[SystemSafety] SIL 4 and IEC 61131-3 languages

[Daniel Grivicic]

Hi Jean-Louis,

You are correct; it depends on your domain. The same controller I have used
that is suitable for use in SIL3 within a process control domain, is also
certified for use SIL4 within CENELEC in rail. It is programmed using an
IEC61131-3 language. I forgot about the SIL4 capability because my domain
is typically different. One unfortunate aspect of this domain specificity
is that the device will be marketed by sales people as SIL4 but not outline
the domain or the significant restrictions required to meet requirements
for use.

Could this be another reason why the concept of SIL is broken?

http://criticaluncertainties.com/2015/11/16/why-iec-61508s-sil-concept-doesnt-work/

Thank you for the reference, security is an emerging area at the moment
where (in hindsight) it should have been properly considered many years ago.

Daniel.



On Sun, Mar 20, 2016 at 2:50 AM, jean-louis Boulanger <
jean.louis.boulanger at gmail.com> wrote:

> actually du to the table of technics in 61508, many PLC are certified SIL3
> but if you analyze the technics table you can see that to achieve a SIL4
> you need to double the cost (from SIL3).
>
> I put in service in railway domain some PLC  with CENELEC-SIL3 or
> CENELEC-SIL4 objective. we used some certified PLC and proprietary language
> (SIEMENS/ROCKWELL/..) and we need to add extra rules and tools for
> metrics:programming rules/testing ....
>
>
> additionally, you need to know that the ANSSI introduced new rules request
> for PLC (see
> http://www.ssi.gouv.fr/guide/la-cybersecurite-des-systemes-industriels/
> in french).
>
> 2016-03-18 13:58 GMT+01:00 Daniel Grivicic <grivsta at gmail.com>:
>
>> Dear Bertrand,
>>
>> If you assume that the devices which use IEC61131-3 are typical of the
>> industry, then you will find that SIL3 is possible and widely found however
>> SIL4 is not. I am not aware of any PLC that is capable of SIL4 and is
>> software configurable. The 3 such devices I am aware of use logic cards and
>> are hard wired.
>>
>> Sorry I cannot assist much more.
>>
>> Thanks
>>
>> Daniel.
>>
>> On Thu, Mar 17, 2016 at 11:30 PM, RICQUE Bertrand (SAGEM DEFENSE
>> SECURITE) <bertrand.ricque at sagem.com> wrote:
>>
>>> Given the experience and knowledge existing on assessing SIL 4 or DAL A
>>> systems based on ADA or C++, do you estimate that the same result
>>> (compliance) is achievable with the IEC61131-3 proprietary languages ?
>>>
>>> Same question for SIL 3 / DAL B.
>>>
>>> Thank you,
>>>
>>> Bertrand Ricque
>>> Program Manager
>>> Optronics and Defence Division
>>> Sights Program
>>> Mob : +33 6 87 47 84 64
>>> Tel : +33 1 58 11 96 82
>>> Bertrand.ricque at sagem.com
>>>
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>
>
> --
> Mr Jean-louis Boulanger
>
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