Certification Standards - Using Event-B for Critical Device Software Systems - page 306

IEC 61508 [ 9 , 12 ] as the fundamental standard for functional safety of the E/E/EP
systems [ 9 , 12 ]. The IEC 62304 [ 11 ] standard is for software life-cycles of med-
ical device development, which addresses to achieve more specific goals through
standard process activity. The process standard IEC 62304 [ 11 ] is a collection of
two other standards ISO 14791 and ISO 13485, where ISO 14791 standards are for
quality, and ISO 13485 is for risk management. Here, we have presented a brief
introduction about IEC 61508 and IEC 62304 standards, which may be achieved
using our proposed methodologies.

A.2.1 IEC 61508—Software Safety in E/E/EP Systems

Systems constitute of electrical and/or electronic elements, which can be used to
perform safety functions in many application sectors. ISO/IEC 61508 [ 9 , 12 ] con-
stitutes a generic approach for all safety life cycle activities of the electrical and/or
electronic and/or programmable electronic (E/E/PE) systems to perform safety func-
tions. It provides a generic development approach for achieving a rational and con-
sistent technical policy for all kinds of electrical systems to the safety-related sys-
tem. This standard provides some frameworks to consider safe and reliable for the
safety-related systems that are developed in other technologies. It covers a wide va-
riety of complexity, hazard and risk potentials related to the E/E/PE systems. Main
objective of this standard is to define a life-cycle for safety-critical software con-
sidering best practices and recommendations from early phases of requirements and
development to operation, maintenance and disposal. A complete detail description
about Software Architecture Design related to the properties for systematic integrity,
software design and development are given in a tabular form [ 9 , 10 , 12 ]. The main
objective of the IEC 61508 is to provide software architecture design, including
design activity of the system, which are defined as follows:

• Selection of techniques and verify the satisfiable level according to the safety

requirements

• Partitioning of the system

• Software/hardware interaction

• Unambiguous representation of the architecture

• Treatment of safety integrity of data

• Specification of architecture integration tests

Besides generic quality goals, the IEC 61508 also covers process dependen-
cies and concrete characteristics of the architecture related to the completeness and
correctness according to the requirements, no design faults, simple modular and
structure-able, satisfiable desired behaviour, verifiable and testable design, and fault
tolerance against system failure due to common cause [ 10 , 12 ].