S7 Stl Challenge

Hi,

I wan't to know some other idea's for write something out in STL. I always program in lad and I even write simple programs also in lad. I want to make a change in that. STL is sometimes better because u can write comment next to each instruction, that's the reason.

The concept:

A mixer (AC Motor 4 kW) must have the folowing controlpossibillities:

- one start/stop button with a signalisation for continue use of the motor

- one start/stop button with a signalisation for automatic use: 5 secs mixing and 10 minuts stopped, again 5 secs mixing, and so on...

- 1 emergency stop.



I would do it with a POS Flank detection and Set/Reset instructions. For the 5 secs mixing - and 10 minuts stop _ I would use timers. I would make a parameterisable block. But, that's my thinking in lad. I know it can be shorter in stl, let me learn from u guys,

thanks,

best Regards

CoMbo

I won't do the program for you but I will give you some hints.

Why don't you write your program in LAD program then view/edit it in STL. You will find that anywhere from 20-40% of the instructions are not needed. First optimize out these LAD specific STL instrucitons. These are the instructions are the ones that use the BR status bit. Next notice that LAD is very inefficient because all the parameters must be loaded at the beginning of a block and the result must be stored afterwards. You will see what I mean if you try to add three numbers together. To add A,B & C and store the result in D requires that A and B be added and the result is stored in a temporary variable. Next the temporary variable must be added to C to yield D.
An STL programmer can simply:


Your LAD techniques will work in STL. When using STL you will develope more techniques that make your program even more efficient.
Other things to look into are the JL instruction functions and function blocks. It would also be good to have access to a very good STL programmer mentor to learn techiniques that you will not learn in a class room environment.

Hi

That's indeed shorther. I think I'm going to try out more STL programming instead of Lad.

Best regards,

Gerry

Combo,

there's one huge problem with programs written in STL: a lot of the maintenance guys out there are not as keen as you when it comes to reading STL.

LAD is much more intuitive to understand. I always urge my trainees to program as much as possible in LAD. This way they ensure the continuity of the production without being called out of bed all the time for no good reason at all.

Remember: not all maintenance people are programmers. In fact most of them aren't! Nevertheless they must be able to read the program to be able to solve the problems!

You could of course convince the boss to give everybody the necessary training (heaps of work for me, keeps my job safe ) but that will be very expensive.

Kind regards,

Okay

Hi,

Maybe you're right for some maintenance departments, but not ours and lot more like ours. There are 2 Siemens programmers (me and ...), and the electriciens don't know how to work with plc's; they yearly get some courses at VDAB or PROMATIC or SYNTHRA or SIEMENS huizingen; but, they never learn much. I'm sure that not one electricien can even make a hardware configuration, how bad is that ??

I think, that VDAB is not really good for courses.

Promatic is good

Siemens is good for us, but not for our electriciens, courses are sometimes in english at Siemens.

Synthra is good


Best Regards,

Combo

STL

I think that Peter Nachtwey is right. STL can be usefull for calculations of value's. Lad for all the other logic instructions.

Combo,

you're breaking my heart !

I think, that VDAB is not really good for courses.

Click to expand...

I don't think you have good knowledge about VDAB. I'm a PLC and SCADA trainer with VDAB. In fact, I'm one of the guys who have written some of the PLC and SCADA courses, along with teaching them (check out my website). If VDAB is not really good for courses, why are all my customers coming back for more? Maybe it's because they follow our recommendations.

Most firms only complain about the price of courses. If I tell them it's an investment for the future and you don't save money by lowering your investments, they're lost.

The ones who believe us, do agree after a while because they see it's true.

Giving people training and locking the programming devices away (as I have heard numerous times) is also not a very good practice to keep your employees up-to-date.

So: how much is VDAB really to blame. As I said before: why keep my customers coming back for more? Why are people even coming to VDAB after they have had a training at Siemens Huizingen, Promatic or Syntra (these are real cases, I can give you the names of the firms and their employees)? Because they have money to throw away? Because they like wasting time? Please tell me. I'm always looking to improve!

Maybe you can send me more details about the courses that were not that good, the people from your firm who followed them, the center where they went and who was their trainer (there are 7 VDAB centers in Flanders where you can get PLC courses with a total of 9 trainers for PLC). I would be happy to investigate what went wrong, so we can improve. After all, every unhappy customer is at least two customers lost.

Use STL only if there is not other way with FUP or KOP (LAD).
STL is as assembler and that's why someones have developed COBOL as Ladder diagram is, clear and understandable and bit-acrobatics is not necessary.

I have used STL very very much with S5, but I don't like that even it is "a little-bit" efficient. Following in online with long STL netzwerk (rung) is slowly, when Step-program updates focus row by row.

Please, believe what Jean told before.

Kay

Somebody told me, long time ago, that, the closer you write to machinecode, the smaller your program will be, and how more memory you will save. It's a microcontroller-programmer btw

About: Vdab

Vdab is good for people who work in a maintenance departement. They can learn from nothing to a basic knowledge. But, why study on your own, you get a bunch of papers and you can ask questions when needed, but it's self-studying, well, everyone can do the same at home. But, when electriciens follow some vdab courses, they learn, that's true, but after a while they have forgotten a lot,
Why ?? because they are not using there learned information. That's why they keep choosing for vdab, because they can restart at zero.

Synthra is not bad btw

Siemens huizingen is not really good indeed

But: Promatic is very good for programmers, not for beginners. It's expensive, but really good.


