThis field may contain a record and field pointer to raw data values located in

another record’s history repeat area.

If the operator enters a record and field pointer in this field and theTREND_TIME_FIELD field, subgroups will be formed from this data and not

the data entered in the VALUE field described above. When subgroups are

formed in this method, the raw values are not stored in this records history




repeat area. The correlation of raw values with the subgroup data is

somewhat more complicated in this case.

TREND_TIME_FIELD

This field may contain a record and field pointer to timestamp values located

in the same history repeat area as specified in the TREND_VALUE_FIELD field.When Are Subgroups Formed?

Real-Time SPC Analyzer will form subgroups:

• When triggered by a designated change-of-state as specified in

Q_TRIGGER_FIELD.

• Periodically on a scheduled basis, using scheduling fields in the Real-TimeSPC record (RESCHEDULE_INTERVAL and SCHEDULE_TIME).

• When the required number of raw data values have been collected in the

Real-Time SPC data record (specified in Q_STD_SUBGROUP_SIZE).

• Upon demand, either programmatically or on operator demand.

Q_TRIGGER_FIELD

If subgroups are to be formed on a change-of-state condition, this field

should reference the InfoPlus.21 database field used to trigger the activation.

RESCHEDULE_INTERVAL

If Real-Time SPC Analyzer is to form subgroups periodically, the time periodfor subgroup formation should be entered in this field. The time for the next

subgroup formation should be entered in the SCHEDULE_TIME field.

SCHEDULE_TIME

This field is associated with the RESCHEDULE_INTERVAL field. The time for

the next subgroup formation should be entered in this field when Real-TimeSPC Analyzer is to form subgroups periodically. If the reschedule interval is

not set then only one subgroup will be formed when this time is reached.

Q_SUBGROUP_INTERVAL

If Real-Time SPC Analyzer is to form a subgroup when a certain number ofraw data values have been collected, then the number of raw data values

required should be entered in the field. This option requires the raw data

values to be collected in this Real-Time SPC data record. They cannot residein another record.

Q_FORM_SUBGROUP?

Provided enough raw data is available, Real-Time SPC Analyzer will form asubgroup on demand whenever YES is entered in this field.

When Do Control Limits Change?

Control limits can be:

• Manually entered with user–specified limits.




• Calculated once by Real-Time SPC Analyzer based on a user–specified

known mean and standard deviation.

• Calculated periodically. The first time, based on a user–specified estimateof the mean and standard deviation, then periodically, based on the

means and ranges of subgroups previously formed.

Q_LIMIT_UPD_TRIGGER

This field indicates which of control limit change mechanisms has beenselected. The valid selections are:

• All Limits User–Specified

• Calculate Once Using CIMQ_MEAN

• Recalculate Periodically

If Q_LIMIT_UPD_TRIGGER is set to All Limits User-Specified , the followingfields must have already been entered:

• Q_LIMIT_UCL – This field contains the upper control limit line value.

• Q_LIMIT_MEAN – This field contains the mean centerline value.

•

Q_LIMIT_LCL – This field contains the lower control limit line value.

• Q_LIMIT_UCL_R – This field contains the range (standard deviation)

upper control limit line value.

• Q_LIMIT_MEAN_R – This field contains the range (standard deviation)centerline value.

• Q_LIMIT_LCL_R – This field contains the range (standard deviation)lower control limit line value.

• Q_MOVE_LIMITS – Enter a YES to move the limits into theQ_LIMITS_IN_MEMORY history repeat area for control limits.

• Q_STD_DEV – This is the standard deviation of the XBAR values used to

compute the control limits. This value is only updated by Real-Time SPC

Analyzer if the limits are set to be recalculated periodically. If the limitsare user specified then this is where the standard deviation for the limits

calculation is stored.

If Q_LIMIT_UPD_TRIGGER is set to Calculate Once Using CIMQ_MEAN , thefollowing fields must have already been entered:

• Q_MEAN_ESTIMATE – This field contains the estimated process mean.

• Q_STD_DEV_ESTIMATE – This field contains the estimated process

standard deviation.

If Q_LIMIT_UPD_TRIGGER is set to Recalculate Periodically , the followingfields must be entered:

• Q_MEAN_ESTIMATE – This field contains the estimated process mean.

• Q_STD_DEV_ESTIMATE – This field contains the estimated processstandard deviation.

• Q_SBGRPS_BEFORE_CALC – This field indicates the number of

subgroups that must be formed before the first recalculation. This field iseffective when Calculate Once Using CIMQ_MEAN orRecalculate Periodically is selected as the control limits calculation

method.




• Q_LIM_RECALC_PERIOD – This field controls how often subsequent

control limit recalculations will occur when Recalculate Periodically is

selected. Subsequent control limit calculations will occur periodically whenadditional Q_LIM_RECALC_PERIOD subgroups have been formed.

• Q_SUBGROUPS_IN_CALC – This field controls how many subgroups are

considered when control limits are calculated based on the means and

ranges of previously formed subgroups.

Note: If Q_SBGRPS_BEFORE_CALC is non-zero andQ_LIM_RECALC_PERIOD is zero, the control limit is calculated twice.

The first calculation is based on the user–specified Q_MEAN_ESTIMATE

and Q_STD_DEV_ESTIMATE. The second calculation is based on themeans and ranges of recent subgroups and occurs when

Q_SBGRPS_BEFORE_CALC subgroups have been formed.

What Are The Specification Limits?

• Q_USL - This field contains the upper specification limit for use inhistogram processing. This value appears on the histogram display.

• Q_LSL - This field contains the lower specification limit for use in

histogram processing. This value appears on the histogram display.

Note: Both the upper and lower specification limits are also required tocompute the Cp, Cpk, Pp, and Ppk statistics that are displayed on the

Process Explorer histogram.

How Are EWMA Values Calculated?

• Q_EWMA_SMOOTHING - This field specifies a smoothing factor that is

used in calculating the EWMA value for each subgroup. A default value of0.8 is used if this field is left undefined.

• Q_EWMA_ALARM_FACTOR - This field specifies an alarm factor used forcalculating the EWMA alarm limits from the standard deviation. A default

value of 3.0 is used if this field is left undefined.

How Are CUSUM Values Calculated?

• Q_CUSUM_SLACK - This field specifies the normalized range about the

target in which the variable should be controlled. The CUSUM values are

the sum of the deviations outside this range. A default value of 0.5 is usedif this field is left undefined.

• Q_CUSUM_PRELOAD - This field specifies a head start value that will be

added to the CUSUM when a deviation is initially detected. The preloadvalue is intended to initiate a “fast initial response” for the CUSUM chart.

A default value of 0.5 is used if this field is left undefined.

• Q_CUSUM_ALARM_LIMIT - This field specifies CUSUM alarm limit.CUSUM values that exceed this limit generate an alarm. A default value of

4.0 is used if this field is left undefined.How are CUSUM’s Values Reset?

• Q_CUSUM_RESET? - Entering YES into this field resets CUSUM values totheir preload values and will acknowledge CUSUM alarms.

Note: CUSUM values are reset when requested from the SPCParameters dialog box. The Q_CUSUM_RESET field is used to trigger

the reset.




• Q_MSSD – This field is only present in the Q_XBAR21Def and

Q_XBARS21Def records. Set this field to YES to cause the standard

deviation to be calculated using the Mean Square Successive Differencemethod. Refer to the ”Formulas” section in the Aspen Real-Time SPC for

Process Explorer Help for information on this method.

• Q_EWMA_FIXED_LIMITS – This field is only present in the

Q_XBAR21Def and Q_XBARS21Def records. Set this field to YES to causethe EWMA charts to disregard the computed limits and use the storedfixed limits defined in the Real-Time SPC record.

• Q_EWMA_FIXED_HIGH – This field is only present in the Q_XBAR21Def

and Q_XBARS21Def records. Set this field to a value higher than theEWMA target.

• Q_EWMA_FIXED_LOW - This field is only present in the Q_XBAR21Defand Q_XBARS21Def records. Set this field to some value lower than the

EWMA target.

How Much Raw Data Should Be Kept?

• NUMBER OF TREND VALS - This field controls the number of raw data

occurrences of TREND VALUE and TREND TIME to be kept in thememory–resident repeat area. This field is 0 if the raw data resides inanother record. The important factor with these numbers is that they be

set to some value above zero and usually at least two. The occurrences

beyond the resident number are rolled out to disk history,

• NUMBER OF DISK VALS - This field controls the number of raw data

occurrences to be kept in a disk history file. This field is 0 (zero) if the rawdata resides in another record. The important factor with these numbers is

that they be set to some value above 0 (zero) and usually at least 2(two). The occurrences beyond the resident number are rolled out to disk

history,

How Many Subgroups Should Be Kept?

•

Q_SBGRPS_IN_MEMORY - This field controls the number of occurrencesof subgroup data to be saved in a memory–resident repeat area. The

important factor with these numbers is that they be set to some valueabove 0 (zero) and usually at least 2 (two). The occurrences beyond the

resident number are rolled out to disk history,

• Q_SBGRPS_ON_DISK - This field determines if subgroup data is storedon disk. This must be set to ON and a positive number must be set into

Q_SBGRPS_IN_MEMORY for subgroup data to be stored.

How Many Sets of Control Limits Should Be Kept?

• Q_LIMITS_IN_MEMORY - This field controls the number of occurrences

of control limits to be kept in a memory–resident repeat area. The

important factor with these numbers is that they be set to some valueabove 0 (zero) and usually at least 2 (two). The occurrences beyond theresident number are rolled out to disk history,

• Q_LIMITS_ON_DISK - This field determines if subgroup data is stored

on disk. This must be set to ON and a positive number must be set intoQ_LIMITS_IN_MEMORY for subgroup data to be stored.

How Are Alarm Rules Enabled?




