Safety-related control systems systematic faults

There is possibility of confusion regarding use of two standards viz ISO 13489. lEC 62061. Normally when medium other than electrical system, ISO 13489 may be more appropriate. Whereas for customer demand for demonstrating safety lEC 62061 may appropriate. Fot safety-related control systems, standard components can be used as it is allowed as pet standard also. However, safety components offer the advantage of reducing workload as the safety-oriented assessment, and analysis of the components used, is carried out by the producer of the safety components. For functional safety, the systematic integrity of components is taken into account, in addition to the use of a suitable category, the implementation of necessary fault detection and the... 

AU other possible failure impacts by the microcontroller to the application software need to already be controlled by the basic software. However, it is a question of preferred software architecture, where the error types are safeguarded. It would be possible that the errors are controlled in the basic software. Especially data correction, control mechanism or implemented safely mechanism versus systematic errors from the peripheral, sensors and also from the microcontroller itself effectively implemented in the basic software would simpUfy the application software and related safety mechanism. If possibly the application software needs only safety mechanism against their own systematic faults or safely mechanism which are implemented in software but control the systematic failure on system level could simplify the needed architecture and related dataflow tremendously. Since safety goals are often also subjects to change, the safely mechanisms against systematic failures on system level should be implemented in an independent area. 

Software hazard analysis (SWHA) is a system safety analytical technique whose primary function is to systematically evaluate any potential faults in operating system and applications software requirements, codes, and programs as they may affect overall system operation. The purpose of the SWHA is to ensure that safety specifications and related operational requirements are accurately and consistently translated into computer software programs. In this regard, the analysis will verify that specific operational safety criteria, such as failsafe or fail-passive, have been properly assimilated into operational software. The SWHA will also identify and analyze those computer software programs, routines, or functions that may have direct control over or indirect influence on the safe operation of a given system. Also, in the operation of the computer software command function, there is a potential that the actual coded software may cause identified hazardous conditions to occur or inhibit a desired function, thereby creating additional hazard potential. 

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