Strategies for Designing and Implementating Effective Human Computer Interface for SCADA System

Ministry of Higher Education and Scientific Research

University of Technology

Computer Engineering and Information Technology Department

DESIGN AND IMPLEMENTATION OF

USER INTERFACE; STRATEGIES FOR

EFFECTIVE HUMAN COMPUTER

INTERFACE

A Thesis Submitted to the Department of

Computer Engineering and Information Technology

University of Technology

In Partial Fulfillment of the Requirements for the Degree of

Master of Science in

Software Engineering

Prepared By:

Muna Dhia Sheet Khattab

Supervised By:

Dr. Mohammed Najim Abdullah

March, 2007 Rabia I, 1428

صدق اهللا العظيم

)سورة العلق(

DEDICATED TO;

My sons

Ahmed and Mohammed

And more so to my

Father and Mother

But most to my husband

Kais

CERTIFICATION

I certify that this thesis entitled Design and Implementation of User

Interface; Strategies for Effective Human Computer Interface was

prepared under my linguistic supervision. Its language was amended to meet

the style of English language.

Signature

Name:

Date:

SUPERVISOR’S CERTIFICATION

I certify that the preparation of this thesis entitled Design and

Implementation of User Interface; Strategies for Effective Human

Computer Interface was made under my supervision by Muna Dhia Sheet

Khattab at the Department of Computer Engineering and Information

Technology in the University of Technology in partial fulfillment of

requirements for the degree of Master of Science in Software Engineering.

Signature

Dr. Mohammed Najim Abdullah

Supervisor

Date: / /2007

ACKNOWLEDGMENT

I am highly indebted to my supervisor Dr. Mohammed Najim

Abdullah for his supervision, guidance and encouragement through this

work.

Next, I would like to express my sincere thanks and gratitude to Prof.

Dr. Munther N. Baker for his assistance in conducting this work.

I also express my gratitude to Eng. Anas Younis who was very helpful

in his suggestions and support through the course of this work.

Finally, I would like to thanks Mr. Nazar AlQuraishi who has

facilitated my obtaining the necessary data for the work.

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LIST OF ABBREVIATIONS

ADO ActiveX Data Object

COM Component Object Model

CPM-GOMS Cognitive Perceptual Motor Goal Operators

Methods Selection

DB Database

DBMS Database Management System

DCS Distributed Control System

GOMS Goal Operators Methods Selections

GUI Graphical User Interface

HCI Human Computer Interface

HMI Human Machine Interface

IP Internet Protocol

IS Information Systems

LAN Local Area Network

LUCID Logical User- Centered Interaction Design

MDAC Microsoft Data Access Components

MFC Microsoft Foundation Classes

MMI Man Machine Interface

MS Microsoft

NCS National Communication System

NDC National Dispatch center

OAI Object Action Interface

ODBC Open Database Connectivity

OLE Object Linking and Embedding

OLE DB Object Linking and Embedded Database

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PC Personal Computer

PLC Programmable Logic Controller

PSN Public Switched Network

RAM Random Access Memory

RTU Remote Terminal Unit

SCADA Supervisory Control and Data Acquisition

SDLC System Development Life Cycle

SQL Structured Query Language

TAG Task Action Grammars

TIB Technical Information Bulletin

UHF Ultra High Frequency

UI User Interface

UIMS User Interface Management System

VHF Very High Frequency

WAN Wide Area Network

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ABSTRACT

The study of the strategies for Effective Human Computer Interaction (HCI) is

a powerful primer on how - and why - some products satisfy customers while others

only frustrate them. As computer use became more widespread, the number of

researchers specialized in studying the interaction between people and computers

increased. These researchers deal with the physical, psychological and theoretical

aspects of such interaction.

Many products that require users to interact with them to carry out their tasks

have not necessarily been designed with the users in mind. Typically, they have been

engineered as systems to perform set functions. The aim of this thesis is to redress this

concern by bringing usability into the design process. In essence, it is about

developing interactive products that are easy, effective, and enjoyable to use –from

the users’ perspective.

This thesis shows that the success of any user-interface development depends

on three pillars; guidelines documents and processes, users-interface software tools,

and expert review and usability testing. These three pillars help user-interface

architects to turn good ideas into successful systems. Experience has shown that each

pillar can produce an order-of- magnitude speedup in the process and can facilitate the

creation of excellent systems.

This methodology for effective and interactive human computer interface

design was applied to Iraqi Power Generation Stations, Supervisory Control and Data

Acquisition (SCADA) System and was tested by using real database taken from

AlQurashi Bureau. SEMATIC Window Control Center (WinCC), version 6,

developed by Siemens AG was used to design the SCADA and HCI modules.

Evaluation methods were applied to the developed product such as cognitive

walkthrough, competitive usability testing, and questionnaire for user interaction

satisfaction (QUIS) and finally quality test of the developed product was conducted.

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CONTENTS

Title Page

Chapter One

General Introduction

1.1 Introduction 2

1.2 Definition of HCI: 3

1.3 Advantages and applications of HCI 4

1.4 The Importance of HCI 5

1.5 Professionals involved in HCI 6

1.6 SCADA Systems 6

1.7 Literature survey 8

1.7.1 Work related to HCI 8

1.7.2 Work related to SCADA system 10

1.7.3 Work related to usability 12

1.8 Work Objectives 12

1.9 Thesis Outline 12

Chapter Two

HCI Guidelines, Principles and Theories

2.1 Introduction 15

2.2 Guidelines 16

2.2.1 Navigation of the interface 17

2.2.2 Organization of the display 17

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2.2.3 Recommendations for guidelines documents 18

2.3 Principles 19

2.3.1 Determine users’ skill levels 20

2.3.2 Identify the tasks 21

2.3.3 Choose an interaction styles 22

2.3.4 Use the eight golden rules of interface design 24

2.3.5 Prevent Errors 26

2.4 Theories 26

2.5 Object-Action Interface Model 27

2.5.1 Task hierarchies of objects and actions 27

2.5.2 Interface hierarchies of objects and actions 28

2.5.3 The disappearance of syntax 29

2.6 LUCID Development Methodology 29

Chapter Three

Software Tools, Expert Reviews and Usability Testing

3.1 Introduction 34

3.2 Software-Engineering Tools 34

3.3 Criteria of Finding the Right Design Tool 36

3.4 SIMATIC WinCC HMI 38

3.4.1 WinCC Advanced Features 39

3.4.2 WinCC Traditional HMI Tasks 40

3.5 SCADA Screens 41

3.5.1 Schematic Pages 41

3.5.2 Database Pages 42

3.5.3 Alarm/Event Pages 42

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3.5.4 Report Pages 43

3.5.5 Operator Pages 43

3.6 Database Management System 43

3.6.1 SQL Server 44

3.6.2 ActiveX Data Object 44

3.7 Evaluating Interface Designs 45

3.7.1 Expert Reviews 45

3.7.2 Expert-Reviews Report 48

3.8 Usability Definition 49 3.8.1 Usability Testing and Laboratories 49 3.8.2 Limitations of Usability Testing 50

3.9 Survey and Questionnaire 50 3.9.1 Questionnaire for User Interaction Satisfaction (QUIS) 51

3.10 Acceptance Tests 51

3.11 Evaluation during Active Use 52

Chapter Four

Implementation of HCI for SCADA System

4.1 Introduction 54

4.2 Case Study: The Electrical Power Generation System 54

4.3 Communication System 57

4.4 Master station 59

4.5 Electrical Power Generation Station (field data interface devices) 59

4.5.1 Power station specifications 60

4.6 Defining SCADA Modules 62

4.6.1 Graphic Designers 63

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4.6.2 Plant Program 65

4.6.3 Report Designer Module 65

4.6.4 Trends Module 66

4.6.5 Alarm Generation Module 67

4.6.6 Achieving Module 69

4.6.7 Data Base Modules 69

4.6.7.1 System database 70

4.6.7.2 Archive Database 70

4.6.7.3 Tag Database 70

4.6.8 Application Module 71

4.6.9 HMI Module 71

4.6.9.1 HMI Main Page 71

4.6.9.2 Navigation Page 72

4.6.9.3 HMI Schematic Pages 74

4.6.9.4 Database Pages 76

4.6.9.5 Alarm/ Event Pages 76

4.6.9.6 HMI Trending Pages 77

4.6.9.7 HMI Report Pages 77

4.6.9.8 HMI System Pages 79

4.6.9.9 HMI Operators Pages 79

Chapter Five

HCI and SCADA System Test

5.1 Introduction 82

5.2 Requirements for the Installation of WinCC 83

5.2.1 Hardware Requirements for the Installation of WinCC 83

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5.2.2 Software Requirements for the Installation 84

5.3 Expert Reviews 84

5.3.1 Cognitive walkthrough technique 84

5.4 Usability Testing 85

5.5 Questionnaire for User Interaction Satisfaction (QUIS) 85

5.6 Running the SCADA Product 91

5.7 Developed Product Quality Test 92

Chapter Six

Conclusions and Suggestions for Future Work

6.1 Conclusion 95

6.2 Suggestions for Future Work 97

References 99

Appendix A

SCADA System Functions A-1

Appendix B

Walkthrough and Heuristic Evaluation B-1

Appendix C

Questionnaire for User Interaction Satisfaction C-1

CHAPTER ONE

GENERAL INTRODUCTION

Chapter One; GENERAL INTRODUCTION

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CHAPTER ONE

GENERAL INTRODUCTION

1.1 Introduction Old computing was about what computers could do; the new

computing is about what users can do [22]. Successful technologies are

those that are in harmony with users’ needs. Researchers and designers

could claim success, but user expectations are higher, applications are more

demanding, and the variety of platforms has grown. In addition to desk top

computers designers must now accommodate web-based services and

mobile devices. At the same time, some innovators provoke us with virtual

and augmented realities, whereas others alluring scenarios for ubiquitous

computing, embedded devices, and tangible user interfaces [3]. Human-

Computer Interaction (HCI) is the study of how people design, implement,

use interactive computer systems, and how computers affect individuals,

organizations, and society. This encompasses not only ease of use but also

new interaction techniques for supporting user tasks, providing better access

to information, and creating more powerful forms of communication. It

involves input and output devices, interaction techniques, how information is

presented and requested, how the computer's actions are controlled and

monitored and all forms of help, documentation, and training. It also

includes tools used to design, build, test, and evaluate user interfaces and the

processes that developers follow when creating interfaces.


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Users expect highly effective and easy-to-learn interfaces, and

developers now realize the crucial role the interface plays. Surveys show that

over 50% of the design and programming effort on projects are devoted to

the user interface portion [40, 52]. Interface design is a major part of HCI,

because there are also well-known catastrophes that have resulted from not

paying enough attention to the human-computer interface [3].

Figure 1.1: The Nature of Human Computer Interaction

1.2 Definition of HCI: There is currently no agreed upon definition of the range of topics

which form the area of human-computer interaction. Yet it is needed to

characterize the field to get the right definition, therefore from a computer


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science perspective, since it’s focus is on interaction and specifically on

interaction between one or more humans and one or more computational

machines, it can be defined as;

“Human-computer interaction is a discipline concerned with the design,

evaluation and implementation of interactive computing systems for

human use and with the study of major phenomena surrounding them.”

[39].

1.3 Advantages and Applications of HCI Human Computer Interaction helps to produce business success

stories and produce intense computation for organizations. Routine

processes and decision support are also affected by HCI for individual user

level as well as communities for globalization and family use. Below is a

brief of such effects [3];

• Organizations

- Success Stories: Microsoft, Linux, Amazon.com, Google.

- Compétition : Netscape vs. Internet Explorer.

- Copyright Infringement Suits: Apple vs. Microsoft (Windows) and

Napster vs. The music industry.

- Mergers: AOL and Time Warner.

- Corporate Takeovers: IBM’s seizure of Lotus.

- Privacy and Security issues: identification theft, medical information,

viruses, spam, pornography, national security.

• Individual User Level

- Routine processes: tax return preparation.

- Decision support: a doctor’s diagnosis and treatment.


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- Education and training: encyclopedias, drill- and practice exercises,

simulations

- Leisure: music and sports information.

• Communities

- Business use: financial planning, publishing applications.

- Industries and professions: web resources for journals, and career

opportunities.

- Family use: entertainment and communication.

- Globalization: language and culture.

1.4 The Importance of HCI Human-Computer Interaction studies a human and a machine in

communication; it draws from supporting knowledge on both the machine

and the human side. On the machine side, techniques in computer graphics,

operating systems, programming languages, and development environments

are relevant. On the human side, communication theory, graphic and

industrial design disciplines, linguistics, social sciences, cognitive

psychology, and human performance are relevant. As well as engineering

and design methods are also relevant. Therefore, the answer to why Human-

Computer Interaction is;

- 40-60% of today’s software consists of user interfaces [22].

- Such interfaces support high interactivity with the user, much end-user

programming

-User interactivity is only going to get more complex: 3D graphics and

virtual reality, augmented reality activities….

- Many usability problems are due to a bad interface design.


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- Users sabotage systems they don’t understand.

- Users make more errors when dealing with systems that are difficult to

use.

- A well-designed user interface can reduce coding costs, interface

problems, life-threatening errors; can also lead to increase sales

…more...

1.5 Professionals Involved in HCI The interdisciplinary design science of Human- Computer Interaction

(HCI) combines knowledge and methods associated with professionals

including:

- Psychologists (including experimental, educational, and industrial

psychologists).

- Computer scientists.

- Instructional and graphic designers.

- Technical writers.

- Human factors and ergonomics experts.

- Anthropologists and sociologists.

1.6 SCADA Systems SCADA is an acronym for Supervisory Control and Data Acquisition.

SCADA systems are used to monitor and control a plant or equipment in

industries such as; energy, oil and gas refining, telecommunications, and

transportation. These systems encompass the transfer of data between a

central host computer and a number of Remote Terminal Units (RTUs)

and/or Programmable Logic Controllers (PLCs), and the central host and the


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operator terminals. A SCADA system gathers information, transfers the

information back to a central site, then alerts the home station that a trip has

occurred, carrying out necessary analysis and control, such as determining if

the trip is critical, and displaying the information in a logical and organized

fashion. These systems consist of:

- One or more field data interface devices, usually RTUs, or PLCs, which

is interfaced to field sensing devices and local control switchboxes and

valve actuators.

- A communications system is used to transfer data between field data

interface devices and control units and the computers in the SCADA

central host. The system can be based on radio, telephone, cable,

satellite, etc., or any combination of these.

- A central host computer server or servers (sometimes called a SCADA

Center, master station, or Master Terminal Unit (MTU).

- A collection of standard and/or custom software [sometimes called

Human Machine Interface (HMI) software or Man Machine Interface

(MMI) software] systems are used to provide the SCADA central host

and operator terminal application, support the communications system,

and monitor and control remotely located field data interface devices.

