V&V Considerations In

Implementing IEC61508-3

Hanumath Managoli

Oak Systems Pvt Ltd.

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Agenda

Overview of Oak Systems

Overview of IEC61508-3, VnV

Q&A

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Overview of Oak Systems

Specialist Software V&V Services company

Established in 1998

ISO 9001 certified since 2003

Over 100 Software specialists

Multiple domain expertise

Headquartered in Bengaluru; Projects across

several countries

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Our Portfolio 4

Domains

Aerospace & Defence

Automotive

Embedded Healthcare

Rail & Space

Services

Software Verification &

Validation

Test Rig Development

Software Testing & Test Automation

Full lifecycle Documentation

Support

Standards

DO-178B/C

ISO 26262

IEEE 12207

IEC 61508..

IEC-615085

IEC-61508 – Safety Cycle6

IEC-61508 – Safety Cycle - Realization7

8Some terms & definitions

Safety This is freedom from unacceptable risk of physical injury or of

damage to the health of people, either directly, or indirectly

Functional safety is part of the overall safety that depends on a

system or equipment operating correctly in response to its inputs

Safety function requirements what the function does (from hazard

analysis)

Safety integrity requirements The likelihood of a safety function being

performed satisfactorily (from risk assessment)

9Safety Integrity Levels

SIL: Proportional to rigors of requirement

Derived at System level and assigned to Software/Hardware

Result of HAZOP, Risk Analysis

10While Developing…

• Requirements phase:

Structured representation

Formal methods, including mathematical representation

Semi-formal: Methods include truth-tables, decision tables,

information flow sequence charts, data flow diagrams,

states and modes transition diagrams listing the possible

states and the trigger events

Computer-aided documentation tools that include model

oriented representation

•

11While Developing…

• Design and development:

Structured design

Re-use of ‘proven-in-use’ components

Computer-aided design tool, including model-based methods and

simulation techniques

FMEA, Fault-tree analysis and corresponding Fault Detection, Isolation

and Recovery (FDIR)

Strongly typed programming language, proven tools like compilers

Auto-code generators

Defensive programming

Design, coding standards, guidelines and best practices

•

12Tools

• In-house, COTS, vendor, other (open-source)

• Classification:

on-the-fly

Off-line

• Qualification

13Software Verification

• Are there test cases to present events to system in random order

and random frequency and also at definite points of time and in

different and wrong sequences?

• Are there tests to check concurrency issues? (invoking different

interrupts at the same instance, invoking interrupts consecutively with

different order - different chains of interrupts, invoking different tasks

with different amount of resource availability)

14Software Verification

• Plan it out – in parallel with development

• Tools, Techniques and Strategies

• For each phase - Good to go for the next phase

• Results, deviations documented

• Verification of life-cycle artifacts; and testing

• Data verification

15Functional Safety Assessment

• Competent Personnel allocation

• Access to project-associate members and relevant resources

• Assessment applies to all phases and relevant artifacts

• Includes suppliers and their claims of compliance

• Covers FA audit reports

• Recommendations and resolutions from previous FA

• Report

• Level of independence

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Techniques and Measures

17T & M

• A: Normative: Selection of Techniques and Measures

• B: Informative – detailing (adding to A)

• C: Software Systematic Capability (adding to A, B)

18Software Aspects of System Safety

19Software Verification

20Software Verification

21Verification – TableC: Rigour & SIL

22Before Concluding

• Assessment

• Certification

• 61508 alone may not be enough – white goods, energy equip

UL1998 (in the US)

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Questions & Answers

hymanagoli@oaksys.net

Thank you!

Oak Systems Pvt. Ltd.#27, NGEF Lane, Off 100 Feet Road,

Indira Nagar, Bangalore – 560 038, INDIATel : +91-80-41 26 76 81

Email: contact@oaksys.net

URL: www.oaksys.net

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