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Searching study mates for PLC study !

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Hello ! I have been teaching PLC for approx 6 years on basic and intermediate level. I got this idea that I will try to make a book, a e-book or a compendium or something on the PLC subject. At least I will try to develop the technical skills required for such a book, even if the book will be written or not. I think there is a rather nice source to look into in Hugh Jack's free PLC book. http://claymore.engineer.gvsu.edu/~jackh/books/plcs/ This book is based on the Allen Bradley, a PLC that I have not tried for one second, I don't know it at all. Have been using Siemens S-7 300 and 400 series and some Telemecaniqe and Omron. I think it could be an interesting idea to start up with the book of Hugh jack and to see if it's possible to modify the examples in this book so it will fit with Siemens and other PLC's I have done some of this "source code translation" already, and tested it, so I know for sure that it can be done. I do not see it as a target to develop some "Simens only" texts or something like that, but rather something more general for all PLC's with possibly Step-7 as the basic for it all. (Because of it's flexability.) (First one programming task can be explained for Step-7 then for Omron, Telemecaniqe, etc.) From lets say a "Modified and translated Allen Bradley point of view" it would then be given some "reorientation" with more "Siemens alike spesialities". (What about first making chapters explaining the general programming methods, and then aditional sub chapters that shows how these principples or metodes can be used for each "brand" or programming system.) The target for this project - first of all learning, playing and having fun. Second - to se what practical purposes it can be used for. I think such a project could be more learning, playning and fun if it's more people than one involved with such a project. (Projects before - Linux open source.) If anybody should be interested to take part in such a "game" please leave a msg, here on this board or send a mail to: arne22 at gmail.com Best reg Arne.

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I'd say you better contact Mr Hugh Jack and ask what he will allow. He also has a GNU released for his book. Make sure you read and fully understand his terms for letting you read his book for free.

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Yes of course. But to read or write a book could be two quite different things. Even though you start up with one book for some discussion and some studies (and some other books as well) it is not obvious that you will make a copy on this book at all. Siemens has released a rather large number of free e-books related to their equipment and programming tecniqes for these: http://support.automation.siemens.com/-snm...bjaction=csopen Of course one alternative, technically would be not to write a "book" book at all, but just rewrite the excamples from Hugh Jacs book for Simens, Omron, etc (for public or private use). The other ekstreme alternative is to rewrite it all from the bottom. If you compare the programming techniqus from the book of Hugh Jack with the Siemens released stuff, I think one thing thats struck you is that their content is quite much different. I think that at least the chapters I am looking at now of the Hugh Jacs book, 11 Flowchart based design and 12 Statebased design they give, I think a lot of interesting ideas about programming techniques that I will call "programming techniques for programming of machinery controls". If you look into the Siemens relased books, I will rather call that (with right or wrong) "programming techniques for programming prosess plants and distributed systems". It is now so easy to see what you will end up with, before you have started at all. I think that translating the Allen Bradley programming exsamples and programming methods to Siemens Step 7 (or other PLC's) can give som a little bit "stange looking" Step 7 programs, but it obviously can be done. Possibly the reason that it looks "strange" is the way that I do this "translation" and that a discussion around it all might lead to new and improved programe designs. (Close up to or quite different from the starting point.) Of course the copy rights of any "book" or "e-book" must be respected. So far I don't know if it's anybody "out there" that is interested in participating in such a project or doing some "discussions, research or studies". If there will be a project at all, Hugh Jack will be oriented.