The SCADA traditional communication systems have made use of the

Public Switched Network (PSN) for monitoring purposes. Today many

systems are monitored using the infrastructure of the corporate Local Area

Network (LAN)/Wide Area Network (WAN). Wireless technologies are

now being widely deployed for purposes of monitoring. Figure 1.2 shows a

typical SCADA system [43].


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1.2: Typical SCADA System

1.7 Literature Survey There are many research papers and articles related to this subject.

The following are some of these classified according to the subject of an

interest.

1.7.1 Work Related to HCI

Waleed Khalid, 1997, developed user interface management system

(UIMS) named Stanple. It is supported by rapid prototype and incremental

development through simple, fast, and easy to implement HCI [52]. Stanple

has the following features;

- Running under Windows 3.1

- The use of configuration program.

- Full monitoring and controlling of the system.


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- Supports schematic and Alarm/Event pages only.

Hadeel Abdul-Ammeer, 2000, developed user interface management

system (UIMS) named HCI Studio [20]. Many concepts of HCI design, like

interface styles, principles to support interface usability, and interface

independence where are studied in her thesis. The studio has the following

features;

- Running under Windows 95, 98, and NT.

- Full graphical features.

- Password protection.

- Arabic HCI.

- On-Line help.

- Flexible and attractive HCI.

- Supporting Schematic and Alarm/Event pages only.

Afrah Thamir Ali, 2005, presented many concepts of high quality

software engineering like modularity, high cohesion and low coupling

studied which are used to enhance HCI quality [1]. The enhanced HCI has

the following features;

- HCI is divided into three separate modules.

- Full visualization of the process.

- Containing all SCADA necessary pages.

- Reusability, Productivity and user satisfaction are achieved.

- Running under windows 2000 operating system.

- Password protection.

Ping Zhang, Jane Carey, Dov Te’eni and Marilyn Tremaine, 2005,

stated that incorporating a human computer (HCI) perspective into the

system’s developed life cycle (SDLC) is necessary for information systems


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(IS) success and, in turn, for the success of businesses to achieve human-

centered IS development approach [39].

1.7.2 Work Related to SCADA System

Suyeong Kim, 1997, developed a prescriptive model of human

intervention based on given probabilistic descriptions of the performance of

a decision aid and the performance of an operator, and cost functions for

consequences of each decision [43]. Work features are:

- The model provides a conceptual basis for a new human-computer

interface to give operators more refined advice on alternative actions

than is given in the current interface.

- The new interfaces guarantee correct human interventions, which results

in the improvement of overall performance.

- The new interface reduces the operator’s decision making time.

Michael P.Wardin, 2004, highlighted security and stability due to

recent failures of critical infrastructure of SCADA systems. The first step

towards achieving these concepts is developing an abstract generic

framework for defining and understanding SCADA systems [32]. The work

features are;

- Matrix approach is provided to understand the system’s features,

functions and capabilities, and how components in the system relate and

interface with each other.

- The variety of open communication protocols have been defined and

described.


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- Two small SCADA systems, using industry standard components and

simulating real word applications, were designed and constructed to

provide context for applying the matrix approach.

Mitsuya Kato, Katsufumi Watahiki, Tatsuyuki Suzuki, 2004,

continued the evolution of networking and PC technologies, enabled better

integration of control center systems and drove down operating costs [31].

Work features:

- Employing low-cost-high performance PC servers.

- Preserving the excellent reliability and processing capabilities of

Hitachi’s existing supervisory control technologies.

- The new comprehensive system combines an integrated control center

system based on PC servers running Linux and substation controller

connected to WANs using IP technology.

National Communications system (NCS) developed technical

information Bulletin (TIB) 04-1 on supervisory control and data acquisition

(SCADA) systems [36]. An overview of SCADA is provided, and security

concerns are addressed and examined. Work features:

- Identifying developing and coordinating proposed standards which either

contributes to the interoperability of functionality of similar

telecommunication systems or to the achievement of the compatible and

efficient interface between computer and telecommunications systems.

- Considerable amount of effort is expended in initiating and pursuing

joint standards development through efforts from appropriate technical

committees of the International Organization for Standardization, the

International Telecommunication Union and Telecommunication

Standardization Sector.


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1.7.3 Work Related to Usability

Xavier Ferre’, Natalia Juristo, Helmut Windl and Larry Constantine,

2001, showed the relationship between usability and the users interface, and

how the usability process follows a design-evaluate-redesign cycle was

discussed [51]. Some management issues mentioned.

Ben Sheiderman, 2003, promoted the idea of multi-layer interface

designs that enable first-time and novice users to begin with a limited set of

features at layer1 [3]. They can remain at layer1, then move up to higher

layers when needed or when they have time to learn future features.

1.8 Work Objectives The objectives of this project are;

- Studying the strategies for the design and implementation of an effective

HCI for SCADA system by:

- Presenting a broad survey of how to develop high-quality user interfaces

for interactive systems.

- Paying greater attention usability issues and promoting further scientific

study of human computer interaction.

1.9 Thesis Outline This chapter provides an introduction to the meaning of Human

Computer Interface and the Supervisory Control and Data Acquisition

systems as well as the main previous studies in this field. Also, chapter two

defines the necessary guidelines, principles and object /action model of HCI.


13

Chapter three illustrates the second and third pillars of successful user

interface development (software tools) especially SIMATIC HMI developed

by SIEMENS and (expert review and usability testing), chapter four

describes the development of HCI modules and SCADA modules in terms of

software structure, main functions, algorithms, and graphical appearance.

Chapter five illustrates the tests’ results of the developed HCI modules and

SCADA modules. Finally, chapter six presents conclusions and suggestions

for future work.

CHAPTER TWO

HCI GUIDELINES, PRINCIPLES,

AND THEORIES

Chapter TwO; HCI GUIDELINES, PRINCIPLES, AND THEORIES

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CHAPTER TWO

HCI GUIDELINES, PRINCIPLES AND THEORIES

2.1 Introduction The study of the strategies for the design of an effective human computer

interface is a difficult challenge. It requires a careful study of guidelines,

principles, theories and how they can be integrated into the design process.

Designs should be based on careful observation of current users, refined by

thoughtful analysis of task frequencies and sequences, and validated through early

usability and through acceptance tests [4]. The variety of design situations

precludes a comprehensive strategy. However, these strategies began with the

organizational design that gave appropriate emphasis to support usability [5].

Figure 2.1: The three pillars of successful user-interface development.

Successful User Interfaces

Academic Research

Theories And Models

Algorithms And Prototypes

Controlled Experiments

Guidelines Documents And Process

User Interface Software

Tools

Expert Reviews And

Usability Testing


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There are three pillars of successful users-interface development; guidelines

documents and processes, users-interface software tools, and expert review and

usability testing (Figure2.1) [4]. These three pillars will be described in this

chapter which helps user-interface architects to turn good ideas into successful

systems. Experience has shown that each pillar can produce an order-of-

magnitude speedup in the process and can facilitate the creation of excellent

systems.

Also this chapter shows that the logical User-Centered Interaction Design

(LUCID) methodology which, is a good framework for scheduling.

2.2 Guidelines From the earliest days, interface designers have tried to write down

guidelines to record their insight and guide the efforts of future designers.

Figure 2.2: Guidelines documents and processes

“A guidelines document helps to develop a shared language and then promote

consistency among multiple designers in terminology, appearance, and action

Navigation of the interface

− Standardize task sequences. − Ensure that embedded links are descriptive − Use unique and descriptive headings − Develop pages that will print properly − Use thumbnail images to preview larger images

Organization of the display

− Consistency of data display − Efficient information assimilation by the user − Minimal memory load on the user − Compatibility of data display with data entry − Flexibility for user control of data display

Recommended guidelines documents

− Terminology(object and actions), − Icons, buttons graphics, and line thickness − Menu selection, form fill-in, and dialog box formats − Wording of prompts, feedback, and error messages. − Data entry and display formats for items and lists − Strategies for adapting to small and large displays − Response times for a variety of tasks − Action sequences − Shortcuts and programmed function keys − Error handling and recovery procedures − Online help and tutorials − Training and reference materials

Guidelines


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sequences. It records best practices derived from practical experience or

empirical studies with appropriate examples” [4].

The following sections show selected guidelines depending on action which

can be adopted by agreement among people concerned with interface design.

2.2.1 Navigation of the Interface

Since navigation can be difficult for many users, providing clear rules is

helpful. This sample of guidelines comes from the National Cancer Institute [25].

- Standardize task sequences. Allow users to perform tasks in the same sequences

and manner across similar conditions.

- Ensure that embedded links are descriptive. When using embedded links, the

link text should accurately describe the link’s destination.

- Use unique and descriptive headings. Use headings that are unique from one

another and conceptually related to the content they describe.

- Develop pages that will print properly. If users are likely to print one or more

pages, develop pages with widths that print properly.

- Use thumbnail images to preview larger images. When viewing full-size images

is not critical, first provide a thumbnail of the image.

2.2.2 Organization the Display

Display design is a large topic with many special cases. Smith and Mosier

(1986) offered five high-level goals as part of their guidelines for data display [11]:

- Consistency of data display. During the design process, the terminology,

abbreviation, formats, colors, capitalization, and so on should all be standardized.

- Efficient information assimilation by the user. The format should be familiar to

the operator and should be related to the tasks required to be performed with the

data.


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- Minimal memory load on the user. Users should not be required to remember

information from one screen for use on another screen. Tasks should be arranged

such that completion occurs with few actions, minimize the chance of forgetting

to perform a step. Label and common formats should be provided for novice or

intermittent users.

- Compatibility of data display with data entry. The format of displayed

information should be linked clearly to the format of the data entry. Where

possible and appropriate, the output fields should also act as editable input fields.

- Flexibility for user control of data display. Users should be able to obtain the

information from the display in the form most convenient for the task on which

they are working.

2.2.3 Recommendations for Guidelines Documents

The creation of a guidelines document at the beginning of an implementation

project should focus attention on the interface design and provides an opportunity

for discussion of controversial issues. [4]

Guidelines documents must be living texts that are adapted to change in

needs and refined through experience [14].

Each project has different needs, but guidelines should be considered for:

Terminology(object and actions),abbreviations, and capitalization

Icons, buttons graphics, and line thickness

Menu selection, form fill-in, and dialog box formats

Wording of prompts, feedback, and error messages.

Data entry and display formats for items and lists

Strategies to adapt small and large displays

Response times for a variety of tasks

Action sequences; Direct manipulation click, drag, drop, and gestures


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Shortcuts and programmed function keys

Error handling and recovery procedures

Online help and tutorials

Training and reference materials

2.3 Principles While guidelines are narrowly focused, principles tend to be more

fundamental, widely applicable, and enduring. However, they also tend to need

more clarification.

Figure 2.3: Fundamental Principles

− Direct manipulation − Menu selection − Form fillin − Command language − Natural language

− Strive for consistency − Cater universal usability − Design dialogs to yield closure − Error prevention − Permit easy reversal of actions − Support internal locus of control − Reduce short-term memory load

− Novice or first time users − Knowledgeable intermittent users −Expert frequent users

− Task frequency − Task sequence

− Correct actions − Complete sequences

Principles

Interaction styles

Eight golden rules

Users’ skill levels

Identify the tasks

Prevent Errors


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There are differences in users’ background knowledge, training in the use of

the system, frequency of use, and goals as well as in the impact of a user error.

Since no single design could satisfy all these users and situations, successful

designers must characterize their users and the situations in which their products

will be used as precisely and completely as possible [50].

2.3.1 Determine Users’ Skill Levels

All designs should begin with an understanding of the intended users,

including population profiles that reflect age, gender, physical and cognitive

abilities, education, cultural or ethnic background, training, motivation, goals, and

personality.[22]

The process of getting to know the users is never - ending because there is so

much to know and because the users keep changing. Every step in understanding

the users and in recognizing them as individuals with outlooks different from the

designer’s own is likely to be a step closer to a successful design.

A generic separation into novice or first- time, knowledgeable intermittent

and expert frequent users might lead to these differing design goals [14]:

• Novice or first time users. To overcome this problem, via instructions, dialog

boxes, and online help, are a series challenge to the designer of the interface. The

number of actions should also be small, so that novice and first - time users can

carry out simple tasks successful and thus reduce anxiety, build confidence, and

gain positive reinforcement. Error messages should be provided when users make

mistakes. Carefully designed manuals, video demonstrations, and task oriented

online tutorials may be effective.

• Knowledgeable intermittent users. Consistent sequences of actions, meaningful

messages, and guides to frequent patterns of usage will help knowledgeable

intermittent users to rediscover how to perform their tasks properly. These


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features will also help novices and some experts, but the major beneficiaries are

knowledgeable intermittent users. Protection from danger is necessary to support

relaxed exploration of features or usage of partially forgotten action sequences.

These users will benefit from context-dependent help to fill in missing pieces of

task or interface knowledge .Well- organized reference manuals are also useful.

• Expert frequent users. Expert power users are thoroughly familiar with task and

interface concepts and seek to get their work done quickly. They demand rapid

response times, brief and non-distracting feedback, and the shortcuts to carry out

actions with just a few keystrokes or selections. Strings of commands, shortcuts

through menus, abbreviations, and other accelerators are requirements.

2.3.2 Identify the Tasks

After carefully drawing the user profile, the developers must identify the

tasks to be carried out. Every designer would agree that the set of tasks must be

determined before design can proceed, but too often the task analysis is done

informally or implicitly [22].

Task analysis helps designers to understand task frequencies and sequences

and make the tough decisions about what tasks to support.

High level task actions can be decomposed into multiple middle-level task

actions, which can be further refined into atomic actions that users execute with

single command, menu selection, and so on. Choosing the most appropriate set of

atomic actions is a difficult task. If the atomic actions are too small, the users will

become frustrated by the large number of actions necessary to accomplish a

higher-level task. If the atomic actions are too large and elaborate, the users will

need many such actions with special options, or they will not be able to get exactly

what they want from the system [3].


22

2.3.3 Choose an Interaction Styles

When the task analysis is completed and the task objects and actions have

been identified, the designer can choose one of the following interaction styles;

direct manipulation, menu selection, form fill in, command language, and natural

language. Direct manipulation interaction style was chosen for the developed

project of this thesis [4].

• Direct manipulation. An interaction style in which objects are represented and

manipulated in a manner similar to the real word [14]. By pointing at visual

representations of objects and actions, users can carry out tasks rapidly and can

observe the results immediately. This type of interaction is appealing to novices,

is easy to remember for intermittent users, and with careful design can be rapid

for frequent users.

Advantages Disadvantages - Visually present task concepts - May be hard to program - Allows easy learning - May require graphics display and

pointing devices - Allows easy retention - Allows errors to be avoided - Encourages exploration - Affords high subjective satisfaction

• Menu selection. In menu-selection systems, users read a list of items, select the

one most appropriate to their task, and observe the effect. If the terminology and

meaning of the items are understandable and distinct, users can accomplish their

tasks with little learning or memorization and just a few actions. This interaction

style is appropriate for novice and intermittent users and can be appealing to

frequent users if the display and selection mechanisms are rapid.


