siemens programming.

Hi everyone,

I just get a 3 days curse of siemens PLC's (S7-300), and I see for the first time what people talks when they refer to FC, FB, and so on. I must admit, I don't get it 100%, must use it a little I think.

But, what I also see, is the SCL, and I can say, that for someone like me, that spent more years in normal programming than ladder, (including TPascal & Delphi), it seems really nice, and give another agility to the programming. (Or so it seems in now).

My question is, for the people that already works with Siemens, how they make the combination using the diferent programming languages, or if they use only one. When I refer to the combination, is to know if there are some tasks that are more easily programmed in one or other way, or you just use one language for all.

Also, I want to ask how good is the compiler of the SCL, that is to say, how are the cyclic time for the same rutine, made with SCL or Ladder.

And for last, if you have some adivise to share... mostly, becasuse up what they told me, my next project will be with Siemens. And I will have to make it with S88

thanks.

Hello sapoleon;

With Siemens S7 you can use any mix of languages you like in your function blocks. I generally use LAD for "standard" programming, but will use FDB for process blocks, and SCL for high math and trackingfunctions. STL is the fatsest to execute, and the most flexible, but the harder to debug (and sometimes understand). SFC is great for sequential processes, but has a very high overhead. Each language has its drawbacks and advantages, and every programmer I've worked with has his own preference. You'll have to try them all, and determine what works for you.
Hope this helps (and encourages you),
Daniel Chartier

sapoleon said:

I just get a 3 days curse of siemens PLC's

Click to expand...

So, I have to ask - is this a typographical error (with course being the intended word), or a Freudian slip, or an editorial comment on the user friendliness of Siemens?

I vote CURSE. LOL

Well, it may have been my subconsious.... (if that is the word)

The truth is, my english is not perfect, and I course and curse, are a pair of words that I not allways remember which is which.

And to be honest, after lerning 2 other languages after english, it's like a bit of a salat in my head. Sometimes I don't know in which language I have said a word.

But no, I have cursed Siemens when I made a project that have to talk to 11 MC440 (microdrives) from an Omron PLC. I post some questions in this forum also... That was a pain! (and not only in the a..)

At first sight, the SCL seemed very friendly, I can't say the same for the Siemens Lad, that I found it very NOT user friendly.

I almost forgot....

Thanks Daniel. I think I will just have to hope for a pair of projects so I can get the hand on that. And make the basis for the use of S88 with the Siemens PLC.

I use Siemens S7 ladder logic almost exclusively.
Our electricians prefer it that way.
I would like to also use SFC, however management does not agree that we can get enough benifit to justify the cost.
I don't usually use STL, only when I cannot do the function I want with ladder.

Some of our projects are done by German companies, and for some reason the Germans like STL most of all, will use FBD if pressed, and turn their noses up at ladder.

I have written many S7 PLC programs in ladder only and have not found the need to use anything else.

I use ladder almost exclusively. It is more easily read by field service and maintenance personnel and I like it better myself..... However I will sometimes use SCL for math intensive blocks because it is just plain easy and quick compared to ladder for heavy math. I also use STL occasionally for advanced routines that Siemens doesn't provide simple ladder functions for. In either case it's usually a difficult well tested routine to perform a function (That probably should have been provided as a standard function) with simple parameters passed to and from it so other personnel can treat it like a regular command and not worry about what's inside.