Application Note for “Usage of AC500 digital standard I/Os in functional safety applications up to PL c (ISO 13849-1)”, V1.0.0
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Contents
1 Introduction _____________________________________________________ 3
1.1 Purpose ............................................................................................................................. 3
1.2 Document history ............................................................................................................... 4
1.3 Validity ............................................................................................................................... 4
1.4 Important user information .................................................................................................. 4
1.5 Definitions, expressions, abbreviations ............................................................................... 4
1.6 References / Related documents ........................................................................................ 5
2 Usage of digital standard I/Os in functional safety applications up to PL c _____ 6
2.1 Overview ............................................................................................................................ 6
2.2 Task ................................................................................................................................... 8
2.3 Solution .............................................................................................................................. 8
3 Example ______________________________________________________ 14
3.1 General ............................................................................................................................ 14
3.2 Safety function ................................................................................................................. 14
3.3 Functional description....................................................................................................... 15
3.4 Design features ................................................................................................................ 16
3.4.1 Implementation details 16
3.4.2 Common cause failures 18
3.4.3 Systematic failures 19
3.4.4 Safety function response time 20
3.5 Calculation of the probability of failure and correspondence to PL (ISO 13849-1) .............. 20
4 Conclusion _____________________________________________________ 23