23

Advantages Disadvantages - Shortens learning - Presents danger of many menus - Reduces keystrokes - May slow frequent users - Structures decision making - Consumes screen space - Permits use of dialog-management tools

- Requires rapid display rate

- Allows easy support of error handling

- Affords high subjective satisfaction

• Form fill-in. When data entry is required, menu selection alone usually becomes

cumbersome, and form fill-in (also called fill in the blanks) is appropriate. Users

see a display of related fields, move a curser among the fields, and enter data

where desired. With the form fill-in interaction style, users must understand the

field labels, know the permissible values and data-entry method, and be capable

of responding to error messages. Since knowledge of the keyboard, labels, and

permissible fields is required, some training may be necessary. This interaction

style is most appropriate for knowledgeable intermittent users or frequent users.

Advantages Disadvantages - Simplifies data entry - Consumes screen space - Requires modest training - Gives convenient assistance - Permits use of from-management tools

• Command language. For frequent users, command languages provide a strong

feeling of being in control. Users learn the syntax and can often express complex

possibilities rapidly, without having to read distracting prompts. However, error

rates are typically high, training is necessary, and retention may be poor. Error

messages and online assistance are hard to provide because of the diversity of


24

possibilities and the complexity of mapping from tasks to interface concepts and

syntax.

Advantages Disadvantages - Is flexible - Has poor error handling - Appeals to “power “users - Requires substantial training and

memorization - Support user initiative - Allows convenient creation of user-defined macro

• Natural language. Natural –language interaction effectiveness and advantages

are limited, mainly because of habitability issues. Natural language support has

success in text searching, text generation, extraction, and some instructional

systems [22].

Advantages Disadvantages - Relieves burden of learning syntax

- Requires clarification dialog

- May not show context - May require more keystrokes - Is unpredictable

2.3.4 Use the Eight Golden Rules of Interface Design

The eight principles, called Golden Rules are applicable to most interactive

systems. These principles as listed below derived from experience and refined over

two decades and have been well received as a useful guide to students and

designers [4].

- Strive for consistency. Following this rule can be tricky because there are many

forms of consistency. Consistent sequences of actions should be required in

similar situations; identical terminology should be used in prompts, menus, and


25

help screens; and consistent color, layout, capitalization, fonts, and so on should

be employed throughout.

- Cater for universal usability. Recognize the needs of diverse users. Novice-

expert differences, age ranges, disabilities, and technology diversity each

enriches the spectrum of requirements that guide design.

- Offer informative feedback. For every user action, there should be system

feedback. Visual presentation of the objects of interest provides a convenient

environment for showing changes explicitly.

- Design dialogs to yield closure. Sequences of actions should be organized into

groups with a beginning, middle, and end. The informative feedback at the

completion of a group of actions shows the user their activity has completed

successfully.

- Error prevention. Design the system so that users cannot make serious errors. If

the user makes an error, the interface should detect the error and offer a simple

recovery. Incorrect actions should leave the system state unchanged and give the

possibility to restoring the state.

- Permit easy reversal of actions. Actions should be reversible. This feature

relieves from anxiety, since the user knows that errors can be undone, thus

encouraging exploration of unfamiliar options.

- Support internal locus of control. Experienced users strongly desire the sense

that they are in charge of the interface and the interface responds to their actions.

Surprising system actions, tedious sequences of data entries, inability or

difficulty in obtaining necessary information, and inability to produce the action

desired all build anxiety and dissatisfaction.

- Reduce short-term memory load. A famous study suggests that humans can store

only 7 (plus or minus 2) pieces of information in their short term memory.


26

Designers can reduce short term memory load by keeping display simple,

reducing window-motion frequency and sufficient training and on line help [3].

2.3.5 Prevent Errors

One way to reduce the loss in productivity due to errors is to improve the

error messages provided by the interface. Better error messages can raise success

rates in repairing the errors, lowering future error rates, and increasing subjective

satisfaction. Superior error messages are more specific, positive in tone, and

constructive (telling the user what to do, rather than merely reporting the problem).

A more effective approach is to prevent the errors from occurring; this could

be done by two techniques correct actions and complete sequences [4]. Correct

action techniques can be applied by graying out in appropriate actions or allow

selection rather than freestyle typing and offer automatic completion while

complete sequences offer a sequence of steps as a single action.

2.4 Theories A theory, taxonomy or a model is an abstraction of reality; it goes beyond

the specifics of guidelines and builds on the breadth of principles. A good theory

should be understandable; produce similar conclusions for all how use it, and help

to solve specific practical problems.

Some theories are descriptive and explanatory; these theories are helpful to

observe behavior, describe activity, conceive of designs, compare high-level

concepts of two designs, and training. Other theories are predictive [22]; these

theories enable designers to compare proposed designs for execution time or error

rates.


27

A motor-task performance is a way to group theories; these theories are

helpful to predict key stroke or point times. Other theories are perceptual or

cognitive subtasks theories these theories predicting readings times for free text,

lists, or formatted displays one.

A variety of reliable and broadly applicable theories are beginning to emerge

for user interface (levels of analysis theories, stages-of-action models, GOMS and

the keystroke level model, consistency through grammars, widget level theories,

context of use theories) [46].

2.5 Object-Action Interface Model The OAI model is a descriptive and explanatory model that focuses on task

and interface objects and actions. Because the syntactic details are minimal, users

who know the task-domain objects and actions can learn the interface relatively

easily. The OAI model also reflects in the higher level of design with which most

designers deal when they use the widgets in user interface building tools. The

standard widgets have familiar and simple syntax (click, double click, drag, or

drop) and simple forms of feedback (highlighting, scrolling, or movement), leaving

designers free to focus on how these widgets create a business-oriented solution.

The OAI model is in harmony with the common software-engineering

method of object-oriented design [14].

2.5.1 Task Hierarchies of Objects and Actions

The primary way people deal with large and complex problems is to

decompose them into several smaller problems, in a hierarchical manner, until each

sub problem is manageable.


28

Tasks include hierarchies of objects and actions at high and low levels.

Hierarchies are comprehensible and useful. Most users accept a separation of their

tasks into high – and low-level objects and actions as shown in Figure 2.4 [4].

Figure 2.4; Task and interface concepts, separated into hierarchies of objects and

actions.

2.5.2 Interface Hierarchies of Objects and Actions

Once there is agreement on the task objects and actions and their

decomposition, the designer can create the metaphoric representations of the

interface objects and actions. Interface objects do not have weight or thickness;

they are pixels that can be moved or copied in ways that represent real-world task

objects with feedback to guide users.

The final step is that designer must make the interface actions visible to

users, so that users can decompose their plans into a series of intermediate actions,

such as opening a dialog box, all the way down to a series of detailed keystrokes

and clicks.

Objects Actions Objects Actions

atoms steps pixels clicks

universe intention metaphor plan

Task Interface


29

2.5.3 The Disappearance of Syntax

In the early days of computers, users had to maintain a profusion of device-

dependent details in their human memories, minimizing them is the goal of most

interface designers. Modern direct-manipulation styles support the process of

presenting users with screens filled with familiar objects and actions. Modern user-

interface building tools facilitate the design process by making standard widgets

easily available. Innovative designers may recognize opportunities for novel

widgets that provide a closer match between the screen representation and the

user’s workplace.

2.6 LUCID Development Methodology Successful developers work carefully to understand the business needs and

refine their skills in eliciting accurate requirements from non-technical business

managers.

However, many software development projects fail to achieve their goals.

Some estimates of the failure rate put it as high as 60%. Much of this problem can

be traced to poor communication between developers and the users [4].

In addition, business managers may lack the technical knowledge to

understand proposals made by the developers, dialog is necessary to reduce

confusions about the organizational implications of design decisions.

The Logical User-Centered Interactive Design (LUCID) methodology

identifies six stages to facilitate effective collaboration among teams that includes

both business and technical participants. These stages are listed in Table 2.1 [4].


30

Stage Description

Envision - Align the agendas of all stakeholders, balancing the needs to meet business objectives, manage technical constraints and support user’s needs for a highly usable product.

- Develop a clear, shared product vision among the stockholders. - Identify and deal with potential problems that could impair the

development team’s ability to collaborate effectively. - Begin the design process at a concept sketch level.

Discovery - Develop a clear understanding of the characteristics of each distinct segment of the product’s users.

- Understand the tasks users perform, the information they need, the terminology they use, their priorities and their mental models.

- Analyze the data gathered and create the product’s user requirements.

Design

Foundation

- Develop and validate the basic conceptual design of the product. - Develop a visual look for the product. - Present the completed design as a key screen prototype.

Design

Detail

- Complete a style guide containing both the graphic design and UI policy decisions.

- Flesh out the high- level design into a complete specification. - Conduct usability evaluation of critical screens or work flows. - Create detailed layouts for each screen and detailed specifications for each element of each screen.

Build - Answer questions and support developers during coding, redesigning screens if needed.

- Conduct usability evaluation of critical screens, if necessary. - Support the build process through review and late-stage change

management. Release - Develop a rollout plan to support the new product.

- Conduct usability evaluation of the “out of the box” or installation experience.

- Measure user satisfaction.

Table 2.1; Logical User-Centered Interaction design Methodology (from Cognetics

Cooperation, Princeton Junction, NJ).


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As a management strategy, LUCID focuses on user’s needs and

requirements and highlights the role of usability engineering in software

development by focusing on activities, deliverables, and reviews. At each of the

LUCID stages there are specified deliverables and timely feedback through

reviews, for components such as:

- Product definition: high concept for managers and marketers

- Business case: pricing, expected revenues, return on investment, competition

- Resources: duration, effort levels, team members, back up plans.

- Physical environment: ergonomic design, physical installation, communication

lines.

- Technical environment: hardware and software for development and integration.

- Users: multiple communities for interviews, user testing, and marketing.

- Functionality: services provided to users

- Prototype: early paper prototypes, key screens, running prototypes.

- Usability: set measurable goals, conduct tests, refine interface and goals.

- Design guidelines: modify existing guidelines, implement review process.

-Content Material: identify and acquire copy righted text, audio, and video.

- Documentation, training and help: specify, develop, and test paper, video, and

online versions.

The success of the LUCID framework comes from its validation and

refinement in multiple projects. The templates and techniques it provides help

design team structure their activities and deliverables. While LUCID is designed to

promote an orderly process, with iterations within a stage and predictable progress

between stages, the framework will need to be adapted to the realities of specific

projects and organizations. And while the concept of flow from stage to stage is a

useful structure for organizing user-centric design activities, some projects may


32

require the design team to back up and redo earlier stages if elements of the

product concept change dramatically [3,39].

CHAPTER THREE

SOFTWARE TOOLS, EXPERT

REVIEWS AND USABILITY

TESTING

Chapter Three; SOFTWARE TOOLS, EXPERT REVIEWS AND USABILITY TESTING

34

CHAPTER THREE

SOFTWARE TOOLS, EXPERT REVIEWS AND

USABILITY TESTING

3.1 Introduction The demands of modern life require user-interface architects to build

reliable, standard, safe, inexpensive, effective, and widely acceptable user interface

on a predictable schedule. Building and user-interface architects must have simple

and quick methods of sketching to give their clients a way to identify needs and

preferences [8]. They also need precise methods for working out the details with

clients, for coordinating with specialized colleagues, and for telling the

craftspeople what to do[4].

This chapter begins with the software-engineering tools. SIMATIC WinCC

HMI is selected as a software tool. Second the standard SCADA screens or pages

are presented. Then Data Base-Management System is discussed. Finally, a variety

of expert review methods, usability tests, surveys, and acceptance tests are

presented.

3.2 Software-Engineering Tools Software tools are increasingly graphical in their user interfaces, enabling

designers and programmers to build interfaces, rapidly by dragging components

and linking functions together. User interfaces building tools have matured rapidly

in the past few years and have radically changed the nature of software

development [36]. Productivity gains of 50 to 500% about previous methods have


35

been documented for many standards graphical user interfaces (GUIs)[4]. But,

even as the power tools for established styles improve and gain acceptance, the

need remains for programmers to handcraft novel interface styles.

Experienced programmers sometimes build user interfaces with general-

purpose programming languages such as Java, C#, or C++, but this approach is

giving way to using facilities that are specially tuned to user-interface development

and web access [36]. Choosing among them is sometimes a complex and confusing

task, due to the lack of uniform terminology used to describe the tools and their

features.

There are a large number of tools available for building user interfaces.

Table 3.1 lists the four software layers that can be used to build a user interface and

their associated interactive tools [4].

Software Layers Visual Tools Examples 4. Application Model-Based Building Tools Microsoft Access, Sybase

power Designer 3. Application Framework / Specialized Language

Conceptual Building Tools Macromedia Director, Tcl/Tk, Microsoft MFC

2. GUI Toolkit Interface Builder Eclipse, Borland J Builder, Microsoft Visual Studio

1. Windowing System Resources Editor Microsoft Win32/GDI+ Apple Quartz

Table 3.1: The four software layers available to build a user interface, their related

visual tools, and examples of popular tools at each level.

The higher software level tools, application layer tools, are interface

generators, and sometimes called user-interface management systems or model-

based building tools. Most if not all of an application can be built quickly using

these visual tools. However, these tools are currently available only for a small

class of applications [49].


36

Layer three tools include specialized languages or application frameworks.

These are software architectures specially designed for building graphical user

interface (GUIs). Compared to layer four tools, they provide almost no support for

nongraphical part of application. At this layer, a key distinction is how extensively

the software-engineering tool uses convenient visual programming, a relatively

simple scripting language (event or object oriented), or a more powerful general-

purpose programming language [48].

The terminology for GUI toolkits, layer two, varies depending on the

vendor. Popular terms for these toolkits include Rapid Prototype, Rapid

Application Developer, User Interface Builder, and User Interface Development

Environment. This layer provides software libraries and widgets as building blocks

but requires extensive programming to connect these components to each other and

to the non-GUI part of application [4].

The layer one windowing system tools require extensive programming by

experienced software engineers and offer little support from interactive tools [4].

3.3 Criteria of Finding the Right Design Tool The advantages of specialized user interface software tools for designers and

software engineers are large, and the promises of improved tools required that

designers and programmers stay informed of and make fresh choices for each

project. Finding the right tool is a tradeoff between six main criteria [4]:

• Part of the application is built using the tools. Some tools only support

building the presentation part of the application; others also help with low-

level interaction, and some support general programming mechanisms usable

in other parts of the application as well.

• Learning time. The time required to learn the tools varies.

• Building time. The time required to build a user interface using the tool varies.