Best Regards,

CoMBo

Thanks for the support Seppo.

I know what I'm talking about, as most people who got answers from me have experienced.

I was a machinebuilder/programmer for about 10 years with Philips Electronics (filmcapacitor plant in Roeselare, Belgium). During that time I was constantly in touch with the maintenance people.
The next three years I was the chief of the Quality Control Lab in the same Philips factory.
Since 10 years now I'm teaching mostly maintenance people (but also programmers) about PLC programming and SCADA systems. BTW, I (and some of my VDAB colleagues) have been hired on several occasions by the Siemens Institute in Huizingen to teach their courses.

I'm very keen when it comes to the quality of the training at VDAB. I know open learning has it's drawbacks, but if somebody knows a system to teach without drawbacks please do tell me!

We at VDAB have always believed in the strength of an open learning system. It's a system where you learn by doing. And you know what goes around:

• Tell me and I forget.
• Show me, I might remember.
• Involve me, I will learn.

It's my strong believe this is totally true.

This is one of the reasons I always try to convince programmers to use as much ladder as possible. The maintenance people are capable to understand it, they feel involved and they want to learn.

The (sometimes complete) lack of interest of the maintenance people is in many cases induced by a too large gap between the knowledge levels of programmers and maintenance people.

Open learning is certainly not a question of dropping a pile of paper next to the trainee and subsequently waiting for the questions to arise. If the trainer is not involved, it can't work! So Combo, if that's your experience with VDAB please give us more info, so we can dig in to prevent this kind of experiences in the future.

BTW, you said

But, when electriciens follow some vdab courses, they learn, that's true, but after a while they have forgotten a lot,

Click to expand...

How can VDAB be blamed for this?

You first said

I think, that VDAB is not really good for courses.

Click to expand...

and now you're saying

About: Vdab
Vdab is good for people who work in a maintenance departement. They can learn from nothing to a basic knowledge.

Click to expand...

Obviously, you're not up-to-date about VDAB. Please do check out our company website or if you want more detailed info go to mine and you will see we don't stop at the basic level.

I would be very happy to welcome you in our center in Brugge to discuss this further.

Nevertheless, kind regards from

hi jean ,

just visited your site and i have find out that its not in english, i cant
understand the language ,is ther any translation or somthing , because im really intrested to learn from this web site, thank you

best regards.
khalil khalil .

okay

Dat is misschien nog een idee,

Deze 2 cursussen ken ik.

Simatic Step 7 - Basisopleiding
Simatic Step 7 - Gestructureerd programmeren

De basisopleiding heb ik een lange tijd geleden (enkele jaren) gevolgd in wondelgem. De cursus gestructureerd programmeren heb ik op zelfstudiebasis uitgewerkt in het bedrijf zelf waar ik nu werk. Naast deze heb ik masterdrives, touch panels, profibus-dp, en nog enkele bij promatic gevolgd. Misschien ben ik wat ruw in mijn uitspraken, heb een te lage dunk van het vdab centra. VDAB is eigenlijk niet heel slecht, maar ik weet dat je op zelfstudie basis met de cursus van het vdab evenveel kan leren en misschien nog meer wegens meer tijdsbeschikking, en dat vind ik er niet goed aan. Voor mensen met niks van ervaring met PLC's, die amper iets kunnen ga ik akkoord dat ze een goede assistentie krijgen. Bij promatic geeft men theorie in combinatie met praktijk, niet slecht denk ik. Van Siemens ben ik niet zo content. Wat waar is dat is dat mensen die het materiaal niet ter beschikking hebben voor zelfstudie, een vdab cursus aangewezen is.

Waar ik momenteel interesse zou voor hebben is Wincc. Bij synthra kost de cursus 12000 befs geloof ik. Bij siemens 50000 befs denk ik. Hoeveel is dat bij jullie ? En ja, daar hebben wij het materiaal nog niet voor, maar ik zou een project mogen uitvoeren binnenkort met een eerste Wincc scada pakket. Bedoeling is, wanneer we tapijt printen, moet men de screens steeds juist zetten bij ieder tapijt (soort bedrukking); De bedoeling zou zijn om het met POSMO A positioneerdrives te doen en een scada pakket (wincc). Iedere rapporten instelling van de screens moet kunnen bewaard worden, bij het drukken van eenzelfde tapijt van enkele maanden geleden bijvoorbeeld, moet men met een muisklik alle screens juit kunnen zetten. Natuurlijk gaat er nog een fijncorrectie (jog) moeten op zitten. Posmo a is geen probleem, maar wincc, daar heb ik nog nooit mee gewerkt. Wel ooit een beetje met Fix, voor de rest gebruiken wij enkel td17 en op17's.


Sorry for what I said about VDAB, I was a bit rude about the courses, anyway, I still think that 100% open learning is good, but u can do the same at work or home if you have the equipement.


groeten,

Gerry

Somebody told me, long time ago, that, the closer you write to machinecode, the smaller your program will be, and how more memory you will save. It's a microcontroller-programmer btw

Click to expand...

Memory is cheap to day.
Efficient not debends of program size, it debends of program quality as follow:

a)

FOR I = 1 to 100

  A(I) = B(I+1)

NEXT I

b) Next code is much much more efficient than code a)

A(1)=B(2)

A(2)=B(3)

A(3)=B(4)

A(4)=B(5) 

etc..100 times