• Q_NUMBER_OF_ALARMS - This field controls the number of alarm rules

that may be enabled. For an XBAR/R record, the alarm rules enabled is a

subset of the alarm rules enabled in the Q_XR_ALARM_RULES record.Valid entries range from 0 to 32.

• Q_INIT_ALARMS - Setting this field to YES causes Real-Time SPC

Analyzer to initialize various fields in the alarm rules repeat area

(including Q_ALARM_RULE and Q_RULE_STATUS) to values found inthe corresponding occurrences of the Q_XR_ALARM_RULES record. This isa quick way to enable the alarms because it will copy n number of alarms

defined in Q_XR_ALARM_RULES to the repeat area.

• Q_ALARM_RULE - As an alternative to Q_INIT_ALARMS, the desiredrule may be entered in this field manually.

Note: If you use Q_ALARM_RULE to set your alarm rules manually, donot set Q_INIT_ALARMS to YES. If Q_INIT_ALARMS is set to YES,

manually entered alarms are overwritten.

• Q_RULE_STATUS - As an alternative to Q_INIT_ALARMS, setting this

field to ON will enable alarm rule checking for this alarm.

Note: If you use Q_RULE_STATUS and set your alarm rules manually,do not set Q_INIT_ALARMS to YES. If Q_INIT_ALARMS is set to YES,

manually entered alarms are overwritten.

• Q_ALARM_CONDITION_DV - If non–blank, this field specifies adatabase field containing an integer that is set to one when a Real-Time

SPC Q_ALARM_STATE field changes from OK to ALARM.

Should Alarms Be Logged?

• MESSAGE SW. - This field controls whether Real-Time SPC Analyzer

alarm violations and acknowledgements are logged to the Real-Time SPCAlarm History Display and to a logging file or device. Valid responses are

ON and OFF.



6 Aspen Real-Time SPC for Process Explorer 35

6 Aspen Real-Time SPC forProcess Explorer

Aspen Real-Time SPC (Real-Time SPC) for Process Explorer (formerly Aspen Qfor Process Explorer), provides an operator interface that is implemented

using an ActiveX control held by the Aspen Process Explorer, thus expandingthe capabilities of Process Explorer.

Note: See the Aspen Process Explorer Help for information about ProcessExplorer menus, the timeline, and other Process Explorer core functionality.

Real-Time SPC for Process Explorer provides these capabilities for collectingand analyzing statistical process control (SPC) data:

• Application of data rules to customize statistical information

• Display of statistical alarms to detect process flaws

• Display of ad hoc and pre-configured charts to facilitate SPC data analysis

The charts available in Real-Time SPC for Process Explorer include the

following:• Histograms

• Standard Deviation Charts

• Range ( R) Charts

• XBar Charts

• EWMA Charts

• CUSUM Charts

• Pareto Charts

• Autocorrelation Charts

To use the full capabilities of Real-Time SPC for Process Explorer, you must

install Aspen Process Explorer to view Statistical Process Control (SPC) charts.

Note: Real-Time SPC Analyzer and Real-Time SPC for Process Explorer do not

support CIMVIEW products.



36 6 Aspen Real-Time SPC for Process Explorer

Overview of Real-Time SPCCharts and RecordsIn Real-Time SPC for Process Explorer, Real-Time SPC records contain the

controlling parameters for alarm thresholds, collecting SPC data andgenerating pre-configured Real-Time SPC chart displays. Real-Time SPC

charts can also be displayed on an ad hoc basis, in which an SPC chart isdisplayed based on default values.

Viewing Real-Time SPC chart Displays

There are two ways to view ad hoc and pre-configured charts in AspenProcess Explorer. Use the Process Explorer menu commands and controls

listed below to create either a new Real-Time SPC chart or a new plot.

New Real-Time SPC chartTo view a Real-Time SPC chart by creating a new Real-Time SPC

chart:

1 From the Process Explorer menu, select File | New. The New Document dialog box appears.

2 Select the Real-Time SPC tab, then select the type of Real-Time SPC

chart you want to display.

3 Add one or more tags to the plot by placing the cursor in the Name areaof the legend and entering the tag name, or by dropping tags into the

legend from the Tag Browser.




Figure 6-1 Real-Time SPC charts available from the Real-Time SPC tab, NewDocument dialog box

New Plot

To view a Real-Time SPC chart by creating a new Plot:

1 From the Process Explorer menu, select File | New. The New Document dialog box appears.

2 Select the Standard tab, then select Trend, and click OK.

3 From the Process Explorer menu, select Plots | Real-Time SPC.

4 Select the type of Real-Time SPC chart you want to display.

5 Add one or more tags to the plot by placing the cursor in the Name areaof the legend and entering the tag name, or by dropping tags into the

legend from the Tag Browser.

Accessing Real-Time SPC Chart Dialog

BoxesVarious useful dialog boxes can be accessed from the right-click, context

menu available when a Real-Time SPC chart is displayed. To display thecontext menu, right-click on the plot. A pop-up context menu is displayed.

Then, from the context menu, make the appropriate selection.

Depending upon the plot that is currently displayed, these dialog boxes areavailable from selections in the context menu:

• Data Table – Shows the chart information in a data table.

• Subgroup Details – Displays details about individual subgroups and

associated alarms. Also, if the currently charted variable is a properlyconfigured, pre-defined SPC variable, the Subgroup Details dialog box

enables assigning comments to a subgroup and designating one or moresubgroups as outlier subgroups, not to be included in limits calculations.

• SPC Parameters – Enables adjusting of the methods used to gather data

and perform calculations in Statistical Process Control.

• SPC Control Limits – For pre-configured Real-Time SPC records only,controls the display of historical control limits in an SPC chart if limits are

being saved in history. For ad hoc charts, displays only the current control

limits.

• SPC Alarms & Controls – Shows SPC alarms that are currently active,

which Real-Time SPC record is used to define the alarm rules, and whichSPC alarms have occurred in the data currently displayed.

•

Ad Hoc to Q – Enables creating a new Real-Time SPC record from an adhoc chart.

• Histogram Parameters – Enables adjusting of calculation and display

properties of the currently displayed histogram. Also enables changing thehistorical period used to calculate the Pp and Ppk statistics.




Note: Some of the dialog boxes listed above may or may not be available,

depending upon which Real-Time SPC chart is currently displayed. For

example, the Histogram Parameters dialog box is available only if ahistogram is currently displayed. In a similar manner, the SPC Control

Limits dialog is available only if an SPC chart is currently displayed.

Common Features of SPC Chart DisplaysThe SPC chart displays in Real-Time SPC for Process Explorer exhibit these

features that are common to Process Explorer, timeline, legend, and

scooters.

Note: To make adjustments to the SPC chart parameters listed below, accessthe SPC tab in the Options dialog box (select Tools | Options).

Timeline

The standard Aspen Process Explorer timeline is used in Real-Time SPC for

Process Explorer to display the window of time that the data spans.

Controlling elements of the timeline include the global timeline, time slider,

calendar, plot span, and the fixed time span.

Legend

The legend for Real-Time SPC standard control charts is similar to that forother Aspen Process Explorer plots.

The Real-Time SPC chart legend displays:

• Name

• Data Source

• Map

• Description

• Value

• Units

• Level

• Autoscaling

• Plot minimum

• Plot maximum

• Shift

• Time Zone

• Additional parameters appropriate to the type of Real-Time SPC chartdisplayed

Scooters

A scooter is a line (cursor) inserted into the plot that provides a quick way to

view the data values of a pen at a particular point in time.




When scooters are active in a Real-Time SPC chart in Process Explorer, the

value displayed on each scooter is an interpolated value derived from the

subgroups that are adjacent to the scooter.

Ad Hoc and Pre-Configured ChartsReal-Time SPC for Process Explorer supports two modes of SPC charting:

• Ad hoc – Aspen Process Explorer creates the chart using tag data from

history; SPC parameters are taken from a set of default values so a basicchart can be constructed in real time.

• Pre-configured – The control chart is created using SPC variables that

have been defined by Real-Time SPC records in the InfoPlus.21 database.The Real-Time SPC records also include a history repeat area of real-time

SPC statistical calculation results.

Pre-configured charts based on Real-Time SPC records provide many more

capabilities compared to ad hoc charts. This becomes especially evident whenyou view the supporting SPC Parameters dialog, where many chart control

options are unavailable if an ad hoc chart is currently displayed.

Note: Histograms are not computed in Real-Time SPC records but can beused to display data from Real-Time SPC records.

Creating Real-Time SPC recordsReal-Time SPC for Process Explorer offers two ways to create new Real-Time

SPC records (each Real-Time SPC record contains the controlling parametersfor collecting the data and generating a pre-configured SPC chart display):

• Ad Hoc to Q (dialog box) – Enables creating a new Real-Time SPC record

based on the parameters of a currently displayed ad hoc chart.

•

Aspen Real-Time SPC Analyzer Configuration Utility (wizard) –

Displays a ‘wizard’ sequence of dialog boxes so that all the parameters for

defining a new Real-Time SPC record can be specified.

Modifying or Deleting Real-Time SPC

recordsReal-Time SPC for Process Explorer offers a way to modify Real-Time SPC

records by using the Aspen Real-Time SPC Analyzer ConfigurationUtility. If you enter the name of an existing Real-Time SPC record, or

variable in the second wizard dialog (SPC Variable Identification), all the

subsequent dialogs in the wizard sequence will be populated with data fromthe Real-Time SPC record, thus giving you a way to modify the record.

Real-Time SPC records can also be modified by using the InfoPlus.21

administrator tools. Deleting a Real-Time SPC record can only be donethrough InfoPlus.21 administration.




Formulas for SPC Calculations

The mathematical formulas used in Real-Time SPC for Process Explorer to

produce SPC charts and statistics are documented in the Aspen Real-TimeSPC for Process Explorer Help and included in an appendix at the end of this

manual.

Chart Displays in Real-TimeSPC for Process ExplorerEach of the charts available in Real-Time SPC for Process Explorer arediscussed in detail in this section.