37

• Methodology imposed or advised. Some tools strongly impose a methodology

for building the application, such as building the visual part first and

connecting it to the remainder of the application afterwards, whereas other

tools are more flexible.

• Communication with other subsystems. Applications frequently uses

databases, files located on the web, or other resources that, when supported by

the building tool, simplify the development.

• Extensibility and modularity. Applications evolve, and new applications may

want to reuse parts of existing applications. Supporting the evolution and

reuse of software remains a challenge. Level four tools and application

framework inherently promote good software organization, but the others

usually lead to poor extensibility and modularity.

Tool price is an important criteria, because it is usually negligible compared to

the cost of good designers and engineers. Furthermore, there is a growing trend to

distribute free tools suitable for building standard GUIs. Tables 3.2 summarize the

six criteria applied to the software layers [4].

Regardless of the tools used to design the user interface, designing for good

usability has important implications for the quality and complexity of software

development. Separating the user interface from the remainder of the application

has been quite successful and is now standard practice in interactive system

development. This separation makes it easier to make modifications to the user

interface without changing the internals and to maintain multiple views of

application data and facilitates cross-platform development, which makes it easier

to generate interfaces for standard platform families (Windows, Macintosh, and

UNIX) [16].


38

Layer

Part of the application built

Learning time

Building time

Methodology imposed or advised

Communication with other subsystems

Extensibility and modularity

4 All for a specific

Long Short Specification first, then visual, then programming (if required)

Very good for the specific domain of the tool

Very good

3 Presentation, interaction

Short (days)

Short Visual first Depends on the tool

Languages: Bad Frameworks: Good

2 Presentation, interaction

Long (weeks)

Long Visual first with tools, none otherwise

Good Medium\ good

1 All Very long (months)

Very long

None Very good Very bad

Table 3.2: Comparison between six features of design tools (horizontal) depending

on the software layer (vertical)

3.4 SIMATIC WinCC HMI SIMATIC WinCC HMI is a user interface management tool developed at

SIEMENS AG, 2000. It offers complete operating, control and monitoring

functionalities in Windows and XP for all sectors-from simple single user systems

up to distributed multiple station systems with redundant servers and cross-site

solutions with Web clients [44]. It also used to visualize the process and develop

the graphic user interface for the operator.

• WinCC allows the operator to observe the process. The process is displayed

graphically on the screen. The display is updated each time a status in the

process changes.

• WinCC allows the operator to control the process by predefining set points

from the graphic user interface [44].


39

• An alarm will automatically signal in the event of a critical process status. If a

predefined limit value is exceeded, a message will appear on the screen.

• Process values can either be printed or electronically archived. This facilitates

the documentation of the process and allows subsequent access to past

production data [44].

3.4.1 WinCC Advanced Features

WinCC uses ANSI C, which gives flexibility to perform simple and complex

tasks. C code can be generated by a wizard or written manually, it is implemented

in the graphics designer or on both object properties and events [44].

Visual Basic Script 6.3 (VBS) is fully integrated as a primary scripting

language in WinCC complete with debugging and easy to use object model. VBS

is implemented on both object properties and event in the graphics designer, as

well as having its own Global Scripts editor for project functions and actions. Also,

VBS can be used for traditional HMI tasks or to create more complex scripts such

as database access (ADO) or Excel worksheet generation [44].

Visual Basic for Application (VBA) has been fully integrated into WinCC’s

Graphics Designer as an engineering tool for configuration. VBA can be used to

automate respective engineering tasks, such as generating objects, tags, scripts,

alarms, and screens [44]. With VBA, custom forms and wizards can be created to

perform almost any task. However, the Graphical Designer can even customized

by adding customized menus. WinCC has been built on SQL server 2000 to

provide a powerful engine for Alarm, Tag Logging, and Recipe Archives [44].

Indirect addressing is a WinCC another feature that allows dynamic change

the tag assigned to a particular object while in runtime. On the other hand WinCC

Tag Prefix feature combines Structure Tags and Picture Window object to provide

an efficient engineering tool for equipment display popups or control screens. In


40

runtime, the combination of the structure tag name and the member name on the

object will provide the full I/O name for the object [44].

3.4.2 WinCC Traditional HMI Tasks

WinCC encompasses traditional HMI tasks and many time-saving features

as well. It is allowed to develop quickly and easy to maintain the applications.

WinCC supports the following HMI tasks [44]:

- Graphics: An active X container with thousands of library Symbols and Smart

Objects, VBA, On-line Changes, Panning, Zooming, Layering, Tool Tips

and other features provided with faster development times with more

intuitive interface [44].

- Alarming: Wizard configuration, Alarm Sorting, Alarm Enabling / Disabling and

individual operator comments provide a comprehensive Alarm

Management System. Multiple alarm levels on a single tag provide

simpler alarm development [44].

- Trending: Wizard configuration and independent scaling provide the WinCC user

with a full featured historical and real time trending utility. WinCC’s

trending support exporting data to formats like CSV that make the

information readable by off-line tools such as Microsoft Excel [44].

- Security: WinCC supports levels of security. Operator access to specific screens

or objects on screen can be prohibited. Individual actions such as recipe

download can be password protected as well. When using internet

Browser to view the application, firewall software is supported [44].

- OPC: WinCC can act as an OPC Client and an OPC Server. As an OPC Client,

WinCC can perform HMI tasks for hundreds of third-party control

devices. As an OPC Server, WinCC can provide tag information

upstream to various MES applications.


41

- Drivers: WinCC supports native channel drivers for the most popular PLC’s.

- Reports: A built in Report Designer supplies templates for creating shift reports,

production reports, alarm reports and others.

- Cross-Reference: WinCC provides a cross-reference utility for quickly searching

and replacing tags during development. The cross-reference utility

includes a built-in project documenter for keeping records on entire

application[44].

- Multi Languages: WinCC supports multiple languages during runtime and

development. Runtime support for any window-based language fonts

enables true Global language capabilities [44].

3.5 SCADA Screens SCADA HCI must be capable of displaying system information in two

formats Tabular and graphical. These two formats are broken into pages (or

screens) in an easy way to explain and understood manner. These pages include

schematic, database, alarm/event, report, and operator pages as described below.

3.5.1 Schematic Pages Schematic Pages give the operator a graphical model of the plant. They

comprise graphical symbols that can be linked to an element to be monitored and controlled [1]. The real-time measurements of the element are displayed next to their graphical symbol. Standard symbols are used in these pages

The state of the point is not written in longhand but is shown as visual effects like color change, shape change, symbol change, and/or flashing. It is of course impossible to display all real-time values of the system on schematic pages, only the most important ones are displayed there [38]. Also it is not possible to address all values that may affect the point state, so even though the point state is known, the cause of putting the point in such a state is unknown.


42

3.5.2 Database Pages

The same information contained in the schematic pages can be translated into tabular format in database pages. Database pages are so called since the HCI builds the page entirely from system database. System database contains all elements of the system, hence elements that are not displayed in schematic pages can be found in database pages. Moreover, all information related to an element is displayed in these pages [20].

The status of the point is shown through changing the text that mentions that state. Colors and flashing are used also to enhance state visualization.

The database pages do not help the operator to relate points to system configuration, but it does help him to find detailed information about the system. 3.5.3 Alarm/Event Pages

A SCADA system must be able to detect, display, and log system alarms and events. Alarms identify system failures while events identify system changes. The change can be caused by a control operation made by the operators to the plant or an actual state change that occurs in the plant.

Alarm/Event pages display all alarms and events that occur in the system in a tabular format. Every time the system generates an alarm (or event) a message will be added at the bottom of the Table. This message contains useful information about the alarm (or event) like the location of the alarm, the date and time of alarm occurrence, and the type of event that caused the alarm [1]. Colors, flashing, and audible alerts are all used to notify the operators of alarm occurrence.

Alarms and events must be recorded so that operator can review them in the future. This will help the operator to determine which device fails repeatedly, what the most popular alarms are, and what system part should be maintained. Through using Historical pages (of alarms and events) the operator can display all alarms and events that occurred during a certain period of time (usually one day) within a configurable time interval (1 month, 2 months …).


43

3.5.4 Report Pages As the Alarm/Event pages have their own archive facility and display

information upon request, the SCADA system provides the same facility to analog readings also. Report pages are where the operator can display the analog reading through certain period of time and within a configurable interval. Report pages can be displayed in two different ways [23]: - Report Tables; Report Tables display analog readings versus time in a tabular format. - Trends; Trends display analog readings versus time in a graphical format and via a trending chart. 3.5.5 Operator Pages

Operator Pages contain information related to the operators not to the SCADA system or to the plant. These pages include: - Operator Existence Pages; Operator Existence Pages contain information

about which operator is responsible for monitoring the system and at which time. Only operator’s supervisors can edit the contents of these pages.

- Operator Note Pages; Operator Note Pages contain operator’s notes about the plant and any other useful notes.

3.6 Database Management System

A Data Base-Management System (DBMS) is a collection of interrelated

data and set of programs to access those data. The collection of data, usually

referred to as the database, contains information relevant to an enterprise. The

primary goal of a DBMS is to provide a way to store and retrieve database

information that is both convenient and efficient.

Database systems are designed to manage large bodies of information.

Management of data involves both defining structures for storage of information

and providing mechanisms for the manipulation of information. In addition, the

database system must insure the safety for information stored, despite system


44

crashes or attempts at unauthorized access. If data are to be shared among several

users, the system must be avoiding possible anomalous results. Any user interface

deals with some kind of database. It is important to expose custom and legacy data

in a standard and more manageable way.

3.6.1 SQL Server

The SQL Server 2000 relational database engine is a modern, highly

scalable, and reliable engine for storing data. The database engine stores data in

tables. Each table represents some object of interest to the plant. Each table has

columns that represent an attribute of the object modeled by the table and rows that

represent a single occurrence of the type of object modeled by the table [45].

Applications can submit Structured Query Language (SQL) statements to the

database engine, which returns the results to the application in the form of a tabular

result set. The specific dialect of SQL supported by SQL Server is called Transact-

SQL.

3.6.2 ActiveX Data Object

ActiveX Data Object (ADO) is the latest in a long series of Microsoft Data

Access Component (MDAC), and it effectively supersedes the old Data Access

Object (DAO) and Remote Data Object (RDO). ActiveX Data Object is

application level interface with a consistent design across many programming

environments. It offers access to Jet data, traditional remote data sources, and new

data sources such as e-mail and file directory systems. ActiveX Data Object is the

recommended programming interface to develop applications that acts as Object

Linking and Embedded Data Base (OLEDB) consumers. Through ADO it is easy

to code but is still slower than OLEDB [1].


45

3.7 Evaluating Interface Designs Evaluation is a general term for determination of the significance, worth,

condition, or value of something of interests by careful appraisal and study [14].

Evaluation is basically ongoing process. Figure 3.1 depicts the central role of

evaluation during assistance development.

Figure 3.1: Evaluation as the center of system development.

The range of evaluation plans might be from an ambitious two-year test with

multiple phases for life critical projects to a three-day test with six users for small

projects. The range of costs might be from 20% of a project down to 5% [14].

3.7.1 Expert Reviews

A natural starting point for evaluating new or revised interfaces is to ask

colleagues or customers for their feedback. Such informal demos with tests

subjects can provide some useful feedback, but more formal expert reviews have

proven to be far more effective [39].

Task analysis/ Function analysis

Evaluation

Prototyping

Requirements Specification

Implementation

Conceptual Design

Visual Design


46

These methods depend on having experts (whose expertise may be in the

application or user-interface domains) available on staff or as consultants. Expert

reviews can then be conducted on short notice and rapidly.

Expert reviews can occur early or late in the design phase. The outcome can

be a formal report with problems identified or recommendations for changes. The

reviewers note possible problems for discussions with the designers but solutions

generally should be left to the designers to produce [4]. Expert reviews usually

take from half a day to one week, although a lengthy training period may be

required to explain the task domain or operational procedures. Different experts

tend to find different problems in an interface, so 3-5 expert reviewers can be

highly productive [4]. There are a variety of expert-review methods from which to

choose: Heuristic evaluation, Guidelines reviews, Consistency inspection,

Cognitive walkthrough, Formal usability inspection.

In this thesis a comparison between these methods has been done which is

shown in Table 3.3 and according to the features which is discussed in the table, a

decision was made to use the cognitive walkthrough evaluation method. The

following is a brief discussion of this method;

− Cognitive walkthrough. The experts simulate users walking through the

interface to carry out typical tasks. High-frequency tasks are a starting point,

but rare critical tasks, such as error recovery, also should be walked through.

Some form of simulating the day in the life of the user should be part of the

expert- review process. Cognitive walkthroughs were developed for inter-

faces that can be learned by exploratory browsing [53], but they are useful

even for interfaces that require substantial training.


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Life Cycle Stage

System Status

Environ. of Evaluation

Real Users Participation

User Tasks Used

Main Advantage

Main Disadvantage

Heuristic evaluation

Any stage; early ones benefit most

Any status (mock-up prototype, final product)

Any None None Finds individual problems; can address expert user issues

Does not involve real users and thus may not find problems related to real uses in real context; dose not link to user’s tasks

Guideline preview


Any status Any None None Finds individual problems

Does not involve real users; does not link to user’s tasks

Cognitive walk-through


Any status Any None Yes, need to identify tasks first

Less expensive Does not involve real users; limited to expert’s review

Consistency inspection

Any stage Any status Any None Yes, need to identify tasks first

Direct link to user tasks; structured with fewer steps to go through

Does not involve real users; limited to the tasks identified

Survey Any stage Any status Any Yes, a lot Yes or no Finds subjective reactions; easy to conduct and compare

Questions need to be well designed; need large sample

Interview Task analysis Mock-up prototype

Any Yes None Flexible, in-depth probing

Time-consuming; hard to analyzed and compare

Lab experiment Design, implement, or use

Prototype, final product

Lab Yes Yes, most time artificially designed to mimic real tasks

Provides fact-based measurements; results easy to compare

Requires facility, setup, and expertise

Field study with observation and monitoring

Design, implement, or use

Prototype, final product

Real work setting

Yes None Easy applicable; reveal user’s real tasks; can high light difficulties in real use

Observation may effect user behavior

Table 3.3; Comparison between evaluation methods


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An expert might try the walkthrough privately and explore the system, but

there also should be a group meeting with designers, users or managers, to

conduct the walkthrough and provoke discussions. Extensions to cover

website navigation incorporate richer descriptions of users and their goals

plus linguistic analysis program to estimate the similarity of link labels and

destinations [10].

3.7.2 Expert-Reviews Report

An expert review report should be comprehensive, rather than making

comments about specific features, or presenting a random collection of suggested

improvements by [4]:

− Guidelines documents might be used to structure the report, then comment on

novice, intermittent, and expert features and review consistency across all

displays.

− Theory or model, such as object-action interface model (described in section

2.5) might be used to organize the report.

