[SystemSafety] COTS display certification

[Peter Bishop]

Matthew

You make a reasonable point about code / duality.

In principle, any input/output function could be implemented as a very
large lookup table. Most standard focus on getting the code right
(e.g. that the lookup code is correct). But what do standards have to
say about ensuring the data is correct? i.e. in my example, the data in
a massive look-up table? What data validation techniques are appropriate
to a given SIL?

Peter Bishop


On 27/07/2016 01:24, Matthew Squair wrote:
> I've always been a bit fuzzy about the next step though. 
> 
> If we decide that software will implement this function then the
> software development processes must satisfy the allocated integrity level. 
> 
> From a code/data duality perspective I implement a function in software
> as a mix of data and code. But I can use varying ratios of the two.
> Logically any integrity processes need to cover both the code and data
> 'parts' because it's both that are satisfying the functional requirement. 
> 
> But how does one argue equivalence between integrity processes for code
> and data? At the aggregate level surely you must be making that
> argument? And that such integrity is independent of potentially varying
> ratios of the two in any solution? 
> 
> Matthew Squair
> 
> MIEAust, CPEng
> Mob: +61 488770655
> Email; Mattsquair at gmail.com <mailto:Mattsquair at gmail.com>
> Web: http://criticaluncertainties.com
> 
> On 27 Jul 2016, at 3:21 AM, Peter Bernard Ladkin
> <ladkin at rvs.uni-bielefeld.de <mailto:ladkin at rvs.uni-bielefeld.de>> wrote:
> 
>>
>>
>> On 2016-07-26 18:33 , jean-louis Boulanger wrote:
>>> In new OCC system, some vital information are displayed on control
>>> screen and this informations is
>>> SIL x or DAL x.
>>
>> Sorry, such a statement is a category mistake.
>>
>> In IEC 61508, safety *functions* get SILs. Information is not a
>> function, therefore information
>> cannot get a SIL.
>>
>> PBL
>>
>> Prof. Peter Bernard Ladkin, Bielefeld, Germany
>> MoreInCommon
>> Je suis Charlie
>> Tel+msg +49 (0)521 880 7319  www.rvs-bi.de <http://www.rvs-bi.de>
>>
>>
>>
>>
>>
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> 
> 
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Peter Bishop
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