Re: [SystemSafety] SIL 4 and IEC 61131-3 languages

From: Daniel Grivicic < >
Date: Sun, 20 Mar 2016 07:12:39 +1100

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?

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.


On Sun, Mar 20, 2016 at 2:50 AM, jean-louis Boulanger < jean.louis.boulanger_at_xxxxxx

> 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
> in french).
> 2016-03-18 13:58 GMT+01:00 Daniel Grivicic <grivsta_at_xxxxxx >
>> 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_xxxxxx >>
>>> 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_xxxxxx >>>
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