Histograms

The histogram is a graphical representation of the distribution of processdata. Each column in a histogram is a bin to collect the count of values that

fall within the bin’s range of values. The width of each column in a histogramrepresents a value range. The height of each column in a histogram

represents the frequency or number of observations in each cell. Histograms

indicate:

• The center of the process data

• Process data variations

• Process data distribution

• Process capability

• Specification limits

•

The normal distribution curveThe following figure shows an example histogram, as displayed in Real-Time

SPC for Process Explorer.




Figure 6-2 Example histogram display in Real-Time SPC for Process Explorer

In addition to the information in the legend, the histogram display indicates:

• # of Bins – Indicates the number of cell divisions displayed on thehistogram. This is how many bins the total number of samples has been

split into for the display. The initial value for this is determined by thetotal number of samples available, but can be adjusted through theNumber of Bins setting in the Histogram Parameters dialog box.

• # of Samples – Indicates the samples processed for the time period.

Note: When a scooter is dropped on a histogram the top bubble displaysthe cell boundary values, and the scooter bubble displays the number of

occurrences within the boundary.

• LPC (Lower Process Capability) and UPC (Upper Process Capability) –

Represent the lower and upper process capability limits, or, essentially, athree sigma band on either side of the mean. LPC and UPC are graphically

represented on the plot window with solid, black vertical lines on either

side of the mean.

Note: LPC and UPC values are approximations based on standard

deviation. A true process capability study is required for precise values.

• LSL (Lower Specification Limit) and USL (Upper Specification Limit) –

Represent the lower and upper process specification limits relative to the

process value. The process capability indices (C p, C pk, P p, and P pk) cannot

be calculated unless LSL and USL values are provided. When a histogram

is generated from Real-Time SPC record data, specification limits are




already defined in the Real-Time SPC record. LSL and USL are graphically

represented on the plot window with vertical dotted lines.

Note: If the specification limits fall outside of the plot window, the vertical

lines may not be visible on the histogram display.

• C p and C pk – Indicate the process capability (C p) and process capability

index (C pk), which are a measure of the ability to produce product withinthe specification limits.

• P p and P pk – Indicate the process potential ( P p) and process potential

index ( P pk), which are a measure of the ability of the process to achieve a

certain level of consistent quality.

Note: P p and P pk process data over a longer period of time than the period

displayed in the plot. This time period is set from the HistogramParameters dialog box.

• Mean – Indicates the population mean, or the average of the observed

data. A dashed vertical line is drawn on the mean.

• Standard Deviation – Indicates the standard deviation (σ ) of the

population.

Histogram Details

Histograms provide a convenient location to view other statistical coefficients

useful for interpreting the validity of process data. For example, you canoverlay a normal distribution curve (also called a Gaussian or bell-shaped

curve) onto the histogram to compare process data with a normal distribution

and to aid in determining whether the data is skewed. (Enable or disableShow Curve in the Histogram Parameters dialog box.)

Data on the histogram is presented as varying bar heights dependent on thenumber of samples that fall within the value range of that bin.

No alarms are generated in a histogram. However, vertical lines overlaid onthe graph show the calculated process capability limits and the process

specification limits. You can set the specification limits in the HistogramParameters dialog box (see later section, “Dialog Boxes in Real-Time SPC for

Process Explorer”).

The vertical scale for a histogram is slightly larger than the largest bin and isdisplayed as a frequency. The horizontal scale is taken from the lowest and

highest values in the data set that fall within the time window, displayed bythe timeline.

Use histograms to help determine whether:

• A process is capable of making a product according to specifications.

•

A process can achieve a certain level of consistent quality.• Data is normally distributed or skewed.

Standard Deviation ChartsThe standard deviation chart is a continuous plot of subgroup standard

deviations. Each point plotted is the standard deviation of the values used toform the subgroup.




The standard deviation of subgroups should be in control before the subgroup

average (XBar) can be effectively addressed.

The following figure shows an example standard deviation chart, as displayed

in Real-Time SPC for Process Explorer.

Figure 6-3 Example standard deviation chart in Real-Time SPC for ProcessExplorer

The plot window for the standard deviation chart displays:

• A graph for the tag – accented with markers:

A blue square indicates the standard deviation of the subgroup in anormal state.

A red triangle indicates the standard deviation of the subgroup in analarm state.

• A red central line indicates the process average (XBarBar).

•

Blue lines above and below the central line indicate the upper and lowercontrol limits.

• Dashed lines around the upper and lower control limit lines indicatehistorical limits. (Optional and only available for a pre-configured chart

defined by a Real-Time SPC record.)




Note: Lines indicating historical limits are enabled or disabled in the SPC

Parameters dialog. Historical limits can be enabled for display only if the

chart is a pre-configured chart and limits are being stored in history, asdefined by a Real-Time SPC record. (See later section, “Dialog Boxes in

Real-Time SPC for Process Explorer.”)

In addition to the information in the legend, the standard deviation chartdisplays:

• XBarBar – Displays the value used to calculate the control limits currentlyin effect.

• Range – Indicates the current average of the ranges used for the display.

• StdDev – Indicates the standard deviation used to calculate the controllimit.

• Subgroup Size – Indicates the number of values in each subgroup(modifiable from the SPC Parameters dialog box only in ad hoc charts).

• Subgroups in Limits – Indicates the number of subgroups that were

used to calculate the control limits (modifiable from the SPC Parameters dialog box only in ad hoc charts).

Note: Real-Time SPC charts show data only from one variable at a time.

If multiple tags (variables) are added to the legend, only the currentlyselected tag is displayed in a Real-Time SPC chart. Multiple variables

cannot be overlaid on the same Real-Time SPC chart.

Tip: The following are recommended for standard deviation:

• Use autoscale.

• Use a subgroup size of at least ten (10) so a reasonable standarddeviation can be derived.

Range ( R) Charts

The range ( R) chart is a continuous plot of subgroup ranges. Each point

plotted is the difference between the largest and smallest value found in asubgroup. Range charts are used to show the magnitude of the spread of the

process you are analyzing, to indicate whether the spread is stable, and toreveal information associated with mixtures, interactions, and various forms

of instability.

The range ( R) of subgroups should be in control before the subgroup average

(XBar) can be effectively addressed.

Note: Range values are always greater than zero.

The following figure shows an example range ( R) chart, as displayed in Real-

Time SPC for Process Explorer.




Figure 6-4 Example range ( R ) chart in Real-Time SPC for Process Explorer

The plot window for the range ( R) chart displays:

•

A graph for the tag – accented with markers:A blue square indicates a subgroup range in a normal state.

A red triangle indicates a subgroup range in an alarm state.

• A red central line indicates the range average ( R Bar).

• A blue line above the central line represents the range chart control limit.(There is no lower control limit for range.)

• Dashed lines around the upper and lower control limit lines indicate

historical limits. (Optional and only available for a pre-configured chartdefined by a Real-Time SPC record.)

Note: Lines indicating historical limits are enabled or disabled in the SPCParameters dialog. Historical limits can be enabled for display only if the


Real-Time SPC for Process Explorer.”)

In addition to the information in the legend, the range ( R) chart displays:

• XBarBar – Displays the value used to calculate the control limit currently

in effect.

• Range – Indicates the current average of the ranges used for thedisplay/used for calculating the control limits.




• StdDev – Indicates the standard deviation used to calculate the control

limit.

• Subgroup Size – Indicates the number of values in each subgroup(modifiable from the SPC Parameters dialog box only in ad hoc charts).

• Subgroups in Limits – Indicates the number of subgroups that were

used to calculate the control limits (modifiable from the SPC Parameters dialog box only in ad hoc charts).

Note: Real-Time SPC charts show data only from one variable at a time.If multiple tags (variables) are added to the legend, only the currently

selected tag is displayed in a Real-Time SPC chart. Multiple variables

cannot be overlaid on the same Real-Time SPC chart.

Tip: Autoscale is recommended for range ( R) charts.

XBar Charts

The XBar chart is useful for tracking and identifying causes of variation.

The XBar chart is a continuous plot of subgroup averages. Each point plottedis the average of the values used to form the subgroup. XBar is calculated

and stored with each subgroup based on configuration of the variable. You

choose the size and type of the subgroup to represent the process at aspecific point in time.

The following figure shows an example XBar chart, as displayed in Real-TimeSPC for Process Explorer. (The example shows pre-defined SPC variable

XBar21/R used for plotting.)




Figure 6-5 Example XBar chart in Real-Time SPC for Process Explorer

The plot window for the XBar chart displays:


A blue square indicates a subgroup average in a normal state.

A red triangle indicates a subgroup average in an alarm state.

•

A red central line indicates the process average, or mean of thesubgroups.

• Blue lines above and below the central line indicate the upper and lower

control limits.

• Dashed lines around the upper and lower control limit lines indicatehistorical limits. (Optional and only available for a pre-configured chart

defined by a Real-Time SPC record.)

Note: Lines indicating historical limits are enabled or disabled in the SPCParameters dialog. Historical limits can be enabled for display only if the


Real-Time SPC for Process Explorer.”)In addition to the information in the legend, the XBar chart displays:

• XBarBar – Displays the value used to calculate the control limits currently

in effect. It is the average of all of the XBar values

• Range – Indicates the current average of all the subgroup ranges values

used for the display.

• StdDev – Indicates the standard deviation used to calculate the controllimits.




• Subgroup Size – Indicates the number of values in each subgroup

(modifiable from the SPC Parameters dialog box only in ad hoc charts).

• Subgroups in Limits – Indicates the number of subgroups that wereused to calculate the control limits (modifiable from the SPC Parameters

dialog box only in ad hoc charts).

Note: Subgroups in ad hoc charts may be recalculated each update cycle.The ad hoc chart attempts to synchronize the recalculation by locating an

anchor data point. If the anchor cannot be found, because of an updatecycle or a change in the timeline, all subgroups are recalculated.

