SAMA diagrams

I currently work for a DCS manufacturer in their Application Engineering department. Our logic is implemented in the controller using SAMA diagrams instead of ladders or flow charts. Does anyone know of a PLC that can be programmed in SAMA? Also, has any of your customers ever asked for a SAMA representation of a program?

Regards,
Steve

Steve,

SAMA(Scientifica Apparatus Measurement Association) is a diagram which describes the control strategy and this is a pretty useful one for the programmers as this communicates to the programmer in much detal when compared to the ISA.

Whether it is a DCS program or PLC Ladder diagram or FBD, it does not matter and you can write the program (DCS or PLC).

Some customer's do insist on SAMA & it is reasonable.

Prasanna

prasanna said:

Whether it is a DCS program or PLC Ladder diagram or FBD, it does not matter and you can write the program (DCS or PLC).

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Prasanna:

It's possible to write ladder logic based off a SAMA drawing and vise-versa. But, typically the SAMAs are the "programming language" of the DCS in the same way that Ladder Logic is the programming language of many PLCs. Steve is probably posting this question because he is not comfortable with reading ladder logic.


Steve:

I don't know of any PLCs that use SAMAs. But you might try Allen-Bradley's ProcessLogix. This is supposed to be more of a DCS platform than it is PLC, though. Not having worked with it at all myself (but some others here have), I can't even tell you what the hardware looks like.

Out of curiousity, which DCS vendor are you with? I'm most familiar with Westinghouse, but I've had some dealings with Bailey and DeltaV as well.

AK

AS an FYI: SAMA is Scientific Apparatus Makers Association if I remember correctly

Ron's got it correct.
SAMA

Last year, I was involved with a project that used a Standard Automation and Control (http://www.standardautomation.com/) software package called ControlPlus which allows PLCs to be programmed using SAMA drawings. This was for a power plant in Wisconsin that uses on Modicon Quantum PLCs.

akreel said:

Steve is probably posting this question because he is not comfortable with reading ladder logic.
AK

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Akreel,

My post is actually about incorporating SAMA type algorithms into ladders. I am tired of copying the same 10 rungs for simple functions such as tracking, manual rejects, priorityt raise/lower, ect. I'm thinking of making my own SAMA type algorithms in PLC function blocks. I believe this will allow for a much quicker design and programming phase of a project. I'm not sure how in depth I want to go, but maybe create a SAMA library in RS Logix.

I'd like to hear opinions on this?

akreel said:

Out of curiousity, which DCS vendor are you with? I'm most familiar with Westinghouse, but I've had some dealings with Bailey and DeltaV as well.

AK

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I work at Westinghouse, mostly with the Ovation system, although I have done some WDPF stuff.

I will be glad to help with the Samba library code generation RLL logic. I am currently working on creating "pseudo" type functions for the AB SLC in subroutines, right now.

I just am not familiar with Samba. This, is actually my first time hearing it. I am comfortable with RLL, Function block diagram, structured text, and a little sequential function chart. I am interested in this Samba thing.

Is there anywhere to get information. Or can you provide examples, or explain. Is this similar to binary logic diagrams?

SteveG said:

I work at Westinghouse, mostly with the Ovation system, although I have done some WDPF stuff.

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We just sent a few guys to Pittsburgh for a FAT on an Ovation system for a power plant in the U.P. If you're working on that project, send me an e-mail and I might be able to help you out!

I think you're on the right track, by creating function blocks. Anything you can do to reduce the amount of cut-and-paste duplication of your ladder logic will cut programming time and should make reading the code easier. There really isn't any other "trick" I can think of, without actually knowing what your control program is supposed to do. But, that is probably way too much detail for this forum.

AK

If you want to program using function blocks, look at the IEC61131-3 certified programming packages. Function Block Diagram is one of the IEC languages.

The Concept package for Modicon controllers allows the use of function block only or a mix of function and ladder. Function block libraries can be created, saved, and reused in different applications. You can download a demo at http://www.modicon.com.