CENELEC 50128 and IEC 62279 Standards

CENELEC EN 50128 and IEC 62279 standards are applicable to the performance of software in the railway sector. The 2011 version of the 50128 standard firms up the techniques and methods to be implemented. This is a guide to its implementation, in order to understand the foundations of the standard and how it impacts on the activities to be undertaken, helping towards better a preparation for the independent evaluation phase, which is mandatory.

Auteur
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.

Contenu

INTRODUCTION xiii

CHAPTER 1. FROM THE SYSTEM TO THE SOFTWARE 1

1.1. Introduction 1

1.2. Command/control system 2

1.3. System 6

1.4. Software application 8

1.4.1. What is software? 8

1.4.2. Different types of software 9

1.4.3. The software application in its proper context 10

1.5. Conclusion 11

CHAPTER 2. RAILWAY STANDARDS 13

2.1. Introduction 13

2.2. Generic standards 14

2.2.1. Introduction 14

2.2.2. Safety levels 15

2.3. History between CENELEC and the IEC 16

2.4. CENELEC referential framework 17

2.4.1. Introduction 17

2.4.2. Description 18

2.4.3. Implementation 21

2.4.4. Software safety 22

2.4.5. Safety versus availability 22

2.5. EN 50155 standard 23

2.6. CENELEC 50128 26

2.6.1. Introduction 26

2.6.2. SSIL management 26

2.6.3. Comparison of 2001 and 2011 versions 28

2.7. Conclusion 30

CHAPTER 3. RISK AND SAFETY INTEGRITY LEVEL 31

3.1. Introduction 31

3.2. Basic definitions 31

3.3. Safety enforcement 37

3.3.1. What is safety? 37

3.3.2. Safety management 40

3.3.3. Safety integrity 47

3.3.4. Determination of the SIL 50

3.3.5. SIL table 55

3.3.6. Allocation of SILs 56

3.3.7. SIL management 57

3.3.8. Software SIL 58

3.3.9. Iterative process 59

3.3.10. Identification of safety requirements 60

3.4. In IEC 61508 and IEC 61511 61

3.4.1. Risk graph 62

3.4.2. LOPA 64

3.4.3. Overview 66

3.5. Conclusion 66

CHAPTER 4. SOFTWARE ASSURANCE 67

4.1. Introduction 67

4.2. Prerequisites 67

4.3. Quality assurance 68

4.3.1. Introduction 68

4.3.2. Quality assurance management 69

4.3.3. Realization of a software application 73

4.3.4. Software quality assurance plan (SQAP) 75

4.4. Organization 78

4.4.1. Typical organization 78

4.4.2. Skill management 80

4.5. Configuration management 82

4.6. Safety assurance management 84

4.7. Verification and validation 86

4.7.1. Introduction 86

4.7.2. Verification 87

4.7.3. Validation 103

4.8. Independent assessment 104

4.9. Tool qualification 104

4.10. Conclusion 105

4.11. Appendix A: list of quality documents to be produced 106

4.12. Appendix B: structure of a software quality assurance plan 106

CHAPTER 5. REQUIREMENTS MANAGEMENT 109

5.1. Introduction 109

5.2. Requirements acquisition phase 110

5.2.1. Introduction 110

5.2.2. Requirements elicitation 111

5.2.3. Process of analysis and documentation 119

5.2.4. Verification and validation of the requirements 126

5.3. Requirements specification 129

5.3.1. Requirements characterization 129

5.3.2. Characterization of requirements specification 135

5.3.3. Expression of requirements 135

5.3.4. Requirements validation 140

5.4. Requirements realization 140

5.4.1. Process 140

5.4.2. Verification 141

5.4.3. Traceability 143

5.4.4. Change management 146

5.5. Requirements management 150

5.5.1. Activities 150

5.5.2. Two approaches 151

5.5.3. Implementation of tools 152

5.6. Conclusion 154

CHAPTER 6. DATA PREPARATION 155

6.1. Introduction 155

6.2. Recap 156

6.3. Issue 156

6.4. Data-parameter-based system 158

6.4.1. Introduction 158

6.4.2. Characterization of data 161

6.4.3. Service inhibition 162 <...