EWMA Charts

An Exponentially Weighted Moving Average (EWMA) chart is similar to an

XBar chart, except it plots the exponentially weighted moving average foreach subgroup.

In the EWMA chart, you can assign more or less importance to oldersubgroups by adjusting the smoothing factor ( λ ). The EWMA, if properly

tuned, has the ability of responding more quickly than XBar or CUSUM toprocess deviations.

The activation of alarms is controlled from the appropriate property sheet and

accompanying SPC Parameters dialog box (accessed from the right-clickcontext menu; see later section, “Dialog Boxes in Real-Time SPC for Process

Explorer”).

The following figure shows an example EWMA chart, as displayed in Real-TimeSPC for Process Explorer.




Figure 6-6 Example EWMA chart in Real-Time SPC for Process Explorer

The plot window for the EWMA chart displays:


A blue square indicates the EWMA value of the subgroup in a normal state.

A red triangle indicates the EWMA value of the subgroup in an alarm state.

Note: EWMA charts are determined to be in alarm when a value exceedsa preset limit. The concept of runs and trends does not apply to EWMA

charts.

In addition to the information in the legend, the EWMA chart displays:


in effect.



limits.


(modifiable from the SPC Parameters dialog box only in ad hoc charts).• Subgroups in Limits – Indicates the number of subgroups used to

calculate the control limits (modifiable from the SPC Parameters dialog

box only in ad hoc charts).

• Lambda ( λ ) (Smoothing Factor) – Determines the memory of the EWMA

statistic. The rate of decay is determined by lambda, which determines

the amount of information used from the historical data.




Note: CUSUM subgroups are determined to be in alarm when a preset

limit is exceeded. The concept of runs and trends does not apply to

CUSUM charts.

• A red central line indicates the CUSUM target. The plotted CUSUM target

will always be zero (0) because the chart is showing the cumulative sum

of the deviation from the mean.

•

Two blue lines, above and below the central line, indicate the upper and

lower control limits.

In addition to the information in the legend, the CUSUM chart displays:


in effect.



limit.



• Subgroups in Limits – Indicates the number of subgroups used tocalculate the control limits (modifiable from the SPC Parameters dialog


• Target – Indicates the population mean value from which deviations aresummed. When the cumulative sum exceeds the limit, an alarm can be

generated. Alarming can be activated for one or both sides of target.

• Slack – Indicates the normalized range about the target in which the

variable should be controlled and the deviation from the target can beignored. The CUSUM values are the sum of the deviations outside this

range.

• Pre-Load – Indicates the ‘head start’ value that is added to the CUSUMthe first time a deviation occurs. This value gives the CUSUM a fast initial

response to deviations.• Alarm Factor – Indicates the alarm factor used to determine how far

from either side of the target the CUSUM will be in an alarm state. CUSUM

values that exceed this limit generate an alarm.

Note: Historical limits for CUSUM cannot be stored in the database.

Pareto Charts

A Pareto chart is not a control chart in the strictest sense, but a chart thatcan be used to identify the order of causes and the relative contribution of the

causes that result in product nonconformities.

The Pareto chart shows a set of bar graphs in descending order, each barrepresenting the frequency of occurrences for an individual cause, or Pareto

category. The Pareto categories that are included in the chart are determined

by the selector record used for the Pareto chart.

The following figure shows an example Pareto chart, as displayed in Real-

Time SPC for Process Explorer.




Figure 6-8 Example Pareto chart in Real-Time SPC for Process Explorer

Annotations located above the plot window of the Pareto chart identify thefollowing:

• Number of Pareto categories

• Total number of samples represented on the chart

Note: Using a scooter on the chart will show the cause code name (or

Pareto category name), the percentage of contribution to the total, alongwith the number of sample counts for the category.

Left and right vertical scales for the chart are in units of:

• Sample counts (left)

• Percentage of total counts (right)

Annotations located underneath the plot window identify all of the Paretocategory names and associated index numbers.

If desired, you can adjust the Starting category and Categories in display by entering values in the Pareto Parameters dialog box (accessed from the

right-click context menu). Changing these values enables display of acategory other than the most prevalent category in the first bar graph, and

limiting the number of bar graphs, or columns displayed. (See later section, “Dialog Boxes in Real-Time SPC for Process Explorer.”)

Autocorrelation ChartsThe autocorrelation chart plots a set of correlation coefficients on a single

data set for several time-lag intervals, helping you to see the consistency andverify the independence of your data over time. Autocorrelation can help you




determine whether the data being examined is truly independent or

correlated to some cyclical event or activity (see further discussion, below, in

“Autocorrelation Details”). Autocorrelation can also be used to assess theperformance of feedback controllers.

The following figure shows an example autocorrelation chart, as displayed in

Real-Time SPC for Process Explorer.

Figure 6-9 Example autocorrelation chart in Real-Time SPC for ProcessExplorer

The auto correlation chart displays a series of vertical bars. Each bar

represents the correlation coefficient between the most recent subgroup and

previous subgroups.

A correlation coefficient ranges from negative one (-1), the maximum degreeof inverse correlation, to positive one (+1), the maximum degree of positive

correlation.

In addition to the information in the legend, the autocorrelation chart display

provides:• XBarBar – Displays the value used to calculate the control limits currently

in effect.


• StdDev – Indicates the standard deviation used to calculate the controllimit.






• Subgroups in Limits – Indicates the number of subgroups used to

calculate the control limits (modifiable from the SPC Parameters dialog


Autocorrelation Details

An autocorrelation chart can help in assessing the validity of standard controlcharts. Standard control charts require that observations from the process areindependent of one another. Failure to meet this requirement increases the

chance that the control chart will indicate a process shift when the process

has NOT shifted (a false alarm). Therefore, the autocorrelation chart is a goodtool to use to check the independence assumption. If control limits on an XBar

chart are particularly tight, with many out of control points, autocorrelationshould be suspected.

If the autocorrelation is only significant at low lags (adjacent data points),

you can increase the time between acquiring data points to lessen its effect.

In other cases, there might be auto correlation due to sampling from multiplestreams in a process. For example, when monitoring order processing times,

if each data point is the time taken by each one of five employees operatingat a different average level, then an autocorrelation would appear at lag 5.

The correlation is presented as a series of bars running negative and positive

from a zero centerline. In the example autocorrelation chart illustrated above,the bars represent the correlation coefficient of the data at various lag

periods. The first bar is with no lag and therefore has a correlation coefficientof 1.0, indicating a direct correlation, as would be expected. Each subsequent

bar indicates the coefficient for that lag period. The bar can be set to turn redif it exceeds some preset limit (default limit is 0.2).

When a scooter is dropped on the autocorrelation chart it will indicate the

actual correlation coefficient and the lag period.

Dialog Boxes in Real-Time SPCfor Process ExplorerThe dialog boxes in Real-Time SPC for Process Explorer enable viewing of

data and alarms, and adjustment of SPC chart and other chart parameters.

To display the dialog boxes described below, right-click while viewing a Real-

Time SPC chart to display a pop-up context menu. Then make an appropriateselection from the context menu.

Data Table Dialog BoxTo view the Data Table dialog box, right-click on the currently displayed

chart, and select Show Data Table from the context menu.

The Data Table dialog box shows the chart information in a data table. Thereis no user input in this dialog box.




The following figure shows an example Data Table dialog box, as displayed

in Real-Time SPC for Process Explorer.

Figure 6-10 Example Data Table dialog in Real-Time SPC for Process Explorer

Note: The Data Table dialog box is not available from these charts:

autocorrelation, Pareto, and histogram.

Subgroup Details Dialog

To view the Subgroup Details dialog box, right-click on the desiredsubgroup in the currently displayed SPC chart (for example, the Standard

Deviation chart, Range [R] chart, XBar chart, and so forth), and selectSubgroup Details from the context menu.

Note: The Subgroup Details dialog box is not available from these charts:autocorrelation, Pareto, and histogram.

The Subgroup Details dialog box displays details about individual subgroups

and associated alarms. Also, if the currently charted variable is a properly

configured, pre-defined SPC variable, the Subgroup Details dialog box enablesassigning comments to a subgroup and designating any one or more

subgroups as an outlier subgroup, not to be included in limits calculations.

The following figure shows an example Subgroup Details dialog box, asdisplayed in Real-Time SPC for Process Explorer.




Figure 6-11 Example Subgroup Details dialog in Real-Time SPC for ProcessExplorer

The top portion of the Subgroup Details dialog box displays statisticsrelevant to the individual subgroup. The bottom portion of the dialog box

includes the following parameters that apply to the individual subgroup:

• Alarms – Displays the description of any active alarm applicable to thesubgroup.

• Do not include subgroup in limits calculations – Check box fordesignating the current subgroup as an outlier subgroup: that is, a

subgroup that is invalid, may introduce inappropriate skewing, and / orshould not be included in calculations for determining control limits.

(Available only in pre-configured charts.)

Notes:

• An outlier subgroup is displayed in the chart with a magenta circle

around the subgroup.

• Because control limits are computed on historical subgroups, if a

subgroup is marked as an outlier prior to limits computation, there will

be no effect. If, however, the subgroup is within the limits computationwindow, it will be excluded on the next limits calculation.

• Fixed Format Comment – Enables selection from a list of available fixed

format comments, which can be used for identifying causal relationshipsfor out of control or significant events for a subgroup. (Available only in

pre-configured charts.)

Notes:

• A subgroup that has either fixed or free format comment(s) attached

is displayed in the chart with a magenta diamond around thesubgroup.

• Fixed format comments are particularly useful as input data for Paretocharts because of their associated numeric indices.




• Free Format Comment – Enables entry of a text string, free form

comment that has no forced structure, but is useful for a general

comment that describes conditions. (Available only in pre-configuredcharts.)

• Subgroup Navigator (slider control at bottom) – Allows moving through

subgroups, without re-launching the Subgroup Details dialog.

Note: The subgroup that is selected for details display is displayed in the

chart with a magenta triangle.

