Siemens S7

F

Thread Starter

Frustrated

I have recently uploaded a program off of one of the S7s here and it of course has no decriptions in it. I am going through the program and editing the symbols, but I am not very familiar with siemens and though I have changed the the way most of the function block is displayed in the view menu. there are still certain Networks that do not seem to change.

Help?????
 
Yes! This how it works. I had a similar problem. If program is written in STL, some rungs may not get converted to ladder.

You need to add NOP "No operation" instructions in the logic. A detailed explination is given in S7 Ladder manual.

It’s tough no doubt.
 
S
In siemens PLCs we have 3 basic languages: Ladder (LAD), Function Block Diagram (FBD) and Statement List (STL). If the programmer has programmed the PLC in STL it cannot be changed into LAD or FBD, and S7 also have some functions which can only be programmed in STL (it is the core language for Siemens PLC). A program initially written in LAD or FBD can be changed completely in any of three languages. If you have any more difficulty feel free to contact at [email protected]
 
In Siemens S7 plc programming, all ladder and FBDs can be transformed to STL.

Unfortunately, not all STL can be transformed to either ladder or FBD.
 
You can view all networks in STL, but you can only view those in ladder which have been written in ladder in the first place (or follow a very strict form, that is nowhere described).
 
Some Networks may be written in STL and in this case it is impossible to to display them in LAD or FBD view.
 
I think the moderator from this website picked a wrong title for your problem and everybody "took the bite". The way you describe the problem, it is NOT about statement list to ladder conversion! I think you did not have the offline block (OB, FB or FC) that you tried to open/edit. And, you just uploaded from the PLC. In this case everything is very messy. Of course there are no descriptions (because they are not downloaded in the PLC) and all static and temp declarations lost their original names looking like: STAT_0, STAT_10, etc. If this is what happened, nobody can help you, except your equipment supplier. Ask them for the "archived S7 project". Once you have it, you will be able to see a much nicer code (it doesn’t matter what was the original language: STL, LAD, SCL, FBD, etc).

If I was wrong, and you really have a STL to LAD conversion problem, send me the "awl" file at [email protected] If it’s not very long I might be able to help you.

Since you are not familiar with Siemens PLCs I will explain how to create the "awl" file:
- From S7 manager open a block (it doesn't matter which one).
- Once you are in the LAD/STL/FBD editor click "File/Generate Source" (Ctrl+T)
- Give it a name (in the small window that just opened) and hit OK.
- In the new window select your problem subroutine and add it to the right side. Note: In the lower right corner select "Absolute" for addresses. Hit OK.
- Now, go back to S7 manager and select "Sources" in the left window. (above blocks)
- Find the source file with the name you previously selected, right click and select "export source". Go with the default name and put it somewhere to remember.
- Email me this file (it is not more than few kb).

But I still think you don’t have the PLC program (offline) and you will need to contact your equipment vendor.

ValRo
 
Hi;

i want to ask a question a bit related with this topic. i am studying s7200 on my own nowadays. i learn that s7200 program works on stacks. (operating principle)

here is a simple s7200 plc program.

LD I0.0
LD C0
CTU C0,2
CTU C1,1
LD C1
= Q0.0

can anyone tell me the conditions of I0.0 C0 C1 and Q0.0 at every scan of the program?

1st scan: I0.0 :
C0 :
C1 :
Q0.0 : ....

thank u...
 
M

marc sinclair

Sedat,

The answer is:

I0.0 - OFF
C0 - OFF (Value 0)
C1 - OFF (Value 0)
Q0.0 - OFF

and of course, they stay this way forever.

I don't think that really helps you, does it? Can you let us know what you are trying to do? Perhaps learning on your own is not the way.

Might I suggest that you download the primers and introduction literature from the Siemens website - the documentation is excellent, also try downloading the trial software, and some 'tips and tricks' examples, study the code, you can convert ladder or FBD to STL if you must, although you cannot use IEC1131 mode.

Then try writing a small application which turns one of the outputs on and off, once a second - let us know how you get on.

--
Marc Sinclair
http://www.germainesystems.co.uk
 
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