About SFCs!!!

Hi everyone.. Great site u have here!!

This is my first post and i have a question, i hope it can be answered soon.

I just wanna know what is a (System Function)?? what's the purpose of it? and more important..

i work in a place with a Siemens s7 400 PLCs and there are alot of protected SFC and SFB in the system.. i just wanna know how to open them, not to edit or anything.. but i wanna know what's inside

Thanks in advance for your effort..
take care everyone, bye

M.Ragaey, Jr. HE Mech. Eng. EGYPT

A system function is built into the operating system inside the processor card and you cannot view the contents of these blocks using Simatic manager.

how can i open them?

Thanx buddy for the quick answer. i really appreciate it

but, now the question is.. is there anyother sofware to open these functions??

thnx bye

hello;

Runmode.com sells a software utility it calls S7canOpener that allows you to look at the content of a Know-How_Protected block.

Although if you are not familiar with STL programming, you will not understand the working of the blocks you open.... an exercice in futility for a beginner in Step 7 programming. No offense intended.
Hope this helps,
Daniel Chartier

Hi,
From Memory I think even with Canopener or equivilent you wont see whats in a SFC, only a Protected FC or FB will show any code.

Regards
Steve

Hi.. Stevo is right..
i tried the demo of can opener.. and he even dont see that there is an SFC.. all he saw is protected FC and FB

anyone has any idea.. pls post guys.. i need this answer urgently
thank u all

M.Ragaey

I'm afraid you just can't do it. I doubt that the code is even S7 based. These are part of the operating system.

If you need to dig into them, then you are looking at your problem the wrong way. I've used S7 since it came out, and the SFCs are the things that always work the way they are supposed to work. There just isn't a need to look at the underlying code.

Unregistered said:

Hi.. Stevo is right..
i tried the demo of can opener.. and he even dont see that there is an SFC.. all he saw is protected FC and FB

anyone has any idea.. pls post guys.. i need this answer urgently
thank u all

M.Ragaey

Click to expand...

I Know very little of S7 but i think the question that should be asked of "unregistered" is

Why do you want to access the plc's internal code ?

What exactly is your plc related probloem ?

Why do you want to access the plc's internal code ?

What exactly is your plc related probloem ?

Click to expand...

__________________

I suspect it's pure curiosity/interest, but in this case it's wasted effort.

maybe you can use Sequential FUnction

The reason Canopener or other methods can not view the contents of SFCs / SFBs offline is that they don't exist offline. In your offline project, you should find that the load memory for an SFC / SFB is always zero. Since they are inherent functions of the operating system in the CPU's ROM, all that gets stored offline is the call to the SFC/SFB, not the SFC/SFB itself.

And yes, I believe they are originally developed using standard languages like STL or SCL. Of course the output from the process then has to be translated down to the MC7 machine code for the S7 CPUs, but I suspect this is done automatically by a further compiler. No doubt this is kept safe in the Siemens vaults and never released to the outside world!

Regards

Ken