SPC Parameters Dialog

To view the SPC Parameters dialog box, right-click on the currentlydisplayed SPC chart (for example, the Standard Deviation chart, Range [R]

chart, XBar chart, and so forth), and select SPC Parameters from thecontext menu.

Note: The SPC Parameters dialog box is not available when the plot is

displaying a histogram or a Pareto chart.The SPC Parameters dialog box allows modification to a number of

parameters that control the way SPC data is manipulated, formed into

subgroups, and the setting of alarm levels.

As shown in the figure below, many of the parameters in the SPC Parametersdialog box are enabled when an ad hoc chart is currently displayed, but

disabled when a pre-configured chart is displayed. For an ad hoc chart, itmay be desirable to use the SPC Parameters dialog box for making

adjustments. However, for a pre-configured chart, the disabled parameters(as displayed in the SPC Parameters dialog box) are stored in Real-Time

SPC records. Real-Time SPC records are edited by using the Aspen Real-Time SPC Configuration Utility (wizard) or InfoPlus.21 administrator tools

(see previous section, “Modifying or Deleting Real-Time SPC records”).

Figure 6-12 - Example SPC Parameters dialog boxes for ad hoc (left) and pre-configured (right) charts

The different areas of the SPC Parameters dialog box include these

parameters:

Subgroup area

• Subgroup Size – Specifies the number of samples in each subgroup.

• In limits – Specifies the number of subgroups used to calculate control

limits.




• Spec. Limits – Allows you to manually set Upper and Lower

specification limits.

CUSUM area

• Slack – Specifies the range about the target in which deviation from the

Target can be ignored.• Preload – Sets the initial value applied to the CUSUM the first time a

deviation occurs. This value gives the CUSUM a fast response todeviations. The default is 0.5.

• Alarm – Specifies the target band that the CUSUM should stay within.

• Display Slack Lines – Allows you to turn the display of the slack lines onthe chart on and off.

• Reset CUSUM to Preload Values – Forces the CUSUM to the Preloadvalues. This feature works only with pre-configured Real-Time SPC

records.

Note: The CUSUM is normally only reset to Preload values when a CUSUM

alarm is acknowledged. The Reset CUSUM to Preload Values parameterallows you to reset the CUSUM whenever you wish.

• MSSD Estimation On – Allows you to turn Mean Square Successive

Difference (MSSD) calculation of the standard deviation on and off. (Formore details about SPC formulas, see the Real-Time SPC for Process

Explorer Help.)

• Display Historical Limits – Enables the display of historical controllimits, which are plotted as dashed lines in contrasting colors, near the

solid lines representing current control limits. (If the historical limits are

the same as the current control limits, the dashed lines of historical limitswill not be visible.)

Note: Pre-configured Real-Time SPC records provide for storing historical

control limits whenever a new set of limits is either computed or manuallyset.

AutoCorrelation area

• Lag Periods – Sets the number of auto-correlation coefficients tocalculate.

• Alarm Level – Sets the auto-correlation coefficient alarm level.

EWMA area

• Lambda – Sets the EWMA smoothing constant.

• Alarm – Specifies the band on either side of the mean that designates the

alarm region.

• Use Fixed Limits – Allows you to turn fixed alarm limits on and off.

• Fixed High – Sets the upper fixed alarm limit.

• Fixed Low – Sets the lower fixed alarm limit.




SPC Control Limits Dialog

To view the SPC Control Limits dialog box, right-click on the currently

displayed SPC chart (for example, the Standard Deviation chart, Range [R]chart, XBar chart, and so forth), and select SPC Control Limits from the

context menu.

Note: The SPC Control Limits dialog box is not available from these charts:autocorrelation, Pareto, and histogram.

The SPC Control Limits dialog box shows the current and historical limits

specified in pre-configured Real-Time SPC records.

Note: Only current limits are displayed when viewing ad hoc charts, which donot store historical limits.

The following figure shows an example SPC Control Limits dialog box.

Figure 6-13 Example SPC Control Limits dialog box

When viewing a pre-configured Real-Time SPC record, you can change theHistorical Age parameter to see what limits were in effect in history.

Changing the Control Limits

There are two ways to change control limits in a pre-configured Real-Time

SPC record by using the SPC Control Limits dialog box:

• Use the Historical Age spinner box, and cycle through the history of

control limits, then enable Activate Historical Limits so that thecurrently displayed set of Historical Limits replaces the Current Limits (which will be automatically stored in history).

• In the Manual Limits area, enter values for UCL (upper control limit) and

LCL (lower control limit), then select (by checking) the Active checkbox.




SPC Alarms & Controls Dialog

To view the SPC Alarms & Controls dialog box, right-click on the currently

displayed SPC chart (for example, the Standard Deviation chart, Range [R]chart, XBar chart, and so forth), and select Active Alarms from the context

menu.

Note: The SPC Alarms & Controls dialog box is not available from thesecharts: autocorrelation, Pareto, and histogram.

The SPC Alarms & Controls dialog box shows:

• Which Real-Time SPC record is used to define the alarm rules.

• Which SPC alarms have occurred in a Real-Time SPC record or whichalarms would have occurred in an ad hoc chart.

• Which SPC alarms are currently active.

Alarm Rule Record – Displays the Real-Time SPC record in which the alarm

rules are defined.

Active SPC Alarms – Displays SPC alarms in the current data set andassociated alarm rules.

SPC Alarm Rules – Displays the active SPC alarm rules and allows you to

individually turn them on and off.

Alarm rules can be configured to implement standard rules or customized forparticular needs.

Alarm rule descriptions come from the associated alarm rule definition. Thealarm rule is defined by the user and may differ from the rules defined in your

alarm system.

See the later sections, “Alarms in Real-Time SPC for Process Explorer” and

“Common Alarm Rules,” for more information.

Ad Hoc to Q Dialog

To view the Ad Hoc to Q dialog box, right-click on the currently displayed adhoc SPC chart and select Convert Ad Hoc to Q from the context menu.

Note: The Ad Hoc to Q dialog box is not available from these charts:autocorrelation, Pareto, and histogram.

The Ad Hoc to Q dialog box allows you to create new Real-Time SPC recordsfrom ad hoc chart parameters.

From the currently displayed ad hoc chart, Ad Hoc to Q uses trend data,

subgroup parameters, and alarm rules. Then you specify the remainingparameters, listed and explained below:

SPC Variable Name – Create a name for the new SPC variable.

Note: Ad Hoc to Q generates a default name from the original ad hoc variable

name.

SPC Variable Type – Select one of the following SPC variable types:

• Xbar/R – Uses range to estimate variance within a subgroup.




• Xbar/s – Calculates standard deviation, a direct estimate of variance

within a subgroup.

• Xbar/R Enhanced – Uses range to estimate variance within a subgroup.Enhanced variables support EWMA fixed limits and MSSD calculation of

standard deviation. (See Note below.)

• Xbar/s Enhanced – Calculates standard deviation, a direct estimate ofvariance within a subgroup. Enhanced variables support EWMA fixed limits

and MSSD calculation of standard deviation. (See Note below.)

Note: Enhanced variable types require InfoPlus.21.

Limits Calculations – Select one of the following methods for defining the

initiation, timing, and frequency of limits calculation:

• Subgroup interval for calculations – Set the number of subgroupsbetween automatic recalculation of limits.

• Subgroups for initial calculations – Select the number of subgroups

required for the first limits calculation.

• Limits Update Method – Select how limits are recalculated. There are

three choices:o All Limits User-Specified – The user specifies limits.

o Calculate Once Using CIMQ_MEAN – Limits are calculated one time

after the Subgroups for initial calculations condition has been met.The mean and standard deviation computed to this point are used to

calculate limits.

o Recalculate Periodically – Limits are recalculated periodically, based

on the Subgroups interval for calculations and Subgroups forinitial calculations values.

Scheduling

•

Time – Displays the next time the Real-Time SPC record will becalculated.

• Interval – Allows you to set the time interval between calculations.

EWMA Limits

• Fixed Limits – Toggles EWMA fixed limits on or off.

• High – Allows you to manually enter a high EWMA fixed limit.

• Low – Allows you to manually enter a low EWMA fixed limit.

Note: EWMA fixed limits are available only in enhanced SPC variables. All

other variables will continue to use calculated limits.

Use MSSD Method for standard deviation estimate?

Allows you to choose between normal and MSSD standard deviation methodof calculation.

Note: The MSSD calculation option requires InfoPlus.21 and an enhanced

variable type.




Individuals Estimation Method

Allows you to choose how the range will be calculated when Subgroup Size is

set to one.

Individuals sigma method – Allows you to choose how the range is

calculated when Subgroup Size is one. There are three choices:

•

ESTIMATED SIGMA – The estimated value of sigma is stored in the Real-Time SPC record by the user. Use estimated sigma when minimal data is

available for a new SPC variable.

• ARTIFICIAL RANGE – The range is calculated using the differencebetween successive subgroups.

• MOVING AVG RANGE – The range is calculated as the average of the

difference between the subgroups within the Moving average aperture.

Moving average aperture – Allows you to select how many subgroups will

be used to calculate the range with the MOVING AVG RANGE estimationmethod.

HistoryAllows you to save additional history data in legacy databases. These historyitems are stored in InfoPlus.21 databases automatically.

For each of these parameters, enter some value that is greater than one, and

excess will be transferred to the history system.

Control Limits – Store control limits in history when the Limits UpdateMethod is set to Recalculate Periodically or when limits are changed through

the SPC Control Limits dialog. Enter the number of control limits to store.

Note: Historical limits are stored when limits calculations occur.

Subgroups – Store subgroups in history. Enter the number of subgroups tostore.

Raw Data – Store raw data in history when data is input directly into theReal-Time SPC record. Enter the number of raw data values to store.