− Recommendations must be ranked by importance and expected effort level so

the organizations are more likely to implement them (or at least the high-

payoff, low-cost ones).

− Experts reviewer should also include required small fixes such as spelling

mistakes, poorly aligned data-entry fields, or inconsistent button placements.

− A final category includes less vital fixes and novel features that can be

addressed in the next version of the interface.

− Experts reviewer may also used software tools to speed their analyses,

especially with large interfaces. These tools usually provide specific

instructions for improvements.


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3.8 Usability Definition International Standard Organization (ISO) defines usability as “The extent to

which the product can be used by specified users to achieve specified goals with

effectiveness, efficiency, and satisfaction in a specified context of use” [8], where

product is taken to mean a computerized system with given functionality.

3.8.1 Usability Testing and Laboratories

At each design stage, the interface can be refined iteratively and the

improved version can be tested. It is important to fix quickly even small flaws,

such as spelling errors or inconsistent layout, since they influence user

expectations [51]. Usability testing produced dramatic cost savings thus the

movement towards usability testing stimulate the construction of usability

laboratories. A typical modest usability lab would have two 3 by 3 meter areas, one

for the participants to do their work and another, separated by a half-silvered

mirror, for the testers and observers [22]. Participants should be chosen to

represent the intended user communities. Many variants forms of usability testing

have been tried: Paper mockups, Discount usability testing, Competitive usability

testing, Universal usability testing, Field tests and portable labs, Remote usability

testing, Can- you- break- this test.

In this thesis the decision was made to choose competitive usability testing

form since this testing approach compares a new interface to previous versions or

similar products from competitors. This approach is close to controlled

experimental study, and staff must be careful to construct parallel sets of tasks and

to counterbalance the order of presentation of the interfaces. Within-subjects

designs seem the most powerful, because participant can make comparisons


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between the competing interfaces fewer participants are needed, although each is

needed for a longer time period [4].

3.8.2 Limitations of Usability Testing

Usability testing does have at least two series limitations. It emphasizes first-

time usage since usability tests are usually only one to three hours long, it is

difficult to ascertain how performance will be after a week or a month of regular

usage [14]. Also, some believe that realistic test environments are necessary to

evaluate information appliances, and ambient technologies.

3.9 Survey and Questionnaire

Surveys are a well-established technique for collecting demographic data

and users’ opinions. Efforts and skill are needed to insure that questions are clearly

worded and the data collected can be analyzed efficiently [4]. This technique is

familiar, inexpensive and generally acceptable companion for usability tests and

expert reviews. The keys to successful survey are clear goals in advance and

development of focused items that help to attain those goals.

Surveys start by asking for basic demographic information, such as age,

gender, and past experience. This background information is useful in finding out

the range within the sample group.

Survey goals can be tied to the components of the OAI model of interface

design (Section 2.5). That is, users can be asked for their subjective impressions

about specific aspects of the interface, such as the representation of:

• Task domain objects and actions.

• Interface domain metaphors and action handles.

• Syntax of inputs and design of displays.


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3.9.1 Questionnaire for User Interaction Satisfaction (QUIS)

This questionnaire technique is based on the early versions of the OAI

model and covers interface details, such as readability of characters and layout of

displays; interface objects, such as meaningfulness of icons; interface actions, such

as shortcuts for frequent users; and task issues, such as appropriate terminology

and screen sequencing [4].

Appendix C contains the long form, which is designed to have two levels of

questions: general and detailed. If participants are willing to respond to every item,

then the long form questionnaire can be used. If participants are not likely to be

patient, then only the general questions in the short form need to be asked.

3.10 Acceptance of the Test Explicit acceptance criteria should be established when the requirements

document is written or when a contract is offered, rather than using the vague and

misleading criterion of “user friendly. Measurable criteria for the user interface can

be established for the following [14]:

• Time for users to learn specific functions

• Speed of task performance

• Rate of error by users

• Users retention of commands over time

• Subjective user satisfaction

In a large system, there may be eight to ten of such tests to carry out on

different components of the interface and with different user communities. Other

criteria, such as subjective satisfaction, output comprehensibility, system response

time, installation procedure, printed documentation, or graphic appeal, may also

considered in the acceptance of the tests of complete commercial products.


52

After successful acceptance testing, there may be a period of field testing

before national or international distribution.

3.11 Evaluation during Active Use These evaluations happen when the system is released and is used by

targeted users in a real context. The purpose of these evaluations is to better

understand how the system impacts organizational, group, and individual tasks and

activities [22]. Such evaluations can further guide and change the design of future

systems. These evaluation techniques are out of the scope of this thesis.

CHAPTER FOUR

IMPLEMENTATION OF HCI

FOR SCADA SYSTEM

Chapter Four: IMPLEMENTATION OF HCI FOR SCADA SYSTEM

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CHAPTER FOUR

IMPLEMENTATION OF HCI FOR SCADA SYSTEM

4.1 Introduction Once all aspects of successful human computer interface development have

been specified, a SEMATIC WinCC HMI is used to design and implement human

computer interface and SCADA modules for electrical power generation system.

4.2 Case Study: The Electrical Power Generation System Designing an effective and interactive human computer interface of the

supervisory control and data acquisition system (SCADA) for electrical power

generation stations has been selected as a case study in this thesis. The project

consists of similar twenty six electrical power generation stations distributed in

different sites all over Iraq as shown in Figure 4.1. These stations or sites are

supervised by a master station at Baghdad.

According to the software life cycle, the software requirements must be

defined before starting the design process of human computer interface. The

customer, National Dispatch Center (NDC), request to collect performance and

condition information on essential stations equipments, such as generators, feeders

and fuel, and stores the information for future reference. This time based data will

be used to perform specialized function and provide decision making guidance to

operators, maintains planer and engineering.


55

Figure 4.1: Locations of the electrical power generation stations

The requested information is classified as two categories, instant and daily

information as shown in Table 4.1 [2].

Information Type Description

Instantaneous Information - Instantaneous power generated by stations generators. - Instantaneous total power generated by each station.

Daily Information - Pressure readings of stations generators. - Generators temperature readings for all stations. - Working hours for each station. - Power generated frequency for each station. - Stations fuel and oil levels. - Generators working hours. - Power readings of stations feeders.

Notes - Allow operator to write a note during his work shift. Table 4.1: Customer software requirements

In this thesis, an attempt is made, to design an effective and interactive

human computer interface (HCI) by following the Guidelines, Principles and


56

Theories stated in Chapter Two. In order to manage the design process the three

pillars shown in Figure 2.1 can help to produce an order of magnitude speedup in

the process and can facilitate the creation of excellent human computer interface.

The second pillar in the figure is the user interface software tools so the

decision is choosing the Simatic WinCC developed by Siemens Company as a user

interface management system (UIMS) to design the case study pages or screens

and thus the resultant HCI possesses standard features that already the Simatic

WinCC have.

An understanding of user’s skills with interfaces and with the application

domain is important as explained in section (2.3.1). For example, a generic

separation into novice or first-time, knowledgeable intermittent and expert frequent

users might lead to insert or omit some features to the user interface design.

Designing for one class is easy; designing for several is much more difficult [4]. In

this case study the users could be classified into two classes, Novice and Expert

frequent users, Novice users are distributed all over the 26 power generation

stations. Those users have low computer skills, intermediate education, so the basic

strategies is to permit a multi-layer (sometimes called level-structured or spiral)

approach to learning [6]. So there are three access levels to the proposed HMI of

the case study, operator, monitor and administrator. The highest level,

administrator, is allowed to the expert frequent users, working at the master station

at Baghdad, who have high computer skills and higher education in electrical,

computer and control engineering. This type of users has all the rights for

monitoring and controlling the plant.

In order to simplify expert frequent user’s job, a monitoring button is added

upon customer request (NDC) to allow a quick revision of the 26 power stations

readings. Also, a home button has been added to the main tool bar in order to allow

the administrator to switch from one station to another.


57

The novice users, operators, are only allowed to log in to the HMI pages or

screens of their stations except report, trend and system pages.

The accessing level privileges are defined by a user name and password in a

logging dialogue box. This logging procedure adds a security feature to the HMI

and protects the system from unauthorized access.

The proposed SCADA Master Station Software should be able to perform the following activities: data receiving, data transmission, data processing, alarm identifying, updating database, communicating with the operator, recording historical data, and detecting hardware and software failures (Appendix A) [36]. Also SCADA HCI should be capable of display the system information in two formats, tabular and graphical. These two formats are broken into pages in an understood manner.

4.3 Communication System The communications network is intended to provide the means by which

data can be transferred between the central host computer servers (master station at

Baghdad) and the field-based RTUs (at the 26 power generation stations). Very

Small Aperture Terminal (VSAT) modems are used to connect the remote sites to

the host, an on-line operation can also be implemented on this technology [2].

Very Small Aperture Terminal (VSAT) technology has advanced to the

point where a much smaller antenna (down to about one meter) can be used for

Ku-band communications. This has resulted in the Ku-band being preferred for

sites with modest communications requirements. VSAT technology is advancing

steadily, and the capital costs have dropped substantially. Continual time-of-use

charges must be considered in the use of satellite communications. Developments

in this area are investigated when making a decision on the use of this technology.

Table 4.2 shows the satellite system advantages and disadvantages [36].


58

Figure 4.2 depicts the configuration of the WANs-interconnected proposed

SCADA systems. Deployed over WANs, the system has a dedicated satellite link

service at master station with shared satellite link services at the 26 sites. All the

required servers, firewall and monitoring screens are located in the master station

and connected through Ethernet network [2].

Advantages Disadvantages

Wide area converge Easy access to remote sites Cost independence of distance Low error rates Adaptable to changing network Patterns No right –of- way necessary, earth stations

located at premises.

Total dependency on a remote facility Less control over transmission time delay Transmission time delay Reduced transmission during solar equinox Continual leasing costs

Table 4.2: Advantages and disadvantages of satellite system

Figure 4.2: The communication system connecting the master station with the

electrical power generation stations


59

4.4 Master Station The master station or central host computer is a network of computer servers

that provide a man-machine operator interface to the SCADA system. The

computers process the information received from and send to the RTU sites and

present it to human operators in a form that the operators can work with. Operator

terminals are connected to the central host computer by a LAN so that the viewing

screens and associated data can be displayed for the operators [2].

The SQL server is used for storing the online data that the 26th power

generation stations sent and all the data are archived. Moreover, there is a backup

SQL server connected to the network to make sure no loss of data [2].

4.5 Electrical Power Generation Station (field data interface devices) Field data interface devices form the “eyes and ears” of a SCADA system [36].

Devices such as voltage and ampere meters, hours counter, oil pressure gauge, oil

pressure indicator, and so on all provide information that can tell an experienced

operator how well the power generating station is performing. In addition, buttons

such as on/off buttons can be used to form the “hands” of the SCADA system and

assist in automating the process of power generation status.

Figure 4.3: Communication description of power station [43].


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Remote terminal units installed in electrical power generation stations

interconnect the master station computers system over the WANs. The electrical

power generation station RTUs’ provide the master station with on-line data at all

times using IP technology [2].

4.5.1 Power Station Specifications

Each of the electrical power generation stations contain eight generators

manufactured by SEDMO French Company and can generate electrical power up

to 9.6MW per station. The station site can be divided to the following sections or

zones [43];

- Engine - Alternator zone.

- Control and circuit barkers Cabinet.

- Fuel and Oil tanks zone.

The generator machine engines and the coupled alternators are controlled

and monitored by PLC’s for each machine system. These PLC’s are supervised by

a commander PLC which helps to start and rise up the electrical power generation

operation through touch pads and monitor operation status, events and alarms

through LCD display as shown in Figure 4.4 [43].

Figure 4.4: SEDMO Commander control panel.


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Engine Control Unit (ECU), which is connected to the commander control

panel, features the following engine governing and control functions:

- Start sequence control.

- Speed governing.

- Acquisition of a load pulse signal for preparation of load connection.

- Adjustable speed drop.

Engine Control Unit ECU also performs the following monitoring tasks:

- Engine Oil pressure and temperature.

- Engine Coolant temperature.

- CR pressure.

- Nominal speed to allow operation as a 50 Hz generator set (i.e. generator

voltage frequency).

- Engine working hours.

- Transmission of all warnings and alarms to the monitoring and control

system.

- Automatic shutdown in case of limit value violation.

The defects that indicate alarms can be classified as mechanical and electrical

defects. These defects are as follows:

- Mechanical defects:

- Mechanical bearing; Excessive heating of main bearings.

- Abnormal temperature; Excessive heating of alternator housing.

- Vibration; Excessive vibration and noise coming from the machine.

- Electrical defects

- Absence of no-load voltage on start.

- Voltage is too low

- Voltage is too high.

- Voltage oscillation.


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- Proper no-load voltage and excessively low load voltage.

- Loss of voltage during operation.

4.6 Defining SCADA Modules The proposed SCADA software product consists of different modules as

shown in Figure 4.5. These modules can be classified into SCADA modules and

SCADA supporting programs as shown in Figure 4.6.

Figure 4.5: Proposed SCADA Software Product

HMI Module

.pld file .pld file

.pld file

Graphic Designer

SQL Engine

Archive Engine

Report Module

Alarm Module

Tag Logging Module

Trending Module

ADO

OLE DB ADO

OLE DB

Plant Program (RTU)

System Operator

Graphic Developer

Tag DB

System (Shared)

DB

Archive DB Real

Data Storage

Application Module

(VB Script) DB Protocol

ADO

OLE DB

HCI Module SCADA Module RTU Module (26 Module)

Draw

R/W

Read R/W


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Figure 4.6: SCADA Software Classification

4.6.1 Graphic Designers

With WinCC’s graphics designer editor, graphical user interface (GUI) for

the case study is created quickly and easily, screens are created first, insertion and

configuration of objects is done as a second step, finally a navigation page is

designed. These screens are saved in files, these files extensions are (.pld).

Figure 4.7: Graphic Designer Editor [44]

SCADA Software

SCADA Supporting Programs

SCADA Modules

Data Management Modules

Data Processing Modules

HCI Modules Help Plant

HMI Graphic Designer Tag Logging Module

Report Module

Trending Module

Alarming Module

Events Module

Trends Table

Archive Management

Application Module

Alarms Table

Logging Table

Events Table

Reports Table Manipulation Current Data


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Figure 4.8: Graphic Designer flowchart

Run WinCC Explorer

End

Graphic Designer is started and new picture is opened

Select the command Open in the context-sensitive menu the

“Graphic Designer” entry

Standard a blank picture is displayed file format .pdl

Set picture frame dimensions (x and y values)

Select object type from “Object Palette”, “standard” or “Context”

Move the cursor to the position where the object to be inserted

Insert the object with the required size

Open “Object Properties” window. Click on “Properties” tab

Set object static values

Back to “Object Properties” window Click on “Event” tab

Set object dynamic properties

Draw new object ?

