statement list training

Shilo · Mar 22, 2006

I have a good understanding of ladder logic but get completely lost trying to read statement lists. Where can I get good training on Step 7 statement list usage. I bought a book but need human instruction on this one.

PLucas · Mar 22, 2006

Shilo said:
I bought a book but need human instruction on this one.

What book did you buy? Was it the one by Hans Berger? That is the best one to get.

One way of understanding STL is to write some logic in LAD then use Step 7 to convert it to STL for you. This would be better if you could do this on line in a PLC.

Paul

geniusintraining · Mar 22, 2006

Shilo,

I see that you are in Georiga, Siemens classes in Atlanta, you can get a lot from them also Paul (PLucas) gave me a link to a Siemens site here try Appendix III at the bottom of the page, in it there are many if not all comparisons from ladder, block and STL its good.

Shilo · Mar 22, 2006

Yes, it was Berger's book. I think I need STL for Dummies.
I have written a little and converted it, but there are commands used in the program I have to occasionnally troubleshoot that don't necessarily have ladder equivalents.

STL??? · Mar 22, 2006

but there are commands used in the program I have to occasionnally troubleshoot that don't necessarily have ladder equivalents

In the STL/LAD/FBD Editor,Place the cursor on the command and then press F1 to call the help page for that instruction,along with an example.

Hope this helps

PLucas · Mar 22, 2006

Shilo said:
I think I need STL for Dummies.

I don't think there is one!

Shilo said:
there are commands used in the program I have to occasionnally troubleshoot that don't necessarily have ladder equivalents

That is true, but if you know what the menomics stand for you should be able to work out what they do, using your knowledge of LAD, if you still don't understand, post them on this forum and someone will know what they do and will be able to explain it to you.

If it's any consolation, I have had to work with and in STL for a while now and I still avoid it as much as possible, when I work in S5, most of the 'stuff' I write is in STL, but in S7 the vast majority of what I want to do is available in LAD.

Paul

P.S The Berger book is by far the best book you can have, the vast majority of us who use S7 have this book. You could call it the S7 bible

P.P.S I see that STL??? posted while I was typing this reply, use the tip that he has given as well

Shilo · Mar 22, 2006

Thanks for all the replies. I'll work on it tonight.

Automatiker · Mar 23, 2006

Shilo said:
I have a good understanding of ladder logic but get completely lost trying to read statement lists. Where can I get good training on Step 7 statement list usage. I bought a book but need human instruction on this one.

And I have exactly opposite problem, I can very easily read and program in STL and I cannot program in LD, what is more worse I don't understand whatfor is LD and why schould I program in LD when I can do this in STL. I would be greateful if someone would tell me the advantage in programmin in LD.

Johnny T · Mar 23, 2006

Several reasons for programming in Ladder, most of them revolve around making it easy to fault find and modify for your average electrical/PLC guy. It is much easier to 'read' for most of the folk who have started with an electical background and moved over to PLC's as it is very similar to an electrical drawing.

The vast majority of people prefer ladder and I know of customers who insist that when contractors write software for them, they use as much ladder as possible (ie. only using STL for pointers etc).

But.. I suppose, at the end of the day, its about preference. Myself.. I much prefer ladder. ;-)

jstolaruk · Mar 23, 2006

Johnny T said:
Several reasons for programming in Ladder, most of them revolve around making it easy to fault find and modify for your average electrical/PLC guy. It is much easier to 'read' for most of the folk who have started with an electical background and moved over to PLC's as it is very similar to an electrical drawing.

The vast majority of people prefer ladder and I know of customers who insist that when contractors write software for them, they use as much ladder as possible (ie. only using STL for pointers etc).

But.. I suppose, at the end of the day, its about preference. Myself.. I much prefer ladder. ;-)

Bingo! A debugging electrician only has to glance at a ladder rung and can instantly visualize whats happening. I have one customer whose one plant is all Siemens and their spec says STL is fine but it must convert to LD for that very reason.

Automatiker · Mar 23, 2006

Ok, I agree, maybe it is more clear to see what happens in small application. And what if you have 100 FC with 30 Networks?

jstolaruk · Mar 23, 2006

Small or large application, the reason for that customer (and me) is the same. LD, being a visual method, is read easliy by the folks that are not programming gurus (that includes my boss!).

Anytime I can make it easier for the customer, I'll tend toward it. It usually means one or more less phone calls.

Automatiker · Mar 23, 2006

As I assume you stay in USA. I am in Germany and in a school I was told that it is much more important to know STL because LD is like a toy to play and not to program. The teacher was from siemens

. Maybe somebody from Germany can write something more...

jvdcande · Mar 23, 2006

The teacher was from siemens.

Figures. STL is Siemens only. If you go to another brand you'll see the statements are different from the Siemens statements. In fact, each and every manufacturer has his own statement list version. Ladder diagramming on the other hand is pretty much the same for all or most brands. So, by urging people to use their, and only their, instruction set, they try to protect their market share.

Another reason I have heard for using STL is that it looks smarter. Well, in my view, the smartest programmer is the one who can avoid being called out of bed in the middle of the night to service a machine.

Kind regards,

Automatiker · Mar 23, 2006

So, by urging people to use their, and only their, instruction set, they try to protect their market share.

Now I understand. I knew that something was wrong with this teacher

.

If you go to another brand you'll see the statements are different from the Siemens statements

Maybe it is the problem of the german market. Not many people use here other PLCs then Siemens' PLCs.

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