Aspen Real-Time SPC AnalyzerConfiguration Utility (Wizard)

To run the Aspen Real-Time SPC Analyzer Configuration Utility (wizard), usethe Windows Start menu and select Aspen Manufacturing Suite | Aspen

InfoPlus.21 | Real-Time SPC Configuration.

Note: Avoid mistaking a similar selection found in the Windows Start menu:

Aspen Manufacturing Suite | Real-Time SPC Configuration. This

displays a command line, server side configuration tool used for enablingReal-Time SPC operations in the InfoPlus.21 database.

Aspen Real-Time SPC Analyzer Configuration Utility displays a ‘wizard’

sequence of seven (7) dialog boxes so that all of the parameters for defininga new Real-Time SPC record can be specified:




1 Server Selection – Select the server where the Real-Time SPC record will

be stored.

2 SPC Variable Identification – Name and describe the new Real-TimeSPC record.

Note: If you enter an SPC Variable Identification (name) that already

exists in the database, a dialog is displayed enabling you to either chooseanother name or update the existing Real-Time SPC record. If you choose

to update the existing record, all of the subsequent wizard dialogs will bepopulated with data from the existing record.

3 SPC Variable Type – Choose which type of Real-Time SPC record you

create.

4 SPC Input & Display Properties – Choose what data the Real-Time SPC

record processes and how it is displayed.

5 SPC Variable Control Properties – Select how calculations are

performed on the data.

6 SPC History Properties – Select additional data to store in History.

7 Summary and Commit – Review the parameters for the new Real-Time

SPC record and save it.

Note: For more detail, see the “Aspen Real-Time SPC Analyzer Configuration

Wizard” topics in the Real-Time SPC for Process Explorer Help, or click theHelp button in each dialog box of the wizard sequence to view a help topic

that explains the parameters that must be selected or completed. Also, thereare numerous tool tips within each dialog (displayed by hovering the mouse

cursor over an item of interest).

Histogram Parameters DialogTo view the Histogram Parameters dialog, right-click on the currently

displayed histogram and select Histogram Parameters from the contextmenu.

Note: The Histogram Parameters dialog box is only available when the plot

is displaying a histogram.

The Histogram Parameters dialog box allows you to change the calculation

and display properties for the histogram.

The following figure shows an example Histogram Parameters dialog box.




Figure 6-14 Example Histogram Parameters dialog box

The Histogram Parameters dialog box includes these parameters for

adjusting the calculation and display properties of the currently displayedhistogram:

Number of Bins – Enter the number of bins into which the data is to be

divided. The default value is determined by the number of samples in thepopulation.

Plot Maximum (Frequency) – Enter the maximum value of the vertical axis

scale.

Ppk start date/time – Select the starting date and time of the data used tocompute P p and P pk statistics (process performance and process performance

index). All points from the P pk start date/time to the present date/time will

be included, unless limited by a setting greater than zero (0) in Max. pointsto read for P pk statistic.

Note: The P p / P pk window defaults to the same time frame as the C p /C pk

statistics (process capability and process capability index). For this reason,

when the histogram is first displayed, the C p /C pk and P p / P pk statistics are the

same.

Max. points to read for P pk statistic – Enter a value to limit the number of

data points read from history for determining the P pk statistic. Enter a value

greater than zero (0) to prevent the possibility of a lengthy data retrievalfrom history, or enter a value of zero (0) to indicate no limit.

Show Curve – Select whether to show the Gaussian curve on the histogram

display.

Cell Boundaries – The Cell Boundaries set the scale of the horizontal axis.

• Maximum – Enter the maximum cell boundary.

• Minimum – Enter the minimum cell boundary.

Specification Limits – Manually enter the manufacturing specification limits.

• Upper – Enter the Upper Specification Limit (USL).

• Lower – Enter the Lower Specification Limit (LSL).




Important: Process capability indices cannot be calculated unless

specification limits are entered.

Pareto Parameters Dialog

To view the Pareto Parameters dialog, right-click on the currently displayedPareto chart and select Pareto Parameters from the context menu.

Note: The Pareto Parameters dialog box is only available when the plot is

displaying a Pareto chart.

The following figure shows an example Pareto Parameters dialog box.

Figure 6-15 Example Pareto Parameters dialog box

The Pareto Parameters dialog box includes these parameters for adjustingthe display properties of the currently displayed Pareto chart:

Starting category – If desired, enter the index number of the Pareto

category you want displayed as the beginning, most prevalent category,displayed as the first bar graph of the Pareto chart.

Categories in display – Enter a value to limit the number of bar graphs, or

columns displayed in the Pareto chart.

Alarms in Real-Time SPC forProcess Explorer

Viewing Alarms in a ChartThe shape and color of the point on the chart indicates active alarms on an

open SPC chart.

A blue square indicates a data point in a normal state.A red triangle indicates a data point in an alarm state.

An alarm is an action to alert the operator, engineer, or statistician that there

may be a change in process performance determined by control chartanalysis.

Real-Time SPC for Process Explorer applies statistical rules to data to

determine if a process is in an alarm condition.




Note: The alarm rules and descriptions displayed in the Active Alarms dialog

box come from the InfoPlus.21 database. If you are using a database other

than InfoPlus.21, then the alarm rules default to standard one, three, andseven-point statistical alarms.

Viewing Alarm DetailsTo see details about the active alarms for the currently displayed chart, right-

click on the plot and select Active Alarms from the context menu. The SPCAlarms & Control dialog box is displayed.

In the SPC Alarms & Control dialog box, a list of active alarms is displayed

in the upper Active SPC Alarms area. Also, a list of the pre-configured alarmrules is displayed in the lower SPC Alarm Rules area, each of which can be

enabled or disabled.

How Alarms are Generated, Enabled, and

DisabledReal-Time SPC for Process Explorer automatically generates real-time

statistical alarms as subgroups are created. The various subgroup values,means, ranges, CUSUMs, and so on, are validated against the alarms enabled

for the record being processed.

Once the required data for a completed subgroup is calculated, the new value

is compared against the control limits and active alarm rules to determine ifthe subgroup or set of subgroups violates any of the selected rules.

For any pre-defined variable or attribute data, a subset of the user-defined

alarms may be enabled. Active alarms for pre-defined variables are selectedat the pre-defined record.

For ad hoc SPC charts, alarm rules may be turned off using the SPC Alarms& Control dialog box. Alarms indicated on ad hoc charts represent violations

of locally configured alarm rules that would have occurred if Real-Time SPC

for Process Explorer had processed the data in accordance with pre-configured Real-Time SPC records.

To enable or disable the application of the individual alarm rules for the chartthat you are viewing, use the list of SPC Alarm Rules in the SPC Alarms &

Control dialog box. To turn off an alarm rule for the chart, clear the check

box to the left of the rule. To turn on an alarm rule, select the box so that it ischecked.

Note: Enabling or disabling an alarm rule only affects the display of the alarm

in the control chart, not the actual generation of alarms by the Real-Time SPCrecord.

How Alarm Rules are Configured

Alarm rules for both ad hoc and pre-configured SPC charts are configured

using Real-Time SPC records in the InfoPlus.21 database.




• Real-Time SPC records are defined using Ad Hoc to Q, Aspen Real-Time

SPC Analyzer Configuration Utility, the InfoPlus.21 Administrator, or the

InfoPlus.21 EngCon (Engineering Console) See the InfoPlus.21 Administrator Help.

For real-time statistical alarms to be displayed in Real-Time SPC for Process

Explorer, the alarm rules must have been configured in the Real-Time SPCrecord.

Common Alarm Rules

The most common alarm rules are:

• 1 MEAN HI – any subgroup mean above the Upper Control Limit (UCL).

• 1 MEAN LOW – any subgroup mean below the Lower Control Limit (LCL).

• 3 MEANS HI – any 3 consecutive subgroup means above 0.5 UCL.

• 3 MEANS LOW – any 3 consecutive subgroup means below 0.5 LCL.

• 7 MEANS HI – any 7 consecutive subgroup means above the mean.

•

7 MEANS LOW – any 7 consecutive subgroup means below the mean.• 1 STDDEV HI – any standard deviation above the Upper Control Limit

(UCL).

• 1 STDDEV LOW – any standard deviation below the Lower Control Limit

(LCL).

• 3 STDDEV HI – any 3 consecutive standard deviations above 0.5 UCL.

• 3 STDDEV LOW – any 3 consecutive standard deviations below 0.5 LCL.

• CUSUM HI – cumulative sum of deviations above target exceeds limit.

• CUSUM LOW – cumulative sum of deviations below target exceeds limit.

• EWMA HI – calculated Exponentially Weighted Moving Average (EWMA)value exceeds high limit.

•

EWMA LOW – calculated Exponentially Weighted Moving Average(EWMA) value exceeds low limit.

Note: The alarm system also permits the definition of trend alarms, whichindicate a specified number of subgroups moving in a single direction.

Maps for Real-Time SPC forProcess Explorer Data Access

to InfoPlus.21Real-Time SPC for Process Explorer uses the data access mechanism (DA forInfoPlus.21) to read and write the various database information required for

the control charts.

For data access to occur, each of the pre-defined Real-Time SPC record typeshas an associated map for subgroup data and a map for historical control

limits.




Note: It is necessary to have a different map for the historical control limits

because the map for the subgroup data only provides a reference to a single

history repeat area. Therefore, two areas are mapped: a subgroup data areaand a history repeat area. Generally, it is not necessary to modify these

maps.

Maps are made up with pairs of (1) an attribute name and (2) the field namewhere that attribute can be found.

Within the map, there is a fixed area and a repeat area, which have thefollowing characteristics:

• The fixed area of a map contains commonly used fields for normal data

access.

• The repeat area of a map is expandable and is used to point at field

names for virtually any other field in the database specific to theapplication. The repeat area is made up of pairs of fields, where the first is

the attribute name, and the second is the field name where that attribute

can be found.

In the repeat area, the attribute name is the name that Real-Time SPC for

Process Explorer will use when the database is queried for the value.