Save picture

Start

Yes


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An active X container with thousands of library Symbols and Smart Objects,

VBA, On-line Changes, Panning, Zooming, Layering, Tool Tips and other features

provided with faster development times with more intuitive interface enable the

user to create and modify screens in both modes on-line and off-line [44]. Figures

4.7 and 4.8 show the Graphic Designer Editor Screen and flowchart respectively.

4.6.2 Plant Program

This program is a demonstrational program; it is neither a remote station

simulator nor a plant simulator. The real data were already taken from the 26

power generator stations database and stored in SQL server. The Plant program

will send the contents of these files to the system (shared) database stored at SQL

server (the plant program will send the real data by reading one row each ten

minutes to the shared data base) and then to the application module.

The other function of plant program is accepting control-actions being sent

by the application module.

4.6.3 Report Designer Module

The Hourly, Daily, Weekly, operator’s shift reports and other user-defined reports can be configured within WinCC [2]. The report of designer editor is included within WinCC and can also be used in conjunction with the cross-reference utility to provide an overall application document. WinCC is self documented; configuration report could be setup and run on a document. Print job could be set up to schedule and print reports, WinCC provides a control that allows user to manage and print reports directly from a run time screen [44].

The report designer module will read analog readings of each database element every one minute and store them in an archive file, i.e. the archive file will contain 24*60 values for each database element every day.


66

The first report is called Daily report. Report designer module will calculate the average operating value of each element per hour during a day and store the result in the Daily archive file, i.e. the Daily table will contain 24 values for each database element every day.

The second report is called Weekly report. Report designer module will calculate the average operating value of each element per day during one week and store the result in the Weekly table, i.e. the Weekly table will contain 7 values for each database element every day. It is obvious that the record-interval is one week and this interval is specified by operators.

The Report designer module will generate the system production report (8 clock report). System production report is calculated by summing the analog values of the instantaneous generated power of each station during the period of 12:00PM to 12:00AM. The file contains 30 values of each station at a day. These reports are stored in an archive file.

Figure 4.9: Report designer editor [44] 4.6.4 Trends Module

Trends show how process values change over time. This module displays the

trends in the way most useful to the operator. Trends can be set up as graphs,


67

tables, or other formats. It also provides analysis tools for the operator to allow

zooming, historical data viewing. Trends are graphical plots of values from current

conditions (real time) and past condition (historical). Wizards are used to setup

these trends to be modified during runtime, including the addition of tags to be

trended [44]. The trend display object provides the user with the template for

representing tag values as trends. This object is setup during configuration and can

be modified by the operator during the runtime process.

Figure 4.10: Trend creation steps

4.6.5 Alarm Generation Module

Visualization of the process includes the ability to inform the operator when

conditions are outside their normal ranges [44]. Alarm logging editor allows user

Open project through WinCC explorer

Click on Graphical Builder

Select “trend.pld” page, right click and Open

Select WinCC online trend Control

Set the following properties;- Window name. - Data Source/Tag. - define X and Y axis.

Click on Curve tab Add required trends

Name trends Set tags connection

Apply and Save page


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to easily configure alarm messages that are generated for defined process states,

both binary and analog messages could be done configured and created.

Figure 4.11: Creation Discrete and Analog Alarms

Digital alarm conditions are displayed in an alarm screen. Alarm resolution

actions for the operator can be defined here as well. Analog alarm can be set off of

a single tag. Operator actions to take are defined here as well. Alarms and events


Click on Alarm Logging, right click and chose OPEN

Alarm Logging window

Append new Alarm

Select Discrete or

Analog Alarm

AnalogDiscrete

Right click on Analog alarm icon and press new

Access alarm properties

Click Parameters Tab to configure alarm

Set type and class of alarm, connect TAG to be monitor

Define message number

Tag window will appear

Set the TAG to be monitor

Set the Upper/Lower limits

Define message number

Click Text tab, define info message and message appear

Click TAG Action, define page name when alarm occurred

Save and Exit


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are stored in the local SQL server 2000 database. Settings include archive and

segment size, time range, and backup path.

4.6.6 Achieving Module

The basic tasks of the archiving system are to display current process values

at any time. However, displaying the chronological progression of a process value,

e.g. in a diagram or table, need to access to past process values [44]. These values

are stored in process value archives. The process value archiving system consists

of configuration and runtime components. The configuration component of the

archiving system is the Tag Logging editor. In there process value is configured

and archives are compressed, defining acquisition and archiving cycles and selects

the process values to be archived.

The runtime component of the archiving system is responsible for writing

the process values to be archived to the process value archive during runtime. Vice

versa, Tag Logging Runtime is also responsible for reading the archived process

values from the process value archive.

4.6.7 Data Base Modules

The SQL Server 2000 relational database engine is a modern, highly

scalable, highly reliable engine for storing data. The database engine stores data in

tables. Each table represents some object of interest to the plant. Each table has

columns that represent an attribute of the object modeled by the table and rows that

represent a single occurrence of the type of object modeled by the table. There are

three main data base modules in this case study.


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4.6.7.1 System Database

This module contains the Plant real database gathered from the remote

(PLC) in the 26 power generation stations distributed in different sites all over the

country and demonstrated by the Plant program. The system database contains

three tables. One of the tables has attributes which refer to the readings related to

the station such as; station ID, main positive, main negative, oil and fuel levels, etc.

The attributes of other table are related to the eight generators in the 26th power

stations such as; generators ID’s, power generated readings, generators status and

other related readings, while the third table contains attributes of station number

correlated to the station name.

4.6.7.2 Archive Database

The Archive database is responsible for storing and retrieving historical

database used by other modules like report and trending modules. This module

contains many tables such as: Trending tables, Report tables, Event tables, Alarm

tables and Logging tables.

4.6.7.3 Tag Database

This module contains information received from the application module

each one second or information referred to memory location in system database

All the above modules used SQL server 2000 engine to store and retrieve

information and the mechanisms for the manipulation of information are the same

in all modules as mentioned in chapter three, ADO is application level interface

with a consistent design across many programming environments.


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4.6.8 Application Module

This module responsibilities are: send/receive data to/from the system

(shared) database, does all necessary calculations on these data, and updates

system database with real-data values.

4.6.9 HMI Module

HMI is a GUI program that is constructed from a window and represents an

HMI page plus several bars; the most important one is an HMI main bar and

navigational bar. HMI displays visually SCADA system on the screen, updates the

screen according to the current values, states and handles all operators’ inputs. For

complete plant visualizations the GUI must communicate efficiently with the plant

elements (stored in system database) by adding drivers and creating tags, tags are

objects that refer to memory location (address) typically found in PLC, once a tag

is defined it contains all the properties relevant to its status, this includes

information obtained from the channel/ driver and memory location. WinCC tags

allow graphics objects, trends, and alarms to be connected directly to relevant

process data. HMI pages are discussed below.

4.6.9.1 HMI Main Page

This is the first page that will be displayed when HMI is first executed, as

shown in Figure 4.1. This page can also be displayed using “Home” command in

the HMI Main bar. In this page allocation of all the 26 power generation stations

which are distributed all over the country is displayed, moreover a menu on the left

hand side of the main page lists the names of the 26 power generation stations, an

operator could choose the station that he want by double clicking either the icon on

the map or the station’s name on the menu list. There are also two buttons on the

left upper corner which enable the user to enter the sites either as a monitor i.e.


72

(quick revision) or as an administrator with additional rights. There are also four

buttons on the upper right corner: help, refresh, home, and login/logout. Help

button is used to display description about each button in the HCI project, refresh

button is used to refresh the screen upon user’s request, home button displays the

main page as mentioned above, while login/ logout button facilitates the user’s

entry or exit to and from the HCI pages.

4.6.9.2 Navigation Page

Runtime navigation is an important part of the HMI application. Operators

should be able to quickly access specific areas of application as needed. A

navigation screen can be created using standard buttons and picture window

objects, then using direct connection feature to create dynamics with one click of

the mouse. Click buttons are used to change the current process screen being

displayed by a picture window object. Additional browser features for runtime

navigation is added such as “Home” and “Refresh”. This page allows operators to

easily move from screen to screen through six navigation buttons, these buttons

are: Schematic, database, Event/Alarm, Report, operator and System.

Figure 4.12: Navigation screen


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Another navigation buttons called internal navigation enables the operator to

access the information about plant’s elements easily. These buttons are:

Generators, Stations and Oil &Fuel.

Figure 4.13: Administrator navigation flowchart

START Double click Power-plant

shortcut on desktop

Monitoring Review stations short information

Administrator Monitor and control all stations

Operator Monitor and acknowledge certain station

Schematic Control station generators and feeders

Database Monitor station generators and feeders

Alarms and Events Review occurred alarms & events

Monitoring Review stations short information

Control and Monitor Select a station

Reports Generate data reports & graphs

Operator Review operators notes

Generator Monitor station generators

Station Monitor station feeders

Fuel & Oil Monitor levels

Generator Control station generators

Station Control station feeders

Fuel & Oil Control levels

Report Generate data report

Trend Generate data graphics

Generator Review generators data

Station Review feeders data

Events Review actions

Alarms Review & Control alarms

System Monitor network connection

Home Main page

Enter user name and password to login


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Figure 4.14: Operator navigation flowchart

4.6.9.3 HMI Schematic Pages

Schematic pages contain schematic diagrams of the plant, as shown in

Figure 4.15. The main feature of this page is to mimic the real environment i.e.

(power generation station) configuration on the scheme pages, the generators

image shown in Figure 4.15a is the same as it is in the real environment and this is

tested by using usability test method, and this is true for the other images Figures

4.15b and 4.15c.

Schematic pages consist of objects. Each object represents an element in the

plant. Two types of objects can be recognized in schematic pages: digital objects,

and analog objects. Digital objects are symbols that represent plant devices. Digital

Objects give the current states of a device through colors. Analog objects are

values that represent analog readings in the plant. Analog objects are values that

represent analog readings in the plant. Analog objects give the current states of a

device through values as well as colors, as shown in Table 4.3. As one can see

from the tables, the red color stands for all kinds of errors that may happen in the

Operator Monitor and acknowledge

certain station

Schematic Acknowledge control signal

Database Monitor station generators and feeders

Generator Monitor station generators

Station Monitor station feeders

Fuel & Oil Monitor levels

Station Acknowledge feeder’s status

Fuel & Oil Acknowledge levels

Operator Add operator notes

Alarms and Events Review occurred alarms & events

Events Review actions

Alarms Review & Acknowledge alarms


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plant. Schematic pages will not give the operator an indication about the error type.

The gray color represents objects that are under control. Objects marked gray

indicate the fact that the administrator entered the current state of this element and

this state may not be the same as the current state of the element in the plant.

Objects under control are marked gray until the Remote Station accepts or rejects

the control action and sends the current state of that element.

Color Digital Current State Analog Current State

Green Normal Operation Normal Operation Magenta OFF - Red Error

Alarm Not Available Not Active Not Defined

Low High

Gray Under Control Under Control Manual Entry

Table 4.3: MMI Schematic Pages Color Meanings

Several operations can be done to objects in schematic pages. In order to do

an operation on an object, the user should first select the object by clicking it. The

first operation is the navigation operation. Operator can navigate from one HMI

page to another by double clicking on an object that is linked to a page.

Figure 4.15: Schematic screens


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4.6.9.4 Database Pages

The database elements detailed information can be found in these pages.

They illustrate two types of information, digital and analog, in a tabular form and

have no control. Figure 4.16 shows one of these pages. These pages have been

added to the developed project pages upon the customer request.

Figure 4.16: Database page

4.6.9.5 Alarm/ Event Pages

Alarm/Event pages display system alarms and events. The alarm (or event)

text gives information about the alarm like, time and date of alarm occurrence,

element where alarm is present and a description of the alarm. Color meanings in

Alarm/Event pages are shown in Table 4.4.

Table 4.4: HMI Alarm/Event Pages Color Meanings

Color Meaning Green Event Red Un-Acknowledged Alarm Gray Sending Control Action

Acknowledged Alarm


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Unacknowledged alarms are red. To acknowledge an alarm, the operator

selects the alarm row, click Single Acknowledgment button. The Application

module will acknowledge the element. In the same way group of alarms rows can

be acknowledge by clicking Group Acknowledgement.

Figure 4.17: Alarm/Event screen

4.6.9.6 HMI Trending Pages

The Trending pages display a graphical chart of analog readings versus time,

as shown in Figure 4.18. Trending pages contain trend selection buttons which

help the operator to choose the curve of the calculated or monitored values. The

assigning parameter button is responsible for defining the chart appearance: line,

dots, stepped, full area interpolated chart, etc. also, the operator can select the time

scale to be hourly, daily, or weekly from the x axis tab.

4.6.9.7 HMI Report Pages

Report pages are similar to trend pages in everything except that the report

pages will display element values versus time in a textual format and via a table.

Report pages are: Daily, Weakly, and 8 clock Report. The 8 clock Report shows


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one value for each station. This value represents the average production rate of a

station from 12:00PM to 12:00 AM of the previous day.

Figure 4.18: Trends screen

Figure 4.19: Trend creation steps


Click on Graphical Builder

Select “trend.pld” page, right click and Open

Select WinCC online trend Control

Set the following properties;- Window name. - Data Source/Tag. - define X and Y axis.

Click on Curve tab Add required trends

Name trends Set tags connection

Apply and Save page


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4.6.9.8 HMI System Pages

The system page available in HMI displays the states of computers

connection at the 26 power generation station. The green color represents a normal

state while the red color represents an error state. Error states may be caused by

shutting down a computer or breaking down the WAN communication.

Figure 4.20: System page.

4.6.9.9 HMI Operators Pages

Two types of Operator Pages are available in HMI. The first page is the Add

Note page which enables the operator at the station to record their notes in a text

box. When the operator clicks the “Submit Note” button, the date and time of

entering the note will be added to the recorded note automatically.

The other page is the Operator Existence page which gives record of

operators’ names, station name as well as the date and time. When the operator

clicks “Log In/Out” button on the main bar, a system login window appears

allowing the operator to login by typing a user name and a password. This logging


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operation allows the system to add the operator shift to the table of Operator

Existence page automatically.

Figure 4.21: Operator pages

Chapter Five: HCI AND SCADA SYSTEM TEST

CHAPTER FIVE

HCI AND SCADA SYSTEM

TEST


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CHAPTER FIVE

HCI AND SCADA SYSTEM TEST

5.1 Introduction Interface developers evaluate their designs by conducting expert reviews,

usability tests, surveys, and rigorous acceptance tests. Once interfaces are released,

developers perform continuous performance evaluations by interviews or surveys

[4].

This chapter is divided into three main areas. First, the WinCC hardware and

software instillation requirements are discussed. Second, the expert reviews,

usability and QUIS tests were made to the developed product and their results are

presented. Finally, real data and quality tests that were carried out are presented.

