SCL in S7

userxyz · Feb 7, 2007

Hi,

I write mostly in STL now, before a year ago I was a ladder man.

@ school I've learned VHDL (higher programminglanguage looking like SCL)

I have no experience in SCL...

When it's better to use SCL instead of STL ?
Can you monitor in SCL like in STL ?
Anyone has a good tutorial ?

Thanks in forward,

Regards,

Gerry

L D[AR2P#0.0] · Feb 7, 2007

SCL - ideal for multi-dimension array processing. Online monitoring shows values in variables as lines of SCL are processed.

bebecall · Feb 7, 2007

I'm a STL guy now after learn the way of manupilating DBs and ARs registers which other languages is not able to provide. It also take time to understand the limitation of changing the content of this registers under different situation of FB and FC calls.

SCL is very much similar to C or Pascal. Its a great tool with implementing PID control or matrix handling. But end of day, the SCL editor will convert the compiled codes into STL. To view it in SCL code in STL, please don't double click from Simatic Manager, simply just open it from LAD/STL/FBD editor.

Cheer,
^^

Ken M · Feb 7, 2007

the SCL editor will convert the compiled codes into STL

Is this actually correct? I've always had a belief that the the SCL compiler behaves exactly the same as the STL compiler and the S7-Graph compiler etc. They all produce blocks of 'nearly' executable object code which is finally recompiled in the PLC CPU down to machine language. I don't know what form the object code is in (MC7?) but it so happens that the only editor capable of reading these object code blocks regardless of the compiler used to create them is the STL editor. Just because you can view the de-compiled block content using STL doesn't mean it's STL code that's in the block. Or can someone prove that SCL and others do genuinely generate STL instructions? If so, why don't they use better ones!?

Regards

Ken

PeterW · Feb 7, 2007

Ken M said:
I don't know what form the object code is in (MC7?)

It is STL, in fact basic without the interface would be numbers that represent the STL. But STL is the very basic form of Siemens code.

SCL, Ladder, Graph7, etc all break down to STL.

L D[AR2P#0.0] · Feb 7, 2007

Here's some "STL" compiled from an SCL block. As you can see, function calls are shown in their basic form as the STL editor does not show them in the nice CALL format you get if the block was created using the block editor. If you try and edit the block and change the parameters to FC193, the STL editor will not let you.

L DIB [AR1,P#762.0]
T LB 14
TAR2 LD 34
TAK
T LD 16
TAK
UC FC 193
P#L 0.3
P#L 13.0
P#L 0.5
P#L 14.0
LAR2 LD 34
A #bLeftFaultDetected
L LB 14
LAR1 LD 16
T DIB [AR1,P#762.0]

userxyz · Feb 8, 2007

So

So, any tutorials ?

Or lets say that I want to see this in SCL (it's a start that I need):

A I0.0
X I0.1
= Q0.5

A Q0.5
JCN STP

L 50
T SETP

STP: L 0
T SETP

Peter Nachtwey · Feb 8, 2007

Your program is flawed.

SETP will always be set to 0.

Code:

   Q0.5:=I0.0 xor I0.1;
   if Q0.5 then
	  SETP:=50;
   end
   SETP:=0;

STL??? · Feb 8, 2007



        A I0.0

        X I0.1

        = Q0.5

    

        A Q0.5

        Jcn Stp

    

        L 50

        JU Send

    

   Stp: L 0

  Send:t Setp

dchartier · Feb 8, 2007

Which modifies Peter's code to:

Q0.5:=I0.0 xor I0.1;
If Q0.5 then
SETP:=50;
Else
SETP:=0;

Ken M · Feb 8, 2007

Help me here.
Doesn't L D[AR2,P#0.0]'s example in Post 6 tend to suggest that SCL does not compile to STL? If it did, why wouldn't a simple FC call operation be compiled as the direct STL equivalent CALL? Isn't this indicative that the SCL is in fact compiling to some other code form? And then when you use the STL editor/viewer it's making the best sense of it that it can. And the fact that you can't edit it would also support the theory that the block contents aren't truly STL?

There's another forum I contribute to where one of the regulars has a sign-off "It's not an optical illusion, it just looks like one." I'm starting to feel the same about this issue!

Ken

JesperMP · Feb 8, 2007

Ken M said:
And the fact that you can't edit it would also support the theory that the block contents aren't truly STL?

I think that the Property "Created in SCL language" causes edits in the LAD/STL/FBD editor to be inhibited. This probably to avoid inadvertently goofing up the SCL code. But you can allways copy-and-paste from the STL view of the SCL code to another block with STL.

And I think that the "basis" code language in S7 is always STL.
STL is like assembly language, and MC7 is like machine code.

L D[AR2P#0.0] · Feb 8, 2007

Ken - from the evidence that I've seen, there is no such thing as a CALL (so to speak) in STL, all calls are actually performed as CC or UC. The STL block editor embeds control codes into the block so that when it is displayed, it is shown as a call with a list of parameters.

Here's some STL in "normal" block editor display (a simple call):

CALL FC 5
IN0 :=L#5
RET_VAL:="dbDataq".DataW
NOP 0

And here is the same code after removing all knowledge of FC5 from the editor:

Call
BLD 1
= L 72.0
L L#5
T LD 73
L 1
T LW 77
L P#DBX 0.0
T LD 79
UC FC 5
P#L 73.0
P#L 77.0
BLD 2
End Call
NOP 0

Ken M · Feb 8, 2007

Oh. I get the feeling I should have stopped asking questions slightly earlier.

I'll stick to LAD wherever possible now!!

Ken

userxyz · Feb 9, 2007

lad vs stl

In my opinion: LAD makes u a much slower programmer

SCL in S7

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