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Some key changes in edition 2
Terms, definitions and abbreviations
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More closely aligned with IEC 61508
Edition 2 is Based on IEC 61508 route 2H
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Hardware fault tolerance defined by table 6 (no Safe Failure Fraction)
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Route 1H can be used by going to IEC 61508
Systematic Capability
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Largely built into requirements.
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Components / elements assessed in accordance with IEC 61508 must be used in accordance with IEC 61508 Systematic Capability
requirements.
BPCS as a protection layer
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Clarification has been added regarding the number of BPCS independent protection layers that can be used for a given hazard.
Software
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Some parts of edition 1 section 12 have been distributed to the appropriate lifecycle clauses.
Security
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Clauses for security have been added.
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This a specialist subject in it’s own right, so the standard points to other standards for detailed guidance.