These tests were carried out during various stages of system development process.

Figure 5.1: Conducted tests of developed product

Installation Requirements

of WinCC

Expert Reviews

- Cognitive walkthrough technique - Heuristic evaluation technique

Usability Testing

Questionnaire for User Interaction Satisfaction

(QUIS)

Running the SCADA

Product

Quality Test of Developed Product


83

5.2 Requirements for the Installation of WinCC For the installation of WinCC, certain hardware and software are required

[44]. These requirements are outlined in the following hardware and software

installation requirements sections.

During the installation of WinCC, the users will check, whether certain

requirements have been met. The following will be checked:

• Operating system.

• User rights.

• Video resolution.

• Internet Explorer.

• MS Message Queuing.

• SQL Server.

5.2.1 Hardware Requirements for the Installation of WinCC

WinCC supports all current IBM/AT-compatible PC platforms. In order to

be able to work efficiently with WinCC, a configuration should be setup according

to the recommended computer specification as shown in Table 5.1. The table

shows also, the different computers used to test the developed product.

Item Recommended Used

CPU Intel Pentium 4, 1400MHz Intel Pentium 4, (1800MHz, 2200MHz and 2700MHz)

Main Memory 512MB 512MB and 1GB Available Hard Disk Speace 10GB 20GB Video Card 32MB 32MB and 64MB Color depth True Color True Color Resolution 1024*768 1024*768

Table 5.1: Recommended and used computers specifications


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5.2.2 Software Requirements for the Installation

For the installation of WinCC, certain requirements with regards to the

operating system and software configuration have to be met. Before the installation

of WinCC, the MS Message Queuing Services and the SQL Server 2000 instance

“WinCC” need to be installed. A WinCC runs under Windows XP professional and

Windows 2000, and the developed product was tested with both operating systems.

5.3 Expert Reviews A way of finding out how well a system is designed is by asking experts of

their opinions. There are a variety of expert-review methods to choose as

mentioned in section (3.7). In this thesis two methods are selected and applied to

evaluate the developed HCI, cognitive walkthrough technique and heuristic

evaluation methods.

5.3.1 Cognitive Walkthrough Technique

This technique was applied to test the developed product. The steps involved

in cognitive walkthrough technique for monitoring task evaluation are shown in

Appendix (B1).

The evaluation of the developed HCI is continued to examine each task of

the developed product. Table 5.2 shows some of the tested tasks. Negative answers

to any of the questions are carefully documented on a separate form, along with

details of the system, its version number, the date of the evaluation, and the

evaluators’ names. The interface for the developed product may have been

changed since the evaluation was done. While working through the interface the

problems identified must be recorded and prioritized and finally solutions must be

suggested [22]. All the negative answers shown in Table 5.2 below are reviewed

and the suggested solutions are used to revise the design of the product.


85

Number of Examined task Steps Questions Negative Ans.Monitor generator status 2 4 None Control generator status 4 11 1 Control power’s station 3 9 None Control Fuel & Oil levels 3 9 1 Report monitoring 3 10 2 Trend monitoring 3 10 2

Table 5.2: Some of the examined tasks for administrator login using cognitive

walkthrough evaluation

5.4 Usability Testing Many variant forms of usability testing have been explained in section (3.8).

In this thesis Competitive Usability test was applied to the developed product by

letting three users work on the previous product of AlQurashi bureau and the

developed product, Table 5.3 shows a summary of comparing results that were

obtained:

Previous Product Developed product - Many mistakes are done by novice users (at the 26 Power Generation Stations) because the pages or screens do not mimic the actual plant.

- There are no mistakes because the pages or screens mimic the actual plant as in Figure 4.15.

- The expert users at master station draw the charts manually.

- There are trend pages or screens which facilitate the users task

Table 5.3: some of comparing results for three users worked on the developed and

the previous product

5.5 Questionnaire for User Interaction Satisfaction (QUIS) The Questionnaire for User Interaction Satisfaction (QUIS) was developed

by the University of Maryland, Human Computer Interaction Laboratory, as shown


86

in Appendix (C), is one of the most widely used questionnaires for evaluating

interfaces [22]. Although developed for evaluating user satisfaction, it is frequently

applied to other aspects of interaction design. An advantage of this questionnaire is

that it has gone through many cycles of refinement and has been used for hundreds

of evaluation studies, so it is well tried and tested.

This test was carried out with the aid of fifteen volunteers (users). Four

females, eleven males were subjected to this test. The ages of these persons were

between 22 and 38 years. The test was conducted according to the following

points;

• System experience (i.e., time spent on the system)

• Past experience (i.e., experience with other systems)

• Overall user reactions

• Screen design

• Terminology and system information

• Learning (i.e., to operate the system)

• System capabilities ( i.e., the time it takes to perform operation)

• Technical manuals and online help.

• Software installation

The QUIS used to collect answers has a 9-point scale, where the highest

scale shows a good impression. It also includes NA (Not Applicable) as a category

[4]. Some questions fall into range of possible values, for gender there are two

possible answers; female or male. Other questions require a specific value,

such as age, number of hours using a software product [14].

User’s performance on the structured tasks was analyzed in detail and

participant ratings were tabulated as shown in Table 5.4.


87

Activity that received an average rating below 4.5 across participants was

deemed to need detailed review. In this case study the task “Learning; Exploration

of features by trial and error” received an average rating of 3.6. This received

value was expected, since the developed project was classified as a life

critical system and no trial and error is allowed.

0

1

2

3

4

5

6

7

8

9

10

Overall UserReactions

Screen Terminology andSystem Information

Learning System Capabilities User Manuals andOn-line help

SoftwareInstallation

Structured Task

Ave

rage

Figure 5.2: QUIS structured tasks averaging

Figure 5.2 shows a bar chart to display averaging of structured tasks

graphically. Some tasks received high rating, more than 7.5 in 9-point scale format,

such as; overall user reaction, screen, terminology and system information, system

capabilities, and software installation. Other tasks received rating near 7. The

overall average of these main received tasks was 7.88.

Scaling the average rating on the standard scaling; 9-8.1 is excellent while

rating 8.1-7.2 as very good, 7.2-6.3 as good, 6.3-5.4 as medium, and 5.4-4.5 as

pass, while below 4.5 is not acceptable.

Based on the scaling mentioned above, four of the main tasks received a grade of

excellent; one main task received a grade of very good while the rest received

grade of good. The overall average of main tasks is found very good.


88

Participant number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Average

Background Information

Age 27 38 36 26 25 25 22 24 30 34 32 28 35 37 23 29.47

Sex M M F M M F F F M M M M M M M 4F,11M

Hours of work on this system 10 12 8 3 2 1 1 1 3 12 5 5 1 1 1 4.4

How many operating systems worked

with 1 2 2 1 1 1 1 1 2 2 1 1 2 2 1 1.4

Number of familiar devices &

software 20 22 20 18 15 13 12 12 12 15 8 9 18 22 10 15.07

Structured Tasks

Overall User Reactions

Terrible / wonderful 9 9 8 9 8 7 9 9 8 9 9 9 8 8 8 8.47

Frustrating / satisfying 9 9 9 9 8 8 9 9 9 8 9 9 7 8 8 8.53

Dull / stimulating 9 9 9 8 8 8 6 7 9 9 9 9 8 8 9 8.33

Difficult / easy 9 9 8 9 9 9 8 8 8 8 9 9 9 9 9 8.67

Inadequate power / adequate power 8 8 8 8 8 7 9 9 9 8 9 9 8 8 8 8.27

Rigid / flexible 9 9 8 8 8 9 7 7 9 8 9 9 8 8 9 8.33

Screen

Characters on the computer screen 9 9 9 9 8 8 9 9 9 9 9 9 8 8 8 8.67

Highlighting on the screen NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA


89


Screen layouts were helpful 8 8 9 8 8 9 9 9 9 9 9 9 9 9 8 8.67

Sequence of screens 9 9 9 9 8 9 8 8 8 9 9 9 9 9 9 8.73

Terminology and System

Information

Terminology relates well to the work 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

Messages which appear on screen 8 7 9 8 8 9 9 8 8 8 9 9 9 9 9 8.47

Computer keeps informing what it is

doing 9 9 9 8 9 8 9 7 7 8 8 9 8 9 9 8.4

Error messages 8 8 9 8 8 8 8 8 8 8 9 9 7 9 7 8.13

Learning

Learning to operate the system 9 8 9 9 9 8 9 8 8 8 9 9 8 8 8 8.47

Exploration of features by trial and

error 5 4 4 5 3 4 4 3 3 3 4 4 3 2 3 3.6

Remembering names and use of

commands 9 9 8 9 8 8 7 7 8 7 8 8 8 8 8 8

A straight-forward manner

performing tasks 8 9 8 9 8 7 8 7 8 7 7 7 8 8 8 7.8

System Capabilities

System response time 8 7 8 8 8 8 8 7 7 8 9 9 8 8 8 7.93

The system is reliable 9 8 8 9 8 8 8 8 8 8 9 9 8 8 8 8.27


90


System tends to be quiet 9 9 8 9 9 8 8 8 8 8 9 9 8 8 8 8.4

Correcting mistakes easy 7 8 8 8 8 7 8 7 7 8 9 9 8 7 7 7.73

Ease of operation depends on your

system experience 5 7 6 7 5 5 5 6 6 5 8 9 7 7 6 6.27

User Manuals and On-line help

Technical manuals are clear NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA

Manual information is easily

understood NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA

Amount of help given adequate 7 9 8 8 7 6 7 6 6 7 6 6 6 7 6 6.8

Software Installation

Speed of installation 9 9 8 9 8 7 7 8 8 7 − − 8 8 8 8

Customization 8 8 8 8 8 7 8 8 7 7 − − 8 8 8 7.77

Informs you of its progress 8 9 8 9 8 8 8 8 8 8 − − 8 9 8 8.23

Gives a meaningful failures

explanation 9 9 8 9 8 8 8 8 8 8 − − 9 8 8 8.31

Participant Average 8.26 8.33 8.15 8.37 7.85 7.67 7.85 7.63 7.78 7.74 8.43 8.52 7.85 7.96 7.85

Table 5.4: Participant information and ratings on structured tasks of the developed product


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5.6 Running the SCADA Product The basic components of SEMATIC WinCC are the configuration software

and the runtime software. The WinCC Explorer is the core of configuration

software. In the WinCC Explorer, the proposed project structure is displayed and

managed. Special editors are provided that can be accessed from WinCC explorer.

With each editor, pages or screens of the developed product are configured; with

the run time software one can test all system modules by logging as an

administrator. The developed product was tested with real data taken from

AlQurashi Bureau. Figure 5.3: shows the Monitoring screen with real data test.

Figure 5.3: Monitoring screen at real data test


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The developed product also has the ability to test one module separately as

the steps shown below:

- Run the graphic designer editor, and open the module default page.

- Click on Activate Runtime button located on file menu.

5.7 Developed Product Quality Test The developed SCADA modules were tested to see their general behavior.

The results of the test are as follows:

• The SCADA modules agree with their requirements.

• The SCADA modules are almost error-free.

• The quality of the final HCI software is enhanced significantly due to advanced

SEMANTIC WinCC features, developed by Siemens, such as:

- SEMATIC WinCC consists of four major subsystems (the graphic system,

the alarm system, the archiving system, and the report system).

- WinCC applications can support the visualization, control, and data

management needs of the plant. WinCC’s graphic libraries and wizards

make developing machine control applications a breeze.

- WinCC’s networking capabilities provide instant access to the application

from any location, making WinCC ideal for remote applications.

These WinCC advanced features enhanced the developed project through

enhancing the following factors;

• Modularity: The developed project was created using the four WinCC

subsystems.


93

• Expandability: Since the HCI modules are almost independent of each other,

expanding each module to support enhanced features will not have effect on

other modules, leading to increase HCI expandability.

• Modifiability: The interface developed by the SIMANTIC WinCC can be

modified easily.

• Understandability: Understanding completely separated modules are easier than

understanding one huge module.

• Attractiveness: The WinCC Graphical Designer library objects and icon images

are aesthetically pleasing.

• Prevention: The developed product provides some prevention by “graying out”

certain menu. In addition the product supports error handling.

• Structure guidance: the developed product provides button information help,

which explains the buttons functions.

• Rapid prototype to support expert-review and usability- testing processes: The

WinCC graphic designer facilitates rapid prototyping of user interface, since the

designer can try several alternative solutions within a short time. In addition,

the users can give their suggestions about the final product from the early stages

of software life cycle.

CHAPTER SIX

CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK

Chapter Six: CONCLUSIONS AND SUGGESTION FOR FUTURE WORK

95

CHAPTER SIX

CONCLUSIONS AND SUGGESTIONS FOR FUTURE

WORK

6.1 Conclusions

In this thesis, an attempt is made to study strategies for designing an

effective human computer interaction (HCI). A number of conclusions have

been drawn from this study. These include:

• There are three pillars for successful user-interface development: (i)

guidelines documents and processes; (ii) user’s interface software tools; and

(iii) expert review and usability testing (Figure 2.1). These pillars can help

user interface architects to turn good ideas into successful systems. They are

not guaranteed to work, but experience has shown that each pillar can

produce an order-of-magnitude speedup in the process and can facilitate the

creation of excellent systems.

• Guidelines documents usually record best practices, and are derived from

practical experience or empirical studies with appropriate example, whereas,

principles tend to be more fundamental, widely applicable, and enduring.

However they also tend to need more clarification.

• Both design principles and guidelines emerge from practical experience and

empirical studies. Designers can benefit from reviewing available guidelines

documents before constructing local versions.


96

• In addition to recording organizational policy, a “guidelines document”

supports consistency, aids the application of tools for user-interface building,

and facilitates training of new designers. It also records results of practice

and experimental testing, and stimulates discussion of user-interface issues.

• Determining user’s skill is one of the most important HCI design principles.

In this thesis, users are classified into novice (or first time) and expert (or

frequent) users, and the basic strategies used -in this thesis- are such that

they permit a multi-layer (sometimes called level-structured or spiral)

approach.

• Bringing usability into the design process is the aim of interaction design. In

essence, it is about developing interactive products that are easy, effective,

and enjoyable to use from the user’s perspective.

• Effective human computer interaction design is multidisciplinary, involving

many inputs from wide reaching disciplines and fields.

• Development methodologies such as LUCID or contextual design (designing

systems with the user in mind) help by offering validated processes with

predictable schedules and meaningful deliverables and hence support

usability.

• Although user interface management system (UIMS) provides increased

support, it also has some constrains.

• Most testing methods will account appropriately for normal usage, but

performance in unpredictable situations with high levels of input is

extremely difficult to test.

• Evaluation is a continuous process, and should occur (i) during the entire

system development process; (ii) after the system is finished; and (iii) during

the period the system is actually used.


