Applying Failure Mode Modular De-Composition (FMMD) across the software/hardware interface

This paper presents a modular variant of Failure Mode Effects Analysis (FMEA), Failure Mode Modular De-Composition (FMMD), a methodology which can be applied to software, and is compatible and integrable with FMMD performed on mechanical and electronic systems. Software generally sits on top of most modern safety critical control systems and defines its most important system wide behaviour and communications. Currently standards that demand FMEA for hardware (e.g. EN298, EN61508), do not specify it for software, but instead specify good practise, review processes and language feature constraints. This is a weakness. Where FMEA traces component failure modes to resultant system failures, software has been left in a non-analytical limbo of best practises and constraints. If software and hardware integrated FMEA were possible, electro-mechanical-software hybrids could be modelled, and so we could consider `complete´ failure mode models. Presently FMEA, stops at the glass ceiling of the computer program: FMMD seeks to address this, and offers additional test efficiency benefits.