Safety Management for Software-based Equipment

A review of the principles of the safety of software-based equipment, this book begins by presenting the definition principles of safety objectives. It then moves on to show how it is possible to define a safety architecture (including redundancy, diversification, error-detection techniques) on the basis of safety objectives and how to identify objectives related to software programs. From software objectives, the authors present the different safety techniques (fault detection, redundancy and quality control). ?Certifiable system? aspects are taken into account throughout the book.

Contents

1. Safety Management.
2. From System to Software.
3. Certifiable Systems.
4. Risk and Safety Levels.
5. Principles of Hardware Safety.
6. Principles of Software Safety.
7. Certification.

About the Authors

Jean-Louis Boulanger is currently an Independent Safety Assessor (ISA) in the railway domain focusing on software elements. He is a specialist in the software engineering domain (requirement engineering, semi-formal and formal method, proof and model-checking). He also works as an expert for the French notified body CERTIFER in the field of certification of safety critical railway applications based on software (ERTMS, SCADA, automatic subway, etc.). His research interests include requirements, software verification and validation, traceability and RAMS with a special focus on SAFETY.

INTRODUCTION ix

CHAPTER 1. SAFETY MANAGEMENT 1

1.1. Introduction 1

1.2. Dependability 1

1.3. Conclusion 8

1.4. Bibliography 8

CHAPTER 2. FROM SYSTEM TO SOFTWARE 9

2.1. Introduction 9

2.2. Systems of command and control 10

2.3 System 13

2.4 Software implementation 14

2.5. Conclusion 16

2.6. Bibliography 17

2.7. Glossary 17

CHAPTER 3. CERTIFIABLE SYSTEMS 19

3.1. Introduction 19

3.2. Normative context 20

3.3. Conclusion 37

3.4. Bibliography 38

3.5. Glossary 41

CHAPTER 4. RISK AND SAFETY LEVELS 43

4.1. Introduction 43

4.2. Basic definitions 43

4.3. Safety implementation 48

4.4. In standards IEC 61508 and IEC 61511 70

4.5. Conclusions 74

4.6. Bibliography 74

4.7. Acronyms 77

CHAPTER 5. PRINCIPLES OF HARDWARE SAFETY 79

5.1. Introduction 79

5.2. Safe and/or available hardware 79

5.3. Reset of a processing unit 80

5.4. Presentation of safety control techniques 81

5.5. Conclusion 117

5.6. Bibliography 118

5.7. Glossary 119

CHAPTER 6. PRINCIPLES OF SOFTWARE SAFETY 121

6.1. Introduction 121

6.2. Techniques to make software application safe 121

6.3. Other forms of diversification 149

6.4. Overall summary 150

6.5. Quality management 150

6.6. Conclusion 155

6.7. Bibliography 156

6.8. Glossary 157

CHAPTER 7. CERTIFICATION 159

7.1. Introduction 159

7.2. Independent assessment 159

7.3. Certification 160

7.4. Certification in the rail sector 161

7.5. Automatic systems 171

7.6. Aircraft 171

7.7. Nuclear 171

7.8. Automotive 172

7.9. Spacecraft 172

7.10 Safety case 172

7.11 Conclusion 173

7.12 Bibliography 174

7.13 Glossary 176

CONCLUSION 177

INDEX  179

Jean-Louis Boulanger is currently an Independent Safety Assessor (ISA) in the railway sector focusing on software elements. He is a specialist in the field of software engineering (requirement engineering, semi-formal and formal method, proof and model-checking). He also works as an expert for the French notified body CERTIFER in the field of certification of safety critical railway applications based on software (ERTMS, SCADA, automatic subway etc.). His research interests include requirements, software verification and validation, traceability and RAMS with a special focus on SAFETY.