97

• Schedules often dictate when the evaluation ends. Otherwise, evaluation

should be ended when similar patterns of behavior being repeated and no

new things emerging or nothing new to learn.

6.2 Future work • The use of a Web technology feature of the Sematic Win CC software tool

developed by Siemens in the developed project. This will help in supporting

portability, opening the system architecture, utilizing open standards and

protocol such as internet protocol (IP).

• Improving the on-line help of the developed product. This can be achieved

by clear writing, easy understood and helpful technical manual.

• The user interface during active use should be evaluated. This can be

facilitated by interviews or surveys, or by logging users’ performance in a

way that respect their privacy.

• Evaluation and critiquing software tools should be used to capture the

numbers of displays, widgets, or links between displays and users’ patterns

of activity.

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[46]Sidney L.Smith,” Standards versus Guidelines for Designing User

Interface Software”, Journal of Behavior and Information Technology,

Taylor and Francis, Ltd. 1986.

[47] Stephen R. Schach, ”Introduction to Object Oriented Analysis and

Design”, Mc Graw. Hill, 2004.

[48] Suyeong Kim, “Theory of Human Intervention and Design of Human

Computer Interfaces in Supervisory Control: Application to Traffic

Incident Management” Ph.D. Thesis, Mechanical Engineering

Department, Massachusetts Institute of Technology.1997.

[49] Szekely, Pedro, “Retrospective and Challenges for Model-Base

Interface Development”, Proc. Second International Workshop on

Computer-Aided Design of User Interfaces, Belgium, 1996.

104

[50] Thomas K. Landauer,” Research Methods in Human Computer

Interaction”, Elsevier Science Publishers B.V. 1988.

[51] Xavier Ferre’, Natalia juristo, Helmut Windl ,Larry Contantine,”

Usability Basics for Software Developers”, IEEE Software,2001.

[52] Waleed Khalid, “A Man-Machine Interaction Package for Real-Time

Distributed System”, M.Sc. Thesis, University of Baghdad, 1997.

[53] Wharton, Cathleen, Rieman, John, Lewis, Clayton, and Polson, Peter,

“The Cognitive Walkthrough Method: A Practitioner’s Guide”, John

Wiley and Sons, NY, 1994.

APPENDIX A

SCADA SYSTEM FUNCTIONS

A-1

APPENDIX A

SCADA SYSTEM FUNCTIONS

• Data Receiving

SCADA Master Station Software should be able to receive data from the

Remote Station.

• Data Transmission

SCADA Master Station Software should be able to send control actions done

by the operator to the Remote Station.

• Data Processing

SCADA Master Station Software should be able to identify data, normalize

data, convert data format, and do all necessary data calculation on data being

sent/received to/from the Remote Station.

• Alarm Processing

SCADA Master Station Software should be able to detect system changes

and identify abnormal situations.

• Updating Database

Collected data are stored in system database, where information is available

for SCADA Master Station Software modules. The SCADA Master Station

Software should be able to store/retrieve data from system database.

• Communicating with the Operator

The operator should be able to monitor and control the plant through the

SCADA Master Station Software.

• Recording Historical Data

A-2

SCADA Master Station Software should be able to record historical data for

future use by the operator.

• Detecting Failures

SCADA Master Station Software should be able to detect software and

hardware failures happened in the Master Station itself.

APPENDIX B

WALKTHROUGH AND

HEURISTIC EVALUATION

B-2

APPENDIX B

WALKTHROUGH AND HEURISTIC EVALUATION

Walkthrough Technique This testing technique was used to test the most high frequency tasks.

Task: monitor generator’s status.

Typical user’s: Administrator

The steps to complete the task are given below. Note that the interface for

the developed software may have changed since we did our evaluation.

Step 1. Selecting the correct entry i.e. log in as a monitor.

Q. Will users know what to do?

Ans. Yes –they know that they must “monitor the generator’s station.”

Q. Will users see how to do it?

Ans. Yes – they have seen menus before and will know to select the appropriate

item and click it.

Q. Is the dialogue box of log in user name and password not frustrate the users?

Ans. Yes- they used to do this procedure in the previous software.

Step 2. Quick revision to the generator’s status.

Q. Is the monitoring page or screen presented the generator’s readings in an

accurate and effective manner?

Answer.: Yes the related information was presented in tabular form as they used to

present their information at the NDC.

B-3

Task: control generator’s status.

Typical user’s: Administrator

The steps to complete the task are given below. Note that the interface for

the developed software may have changed since we did our evaluation.

Step 1. Selecting the correct entry i.e. log in as an administrator

Q. Will users know what to do?

Ans. Yes –they know that they must choose administrator button.

Q. Will users see how to do it?

Ans. Yes – they have seen menus before and will know to select the appropriate

item and click it.

Q. Is the dialogue box of log in user name and password not frustrate the users?

Ans. Yes- they used to do this procedure in the previous software.

Step 2. Select the station.

Q. Does the user know how to choose the station?

Ans. Yes-because the main page was designed with geographic representation to

the 26 power generator stations distributed on the Iraq map.

Q. Does he know whether he have chose the correct station?

Ans. Yes- the name of the selected station is written on the top left of the

generator schematic page.

Q. could the user log out from the station if its choose is wrong immediately?

Ans. Yes- he could log out immediately be click the home button.

.

B-4

Step 3. Change the generator’s status.

Q. Is the schematic page so clear to facilitate the user’s task for controlling the

generator’s status?

Answer.: Yes the generator’s schematic page was designed to mimic the real

environment at the 26 power generator stations, so both the administrator

and the operator are familiar with it.

Q. Does the administrator know how to accomplish the task?

Answer. Yes he/she does, there is a toggle switch which the users select and

choose its location from early stage of design process.

Q. Will user’s understand from feedback whether the action was correct or not?

Answer. No- because when the generator’s status is off and the administrator want

to change it to on and the action is not accepted because the generator is

failure there is no feedback message and an indication that the generator

status is failure.

Step 4. Wait for acknowledgement signal from the operator at the selected

workstation to confirm the change in generator status.

Q. Will user understand from feedback whether the action was correct or not?

Answer. Yes- because the controlled generator is become Gray until the operator

at the selected station send acknowledge signal to the administrator at the

master station.

Q. Will users know that the task is completed?

Answers. Yes the controlled generator will take the colors of the toggle switch that

are described in table (4.3).

APPENDIX C

QUESTIONNAIRE FOR USER

INTERACTION

C-2

APPENDIX C

QUESTIONNAIRE FOR USER INTERACTION SATISFACTION

(© UNIVERSITY OF MARYLAND, 1997)

Identification number:

Age: Gender (M for male, F for female):

PART 1: System Experience

1.1 How long have you worked on this system?

_ less than 1 hour _ 6 months to less than 1 year

_ 1 hour to less than 1 day _ 1 year to less than 2 years

_ 1 day to less than 1 week _ 2 years to less than 3 years

_ 1 week to less than 1 month _ 3 years or more

_ 1 month to less than 6 months

PART 2: Past Experience

2.1 How many operating systems have you worked with?

_ none _ 3-4

_ 1 _ 5-6

_ 2 _ more than 6

2.2 Of the following devices, software, and systems, check those that you have personally used and are familiar

with:

_ computer terminal _ personal computer _ lap top computer

_ color monitor _ touch screen _ floppy drive

_ CD-ROM drive _ keyboard _ mouse

_ track ball _ joy stick _ pen based computing

_ graphics tablet _ head mounted display _ modems

_ scanners _ word processor _ graphics software

_ spreadsheet software _ database software _ computer games

_ voice recognition _ video editing systems _ internet

_ CAD computer aided design _ rapid prototyping systems _ e-mail

C-3

PART 3: Overall User Reactions

Please circle the numbers which most appropriately reflect your impressions about using this computer

system. Not Applicable = NA.

3.1 Overall reactions to the system: terrible wonderful

1 2 3 4 5 6 7 8 9 NA

3.2 frustrating satisfying

1 2 3 4 5 6 7 8 9 NA

3.3 dull stimulating

1 2 3 4 5 6 7 8 9 NA

3.4 difficult easy

1 2 3 4 5 6 7 8 9 NA

3.5 inadequate power adequate power

1 2 3 4 5 6 7 8 9 NA

3.6 rigid flexible

1 2 3 4 5 6 7 8 9 NA

Please write your comments about terminology and system information here:

PART 4: Screen

4.1 Characters on the computer screen hard to read easy to read

1 2 3 4 5 6 7 8 9 NA

4.2 Highlighting on the screen unhelpful helpful

1 2 3 4 5 6 7 8 9 NA

4.3 Screen layouts were helpful never always

1 2 3 4 5 6 7 8 9 NA

4.4 Sequence of screens confusing clear

1 2 3 4 5 6 7 8 9 NA

Please write your comments about the screens here:

PART 5: Terminology and System Information

5.2 Terminology relates well to the work never always

you are doing? 1 2 3 4 5 6 7 8 9 NA

5.3 Messages which appear on screen inconsistent consistent

1 2 3 4 5 6 7 8 9 NA

5.4 Messages which appear on screen confusing clear

1 2 3 4 5 6 7 8 9 NA

C-4

5.5 Computer keeps you informed about never always

what it is doing 1 2 3 4 5 6 7 8 9 NA

5.6 Error messages unhelpful helpful

1 2 3 4 5 6 7 8 9 NA

Please write your comments about terminology and system information here:

PART 6: Learning

6.1 Learning to operate the system difficult easy

1 2 3 4 5 6 7 8 9 NA

6.2 Exploration of features by trial discouraging encouraging

and error 1 2 3 4 5 6 7 8 9 NA

6.3 Remembering names and use of difficult easy

Commands 1 2 3 4 5 6 7 8 9 NA

6.4 Tasks can be performed in a straight- never always

forward manner 1 2 3 4 5 6 7 8 9 NA

Please write your comments about learning here:

PART 7: System Capabilities

7.1 System speed too slow fast enough

1 2 3 4 5 6 7 8 9 NA

7.2 The system is reliable never always

1 2 3 4 5 6 7 8 9 NA

7.3 System tends to be noisy quiet

1 2 3 4 5 6 7 8 9 NA

7.4 Correcting your mistakes difficult easy

1 2 3 4 5 6 7 8 9 NA

7.5 Ease of operation depends on your never always

level of experience 1 2 3 4 5 6 7 8 9 NA

Please write your comments about system capabilities here:

PART 8: User Manuals and On-line help

8.1 Technical manuals are confusing clear

1 2 3 4 5 6 7 8 9 NA

C-5

8.2 Information from the manual is never always

easily understood 1 2 3 4 5 6 7 8 9 NA

8.3 Amount of help given inadequate adequate

1 2 3 4 5 6 7 8 9 NA

Please write your comments about technical manuals and on-line help here:

PART 9: Software Installation

9.1 Speed of installation slow fast

1 2 3 4 5 6 7 8 9 NA

9.2 Customization difficult easy

1 2 3 4 5 6 7 8 9 NA

9.3 Informs you of its progress never always

1 2 3 4 5 6 7 8 9 NA

9.4 Gives a meaningful explanation never always

when failures occur 1 2 3 4 5 6 7 8 9 NA

Please write your comments about software installation here:

_______________________________________________________________________________________

ةــــــــــالصـخـال

الحقيقي السببتعد بداية قوية لمعرفة، مع اإلنسان مؤثرواجهة تخاطب دراسة إستراتيجية تفاعل

. األجهزة والمنتجات واإلعراض عن البعض اآلخروراء إقبال واقتناء المستهلك بعضالذي يكمن

في عدد الباحثين الحاسوب زيادة آبيرةأجهزة مستخدمي أعدادصاحب االتساع الكبير في

الحاسوب وشملت تلك البحوث وأجهزة اإلنسانالمتخصصين في دراسة موضوع التفاعل بين

.لهذا التفاعلة والنفسية والنظرية ئي الفيزيا اآلثاروالدراسات

آثير من المنتجات التي تحتاج إلى تفاعل بين المستخدم والمنتج أثناء استخدامها، لم يؤخذ بنظر

بل إنها صممت على أساس .اجات ومتطلبات المستخدم منذ المراحل األولى للتصميماالعتبار احتي

هدف هذه األطروحة هو إصالح ما تقدم عن إن . أنظمة تقوم بمجموعة معينة من الوظائف والمهام

أي تطوير ،في المراحل األولى للتصميم usabilityطريق إدخال مفهوم صالحية االستعمال

.المستخدمين وممتعه الستخدامها من منظور منتجات سهلة وفعالة

أعمدة يعتمد على ثالثة اإلنسان نجاح أي تصميم لواجهة التخاطب مع إن وجد األطروحةفي هذه

،اإلنسان البرمجية لواجهة التخاطب مع األدوات،للنهج العملي المتبعالتوجيهية الوثائق :رئيسية

تساعد مصمم واجهات " األعمدة الثالثة المذآورة آنفا . صالحية االستخدامواختبار الخبراء تنقيح

األعمدة آل عمود من إنأظهرت التجارب . التخاطب على تحويل األفكار الجيدة إلى نظم ناجحة

. ويسهل بناء أنظمة ممتازةاإلنسان لعملية تصميم واجهات التخاطب مع تعجيل قفزة يقدمالمذآورة

تم تطبيقها للسيطرة الرقابية واستخالص اإلنسانطب مؤثره مع واجهة تخا لتصميم ه المنهجيةهذ

المعلومات لمحطات عراقية لتوليد القدرة الكهربائية وقد تم اختبار هذا المنتج البرمجي عن طريق

ة البرمجياألداة المنتج باستعمالتم برمجة .ن مكتب القريشيم بيانات حقيقية مأخوذة إدخال

)SEMATIC Window Control Center (WinCC), version 6( بشرآة مصنع

Siemens-AG وواجهات التخاطب طرة الرقابية واستخالص المعلومات نظام السيأجزاء لتصميم

التجول والتتبع الذهني لمهام المنتج قيم هذا المنتج البرمجي بطرق وتقنيات مختلفة مثل . اإلنسانمع

Cognitive Walkthrough منافس أوالمقارنة مع منتج سابق واختبار الصالحية ب

Competitive Usability Testing و تم استخدام استبيان لمعرفة رضا المستخدمQUIS

. Quality Test تم اختبار الجودة للمنتج" أخيراو

وزارة التعليم العالي والبحث العلمي

الجامعة التكنولوجية

قسم هندسة الحاسبات ونظم المعلومات

إسرتاتيجية : ستخدمتصميم وتطبيق واجهة امل اإلنسانواجهة التخاطب مع تفاعل ل ةمؤثر

مقدمةطروحةأ المعلوماتتكنولوجيالقسم هندسة الحاسبات و

متطلبات الحصول على شهادة الماجستير في العلوم وهي جزء من

في اختصاص هندسة البرمجيات

إعداد الطالبة منى ضياء شيت خطاب

بأشراف محمد نجم عبد اهللا. د

2007آذار 1428ربيع األول