Self-diagnostic function

Operational qualification, or acceptance testing, is the process of demonstrating that the whole instmment or its modules will function according to its operational specification, in the selected environment, according to previously defined functional and performance specifications ( acceptance criteria ). This procedure can be performed to the extent of the self-diagnostics routine test or to a more detailed procedure regarding flow-rate, injector precision, or wavelength accuracy. It can be carried out by the user or the vendor on behalf of the user. 

The overall SIS architecture may impose additional functional software requirements to the specified safety instrumented functions. A typical example is the 1oo2 selection logic for redundant sensors as well as a specified safe action on detection of a dangerous failure by sensor self-diagnostics. Examples given in Annex B list those requirements originated from the applied architecture. 

The self-diagnostic capability of a safety instrumented function is a critical variable for safety integrity verification. Good diagnostics improve both safety and availability. Detection of component failures is done by two different techniques classified as reference or comparison. 

As in most instrumentation, process analyzers have undergone a fundamental change from hard-wired controllers, switches, and rotary knobs to microprocessor-based software control. With microprocessor control, more advanced functions have become available. Recent years have seen a trend in the incorporation of self-diagnostic routines in the instrument. 

Maintainable - supporting robust plant floor operation (maximum up time), expeditious repair (minimal downtime), and easy maintenance (extensive support from controller suppliers, small spare part inventory, integrated self-diagnostic and help functions, etc.). 

RDM Self-diagnostics and redundancy management of functional subunits... 

The Diagnostic and Statistical Manual of Mental Disorders lists several distinct criteria necessary for a diagnosis of schizophrenia.5 These criteria include a marked disturbance in the thought process, which may include bizarre delusions and auditory hallucinations (i.e., hearing voices ). Also, a decreased level of function in work, social relations, and self-care may be present. Other factors include the duration of these and additional symptoms (at least 6 months) and a differential diagnosis from other forms of mental illness (such as affective disorders and organic brain syndrome). 

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