Example Maps for XBarR21

Below are example maps for the pre-defined Real-Time SPC record forXBarR21. The maps for the subgroup data and the historical control limits are

shown, both with fixed and repeat areas.

Notes:

• The example maps only show the “R” variable. There are minimal

differences between the “R” variable (variance based on range) and the “s” variable (variance based on standard deviation).

• Display of the historical limits became a standard feature of Real-TimeSPC for Process Explorer (formerly Aspen Q for Process Explorer) in

version 6. Consequently systems using version 6 require the maps forhistorical control limits. Any InfoPlus.21 database earlier than version 6

will need to include these map records for the comment and historical

limits enhancements to function properly.

Subgroup Data: Fixed Area

Attribute / Value Field Name

XBarR21Map NAME

SPC Testing MAP_Usage

InfoPlus21 MAP_Platform

Q_XBAR21Def MAP_DefinitionRecord

TRUE MAP_IsDefault

DESCRIPTION MAP_Description

MAP_Units





CUSUM Alarm 13 MAP_Attribute

Q_CUSUM_ALARM_LIMIT 13 MAP_FieldName

CUSUM Preload 14 MAP_Attribute

Q_CUSUM_PRELOAD 14 MAP_FieldName

CUSUM Slack 15 MAP_Attribute

Q_CUSUM_SLACK 15 MAP_FieldName

Subgroup Range/Sigma Value 16 MAP_Attribute

Q_RANGE 16 MAP_FieldName

Subgroup CUSUM High Value 17 MAP_Attribute

Q_CUSUM_HIGH 17 MAP_FieldName

Subgroup CUSUM Low Value 18 MAP_Attribute

Q_CUSUM_LOW 18 MAP_FieldName

MSSD Flag 19 MAP_Attribute

Q_MSSD 19 MAP_FieldName

EWMA Fixed Limits Flag 20 MAP_AttributeQ_EWMA_FIXED_LIMITS 20 MAP_FieldName

EWMA Fixed High Limit 21 MAP_Attribute

Q_EWMA_FIXED_HIGH 21 MAP_FieldName

EWMA Fixed Low Limit 22 MAP_Attribute

Q_EWMA_FIXED_LOW 22 MAP_FieldName

Reset Preload 23 MAP_Attribute

Q_RESET_CUSUM? 23 MAP_FieldName

Fixed Comment 24 MAP_Attribute

Q_FIXED_COMMENT 24 MAP_FieldName

Free Comment Time 25 MAP_Attribute

Q_FREE_COMM_TIME 25 MAP_FieldName

Use in Limits 26 MAP_Attribute

Q_USE_IN_LIM_CALCS ? 26 MAP_FieldName

Historical Control Limits: Fixed Area


XBarR21HstLimMap NAME

SPC Historical Limits MAP_Usage

InfoPlus21 MAP_Platform

Q_XBAR21Def MAP_DefinitionRecordFALSE MAP_IsDefault

DESCRIPTION MAP_Description

MAP_Units

Q_LSL MAP_Base

Q_USL MAP_Range

MAP_CurrentValue





MAP_CurrentTimeStamp

MAP_CurrentQuality

Q_LIMITS_IN_MEMORY MAP_HistoryArea

Q_HIS_UCL MAP_HistoryValueQ_HIS_LIMIT_TIME MAP_TimeStamp

MAP_Quality

MAP_Status

MAP_Type

PLANT AREA MAP_Area

MAP_T2Value

5 MAP_#Maps

Historical Control Limits: Repeat Area


Mean History 1 MAP_Attribute

Q_HIS_MEAN 1 MAP_FieldName

LCL History 2 MAP_Attribute

Q_HIS_LCL 2 MAP_FieldName

UCL R/s History 3 MAP_Attribute

Q_HIS_UCL_R 3 MAP_FieldName

Mean R/s History 4 MAP_Attribute

Q_HIS_MEAN_R 4 MAP_FieldName

LCL R/s History 5 MAP_Attribute

Q_HIS_LCL_R 5 MAP_FieldName



7 Glossary 73

7 Glossary

Ad Hoc Chart

A chart that displays process trends but cannot be used to control the

process. Ad hoc charts can be used to identify variables that may be suitablefor use in a pre-configured Real-Time SPC record.

Alarm

An action, determined by various control chart analyses, that alerts the

operator, engineer, or statistician that there may be a change in processperformance.

Assignable Cause

A factor contributing to the variation in quality that is economically feasible toidentify. Assignable causes must be identified and eliminated to attain

statistical control.

Autocorrelation Chart

The autocorrelation chart plots a set of correlation coefficients on a single

data set for several time-lag intervals. This helps you to see the consistency

and verify the independence of your data over time. You can also useautocorrelation charts to assess the performance of feedback controllers.

A correlation coefficient ranges from negative one (–1), the maximum degree

of inverse correlation, to positive one (+1), the maximum degree of positive

correlation.

Average

A value that represents the significance of a set of unequal values. An

average is determined by summing the values in a subgroup, then dividing bythe number of values in the subgroup.

XBar ( X ) is the average of the values within a subgroup.

XBar Bar ( X ) is the average of subgroup averages.

Bar

Found in a histogram. The height of a bar represents the count or number ofsamples per bin in the histogram.



74 7 Glossary

Bell-Shaped Curve

A curve that represents normal distribution of data around the mean. Same

as a Gaussian curve.

Bin

An interval in a histogram. Each bin in a histogram represents a value range

and contains some number of samples that fall into the interval or value

range for the bin. The value range for each bin is the range of the cellboundaries divided by the number of bins.

Central Line

The central line or lines on a control chart that represents the process

average of the items being plotted.

Common Cause

A source of variation that affects all the individual values of the processoutput being studied. In control chart analysis, a common cause appears as

part of the random process variation.

Control Chart

A trend chart that is used to control a process.

Control Limit

The calculated limit shown as a line or lines on a control chart and used as a

basis for judging the significance of the variation from subgroup to subgroup.Variation beyond a control limit is evidence that special causes are affecting

the process. Control limits are calculated from process data and are differentfrom engineering specifications.

C p (Process Capability)

A measure of the ability to produce product within the specification limits.Higher values of process capability indicate that a large proportion of the

product will be within the specification limits.

C p is the ratio of the range of the specifications to six times the estimate of

the process standard deviation. The higher the value of C p, the more capable

the process is.

For example, for a process that has its average value on target, a C p of 1.0

translates to a defect rate of just over one per thousand. Many industries

have recently set a quality goal of one defect per million. The C p value for this

level of quality is 1.6.

C pk (Process Capability Index)

A measure of the ability to produce product within the specification limits.Higher values of the process capability index, C pk, indicate that a large

proportion of the product will be within the specification limits.



7 Glossary 75

C pk is the ratio of the difference between the process average and the

specification limit that is closest to three times the estimate of the processstandard deviation.

CUSUM (Cumulative Summation)

The summation of the deviation from target of each of the subgroup values.

Data Table

A textual display of the values of a tag over a span of time.

EWMA (Exponentially Weighted Moving Average)

A statistic that applies a smoothing factor to subgroup data. This smoothingfactor may be adjusted to attach more or less importance to older subgroups.

The current value of the EWMA is a prediction of the next observation.

EWMA (Exponentially Weighted Moving Average)

Smoothing Factor

A weighting factor in the range of zero to one (0–1) given to older subgroup

values in the EWMA calculation. When the factor equals 1, an EWMA chartapproximates the X chart. When the weighting factor is close to 0, the EWMA

takes on the appearance of the CUSUM chart.

Gaussian Distribution

Refers to a common way that natural phenomena approximately arrangethemselves. True normal distribution is a mathematical abstraction, never

perfectly observed in nature. Same as Normal Distribution.

Histogram

A histogram is a graphical representation of the distribution of process data.

The width of each column in a histogram represents a value range. The heightof each column in a histogram represents the frequency, or number of

observations in each cell.

History

A series of process data records that are stored in a time-indexed database.

Lambda ( λ )

Determines the memory of the EWMA statistic. The rate of decay is

determined by lambda, which determines the amount of information used

from the historical data. Refers to the smoothing factor on the EWMA chart.

Legend

In Process Explorer, the scrollable display at the bottom of the plot area that

shows the tag name and other information for each Pen plotted on the



76 7 Glossary

display. For workspaces with more than one Plot, each Plot has its own

Legend.

Mean

The average of values in a group of measurements.

Median

The value that splits the process data in half. Half the measurements areabove the median and half the measurements are below the median.

Mode

The measurement of process data that occurs most frequently.

MSSD (Mean Square Successive Difference)

An alternative method for calculating standard deviation.

Nonconformity

A specific occurrence of a condition, which does not conform to specifications

or other inspection criteria. Requirements often include so-called "accepted

standards of good workmanship" as well as specifically stated limits.

Normal Distribution

Refers to a common way that natural phenomena approximately arrange

themselves. True normal distribution is a mathematical abstraction, never

perfectly observed in nature. Same as Gaussian distribution.

One-Sided CUSUM (Cumulative Summation)

The cumulative sum of deviation of subgroup values from the target value,which is sensitive to the sign of the deviation. A one-sided CUSUM value may

represent only the deviations above target or only the deviations belowtarget.

Population

The group for which an action may be taken, based on information derived

from the sampling or data.

Population MeanThe population mean is the average or mean of the population.

P p (Process Potential)

Process potential ( P p). A measure of the ability of the process to achieve a

certain level of consistent quality.



7 Glossary 77

P p is the ratio of the range of the specifications to six times the estimate of

the process standard deviation. The higher the value of P p, the more capable

the process is.

For example, for a process that has its average value on target, a P p of 1.0

translates to a defect rate of just over one per thousand. Many industrieshave recently set a quality goal of one defect per million. The P p value for this

level of quality is 1.6.

P p is calculated in the same way as C p but over a larger set of data.

