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RAF_Blackace
2010-Feb-19, 07:19 PM
If this is in the wrong forum please fell free to move it elsewhere, but as there is no other forum where I could ask this then I thought I had better put it here.

I am sure (hope) there are some software engineers who may wish to comment on this question.

Prior to this standard, there was the widely used IEC 61131. This clearly defined to programmers, certain coding standards. These standards were used to develop programming tools. These tools ensured that certain standards were adopted industry wide and almost all of us could understand what was going on and each others code.

Now we have the new standard IEC 61499.

It clearly states..."surprisingly the primary purpose of IEC 61499 is not as a programming methodology but as an architecture and model for distributed systems".

"There is no intention that the standard, as defined, will be used directly by programming tools".

"IEC 61499 provides terminology, models and concepts to allow the implementation of a function block oriented distributed control system to be described in an unambiguous and formal manner".

So, we have gone from a well known standard that clearly defined our work (so much so that we could instantly understand what each of us were trying to do just by looking at each others code). To a standard that allows us to stand around in bars and talk to each other, but means our software is not defined in any way shape or form.

Isn't this a step backwards and not forwards ?

Does anyone know what EN 61499 is trying to do, or was it just an excuse for some guys to claim expenses for several years and live the high life ?

HenrikOlsen
2010-Feb-19, 09:17 PM
From the immediate descriptions, it looks like they cover different levels of abstraction, with EN/IEC 61499 looking at a system as blackboxes with defined behavior and interfaces for intercommunication, and EN/IEC 61131 defining methodology for implementing them, but I could well be completely wrong as I don't work with either.

RAF_Blackace
2010-Feb-19, 10:12 PM
Well that is what is strange, 61131 defines the logical implementation, 61499 seems to only define architecture or the communication interfaces between them.

But this is supposed to be the replacement standard for 61131. That is what is so confusing.

We might as well just ignore both now because apparently we now have no standard to define the logical layer.

HenrikOlsen
2010-Feb-19, 10:37 PM
To me they look supplementary but if it's clearly indicated that one's a replacement for the other, then I think someone grabbed the wrong herb to smoke.

Jim Christensen
2010-Feb-20, 01:52 AM
IEC 61499 is an architecture for encapsulation and reuse of algorithms written in the IEC 61131-3 languages, as well as other languages such as Java and C++, and their deployment in distributed, event-driven systems rather than the centralized, scanned systems for which the 61131-3 languages were originally developed. This is already supported by a number of software tools, many of which are freely available and some of which are open source. For an introduction, see http://knol.google.com/k/james-christensen/iec-61499/. Happy reading!

RAF_Blackace
2010-Feb-20, 04:13 AM
IEC 61499 is an architecture for encapsulation and reuse of algorithms written in the IEC 61131-3 languages, as well as other languages such as Java and C++, and their deployment in distributed, event-driven systems rather than the centralized, scanned systems for which the 61131-3 languages were originally developed. This is already supported by a number of software tools, many of which are freely available and some of which are open source. For an introduction, see http://knol.google.com/k/james-christensen/iec-61499/. Happy reading!

Jim, from what you know can you elaborate. It seems to me that 61499 is solely for distributed systems and it does not bring into the fold higher level systems written in Object Orientated (OO) code. In fact it seems to ignore them completely.

Just what does it bring to the table ?

Thanks for the links, I have been tasked with assessing the standard to make sure we are compliant, your links are very useful resources.

James.... Are you the Chairman ? I am reading the book by Robert Lewis and he credits you in the preface.

RAF_Blackace
2010-Feb-20, 04:41 AM
James, it seems you are the Chairman. Thank you very much for the link. I have a few books and the standards to get through but was struggling to understand how it applies to lower level systems. Your links are so well written it makes it a lot easier to understand.

Hope you enjoyed the expenses. :)

http://newworldodor.files.wordpress.com/2009/09/egg-on-face1.jpg

peteshimmon
2010-Feb-20, 06:11 PM
Just shows, you dont know who reads these pages
do you.

Google may have helped!

Jim Christensen
2010-Feb-20, 07:07 PM
Just shows, you dont know who reads these pages do you. Google may have helped!
Yes, I've got Google Alerts set to catch all references to IEC 61499. Amazingly, it found this thread the very same day!

Cheers,
Jim Christensen

Jim Christensen
2010-Feb-20, 07:14 PM
...I have been tasked with assessing the standard to make sure we are compliant, your links are very useful resources.
Do be careful about compliance. Any statement of compliance from a vendor is incomplete unless it references a Compliance Profile as defined in 61499-4. Otherwise you have no idea whether and how the product meets the 61499 goals of portability, interoperability and configurability. Rather like the situation with 61131-3 before PLCopen did their work. At least 61499 gives some idea about what should be in a profile; PLCopen had to do theirs from scratch.

Best regards,
Jim C

HenrikOlsen
2010-Feb-20, 07:25 PM
Yes, I've got Google Alerts set to catch all references to IEC 61499. Amazingly, it found this thread the very same day!
This forum is crawled very aggressively by Google and the other search engines, of the 480 guests we has in the last hour I'd guess 450 were search engine spiders.

RAF_Blackace
2010-Feb-20, 08:30 PM
Do be careful about compliance. Any statement of compliance from a vendor is incomplete unless it references a Compliance Profile as defined in 61499-4. Otherwise you have no idea whether and how the product meets the 61499 goals of portability, interoperability and configurability. Rather like the situation with 61131-3 before PLCopen did their work. At least 61499 gives some idea about what should be in a profile; PLCopen had to do theirs from scratch.

Best regards,
Jim C

That is very useful information, thanks for this Jim.

Here is me reading a book and asking for some clarifications and the guy who wrote the preface for the book, and is the chairman of the IEC65/WG8 working group that wrote the standards replies.

I love the internet sometimes.