P pk (Process Potential Index)

Process potential index ( P pk). A measure of the ability of the process to

achieve a certain level of consistent quality. Higher values of the process

capability index, P pk, indicate that a large proportion of the product will be

within the specification limits.

P pk is the ratio of the difference between the process average and the

specification limit that is closest to three times the estimate of the process

standard deviation. P pk is calculated in the same way as C pk but over a larger set of data.

Range ( R)

The difference between the highest and lowest values of process data. ARange is always a positive number.

RBar

The average of the subgroup ranges.

Real-Time SPC recordA special database record that generates statistical control data from processdata.

Real-Time SPC record Charts

A chart that displays process trends and is used to control the process. Real-

Time SPC record charts directly display information generated by a pre-configured Real-Time SPC record.

RTSA (Real-Time Statistical Alarming)

Alarms that are generated in real time by a Real-Time SPC record to indicatesthat a process is out of specification.

Sample

An element or subgroup of data upon which a single calculation can beperformed.



78 7 Glossary

Scooter

In Process Explorer, a scooter is a line (cursor) inserted into the plot that

provides a quick way to view the data values of a pen at a particular point intime.

Sigma (σ )Refers to standard deviation. A measure of the amount of deviation from themean or average.

Slack

One half (1/2) of the smallest shift in the mean value that is considered

important to detect quickly with the CUSUM test.

Smoothing Factor

Lambda ( λ ). Determines the memory of the EWMA statistic. The rate of decay

is determined by lambda, which determines the amount of information usedfrom the historical data. Refers to the smoothing factor on the EWMA chart.

Specification Limit

A constant, such as an engineering tolerance, that limits the maximum

amount of variation from a specification.

Standard Deviation

This is a measure of the amount of deviation from the mean or average.

Square root of the variance.

SPC (Statistical Process Control)

The use of statistical techniques such as control charts to analyze a process inorder to take appropriate actions to achieve and maintain a state of statistical

control and to improve the process capability.

SPC Variable

A single item of data in a Real-Time SPC record.

SQC (Statistical Quality Control)

The use of statistical techniques such as trend charts to analyze a process or

its outputs.

Subgroup

One or more events or measurements used to analyze the performance of a

process. Rational subgroups are chosen so that the variation representedwithin each subgroup is as small as feasible for the process (representing the

variation from common causes) and so that any changes in the processperformance (special causes) will appear as differences between subgroups.



7 Glossary 79

Tag

In Process Explorer, a record and the data associated with it at a particular

moment. Tags may be input (received from the process) or output (sent tothe process). They may be external or derived from an equation involving the

value of other tags. Tags may be analog or digital. Tags are sometimes called

points or data points.

Target

The mean value used in CUSUM calculations. If the user has supplied the

process mean, that value is used for the target. If the process mean is notsupplied, the calculated or estimated mean is used.

Timeline

A tool that controls the time frame of the data in the Plot. Includes all the

elements that control the time frame in which data is displayed. This includesthe global timeline, time slider, calendar, plot span, and the fixed time span.

Trend Chart

The graphical representation of data on the window.

Variance

Average of the squared deviations from the mean.

XBar

The mean. The average of values in a group of measurements.

XBar Bar

The process average. The average of the subgroup averages.

XBar Chart

A control chart based on variances from the subgroup average.



80 7 Glossary



Index 81

Index

active alarms, 18, 58, 64

ad hoc to Q dialog, 58ad hoc vs. pre-configured, 4, 37,

55, 57alarm factor (or level)

autocorrelation, 56CUSUM, 49, 56

EWMA, 48, 56

alarm rules for ad hocReal-Time SPC for Process

Explorer, 64alarm rules records, 15, 31, 58, 64

alarms for Real-Time SPC record,

58, 65alarms for subgroup, 54

artificial ranges method, 10, 27Aspen Process Explorer, 33

Aspen Real-Time SPC Analyzer

features list, 3installing, 13

overview, 3

Aspen Real-Time SPC for ProcessExplorer

task, TSK_CIMQ, 14AspenTech support, 2

AspenTech Support Center, 2

autocorrelation charts, 11, 50bins

histogram parameters, 39, 62number of, 39, 62

C data, 11CIMVIEW products, 33

comment records, 18, 54context menu, Real-Time SPC for

Process Explorer, 35

control chartsuses of, 8

control limitschange of, 28, 57

historical data, 31, 56, 57

number of subgroups used, 55SPC control limits dialog, 57

convert ad hoc to Q, 58Cp and Cpk, 40

creating new Real-Time SPCrecords

Real-Time SPC for Process

Explorer, 37, 58, 60customer support, 2

CUSUM

charts, 10, 30, 48pre-load, 30, 49, 56

values, historical, 24data tables

dialog in Real-Time SPC for

Process Explorer, 52database configuration, 15

database records

alarm rules, 15comments, 18

creating with Real-Time SPC forProcess Explorer, 37, 58, 60

deleting, 37fixed areas, 23

modifying with Real-Time SPC

for Process Explorer, 37, 61Pareto, 20

repeat areas, 23SPC variables, 23

documentation, 2e-bulletins, 2

enhanced variables, 59

equations, 38estimated sigma method, 10, 27

EWMA charts, 11, 30, 46fixed areas in Real-Time SPC data

records, 23, 66

fixed comment records, 19, 54



82 Index

formulas, 31, 38

free comment records, 19, 55

help (online), Real-Time SPC forProcess Explorer, 2, 31, 38

help (online),Real-Time SPC for

Process Explorer, 61

help desk, 2histograms

details, 40

parameters dialog, 61

Real-Time SPC for ProcessExplorer, 38

uses of, 7historical limits

configuring in ad hoc to Q dialog,60

enabling display of, 56in range chart, 43

in SPC control limits dialog, 57

in standard deviation chart, 41in XBar chart, 45

InfoPlus.21Aspen Real-Time SPC Analyzer

software relationship with, 13

maps for Real-Time SPC forProcess Explorer data access,

65, 66Real-Time SPC records in, 23

Real-Time SPC software

relationship with, 1records for alarm rules, 15

version 6 or earlier, 66installing Aspen Real-Time SPC

Analyzer, 13

lambda, smoothing factor, 30, 47,56

LCL (lower control limit), 57

legend, 36limits calculations control, 59

LPC (lower process capability), 39LSL (lower specification limit), 30,

39, 56, 62manuals, 2

maps for Real-Time SPC for

Process Explorer, InfoPlus.21,65

mean, 8measurements, multiple vs.

individual, 10, 27median, 8

mode, 8

modifying Real-Time SPC records,


moving average, moving rangemethod, 10, 27

MSSD (mean square successive

difference), 31, 56, 59new document, Real-Time SPC for

Process Explorer, 34newcimq21.rld, 14

normal distribution, 8NP data, 11

opening a chart display


outlier subgroups, 54

P data, 11Pareto charts

parameters dialog, 63


sample counts, 50uses of, 7

Pareto records, 20Pp and Ppk, 40, 62

pre-configured vs. ad hoc, 4, 37,55, 57

pre-load for CUSUM, 30, 49, 56

process capability (Cp) and index

(Cpk), 40Process Explorer, AspenTech, 33

process potential (Pp) and index(Ppk), 40

Q_XBAR21Def, 23, 31

Q_XBARCDef, 23Q_XBARCSDef, 23

Q_XBARDef, 23

Q_XBARS21Def, 23Q_XBARSDef, 23

Q_XR_ALARM_RULES, 15R charts, 9

range, 8range charts


Explorer, 42Real-Time SPC

data records, 13Real-Time SPC

data records, 4Real-Time SPC

data records, 15

Real-Time SPCdata records, 23



Index 83

Real-Time SPC (wizard), 60

Real-Time SPC for Process Explorer

ad hoc to Q dialog, 58autocorrelation charts, 50

common chart display features,

36

control limits dialog, 57creating new Real-Time SPC

records, 37, 58, 60

CUSUM charts, 48

data table dialog, 52displays, conversion to binary,

14EWMA charts, 46

histograms, 38, 61maps to InfoPlus.21 data access,

65modifying Real-Time SPC

records, 37, 61

new chart, 34online help, 2

overview, 33Pareto charts, 49

Pareto parameters, 63

range charts, 42Real-Time SPC Analyzer

Configuration Utility (wizard),60

SPC alarms and controls dialog,

58SPC parameters dialog, 55

standard deviation charts, 40subgroup details dialog, 53viewing charts, 34

XBar charts, 44repeat areas in Real-Time SPC data

records, 23, 66

right-click menu, Real-Time SPCfor Process Explorer, 35

S charts, 9sample counts, 50

scooters, 36, 39, 50, 52slack, 49, 56

smoothing factor (lambda), 30, 47,

56SPC

alarms and controls dialog, 58,64

concepts, 7control charts, 8

control limits dialog, 57

parameters in Real-Time SPC forProcess Explorer, 55

statistical process control, 7

SPC Parameters dialog, 55specification limits, 30, 39, 56

standard deviationin autocorrelation chart, 51

in CUSUM chart, 49

in EWMA chart, 47in histogram, 40

in range chart, 44in standard deviation chart, 42

in XBar chart, 45

use of, 8standard deviation charts


tips for, 42

subgroups, 8alarms in subgroup details, 54

data maps, 65

data storage control, 31details in Real-Time SPC for

Process Explorer, 53formation of, 28

in ad hoc charts, 46navigator slide control, 55

outlier, 54size of, 27, 42, 55

support, technical, 2

target, 49technical support, 2

timeline, 36

TSK_CIMQ, 14, 16U data, 12

UCL (upper control limit), 57UPC (upper process capability), 39

USL (upper specification limit), 30,39, 56, 62

variations and causes, 9

web site, technical support, 2wizard, Real-Time SPC Analyzer

Configuration Utility, 60XBar charts

R charts, 9, 23


Explorer, 44S charts, 9, 24

types of, 9validating against

autocorrelation, 52

aspenrealtimespcanalyzerv7 1 usr

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