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Excuse me, the link to the Siemens libriaries apeard not to be the right one. I hope this will work: http://support.automation.siemens.com/-snm...e=cs&jumpto=541

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Hi, The book is licensed under the GFDL that (like the Linux license) allows others to copy, modify, sell, or set fire to the document WITHOUT my permission. To help those that do want to edit it I posted files that may be helpful. (Unfortunately my tool of choice is Adobe Framemaker. I have also exported RTF files, but you will not be able to edit the images.) The GFDL does have a couple of requirements in terms of giving credit, but they are not that complicated. Originally I wrote the book to support an engineering coure I teach. I chose to use Allen Bradley equipment because it is very popular in our area and there were significant (although out of date) collections of donated equipment. Also, by focusing on one PLC platform I was able to explore the controllers in greater depth, and avoid the generalities that many books fall into while trying to cover all controllers. I have toyed with the idea of expanding the book to cover other PLC types, but time, need, and equipment have held me back. From your earlier comments it sounds as if you have the necessary elements to move forward with a Siemens version. I know many people would appreciate such a version. Hugh

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Dear Readers, Even though the above post is "unregistered". I can indeed tell you for a fact it was the "real" Hugh Jack that posted the above comment, because I summoned Mr. Jack to comment on this post.

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Hello Hugh Jack and chakorules ! I think the existing book is really great. I also think it is a bit "general". If not I could not have used it because I have never programmed a Allen Bradley PLC. I think it will work ok to translate the programs themself to "Simens syntax". I do not have a PLC at all for this "translation", only a Laptop with Siemens Step-7 with S-7 simulator. It is actually my experience that courses with only one PLC in the class and then PLC simulators on each PC works quite OK. Actually there is also a free PLC simulator that works a bit ok, that anybody can download, the Zelio: http://www.schneider.co.uk/software/zelio_soft.htm I believe all of the programming examples can be modified to work with Siemens Step 7, stil with the existing programming prinsiples intackt. I'm actually wondering if it could be possible to "port it" or some of the programs also to the free Zelio environment, but I think this will not be so easy (or possibly imposibble, don't know for sure.) (I think it does not have the MCR function.) My idea was intentionally just that it might be a idea to write down the modified programs ant that it might lead to bether quality if some persons around were working on the project. Best reg Arne. (Stavanger, Norway)

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If the Siemens does not have an MCR function it may have something similar. If it does not you could implement the ladder logic in other ways such as, A. Put the state logic in subroutines, as other programs. Only call the subroutines when that state is active. B. On the first MCR line use a GOTO/jump statement. Change the NO contacts to NC. When the state is not active the state program will not be executed.

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Hello ! Thanks a lot for your comment. The Siemens step 7 has a MCR function (even though I am not used to use it.) Have now translated some of the programs to Step 7 and basically all of them works. On the other hand using the MCR function of Step 7 seems to involve some strange behaviour and the programs tends to be a bit "messy". I think it is possible to rewrite the programs completely (regarding the practical syntaks) to give a bether adaption to Step 7. On the other hand the basic programming principles and the way problems or situations are analyzed and solved can remain unchanged. I think the idea of building logics consisting of more than one program block is rather interesting. Have not tried this implementation yet, but I think it can be done. I think the very strong side of your book is how things is described in a kind of "top down approach", first the general rules behind it all and then the practical solution adapted to each situation.

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I am glad you are finding the methods useful. One of my prime motivations for writing the book for my students was to provide higher level design methods so that program design could become more routine and reliable. After all, Many of our graduates end up designing control systems soon after they graduate.

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Be careful using the Siemens simulator, it will allow you to do things that a real processor may not allow, also sometimes it does not respond in the same way as a real PLC.

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If there is interest, I can also work on converting some of the examples to either Mitsubishi, Modicon or Omron. Been a while since I worked on Omron, but it will come back. I haven't read the book cover to cover, but have browsed it before and must thank Hugh Jack for the amount of effort he obviously put into it. I had never programmed AB (Omron , Mitsu, Siemens (S7-200), Modicon I have) and it did give me some insight into the AB lingo. I also teach training classes, but not to that scale. My typical PLC class is 2 days hands-on, with vendor-approved (and me modified) training materials. We certainly don't get into level of MCrs in the first 2 days, but I do offer an advanced 2 day class, which I have only had to run once. Seems most of my customers get enough out of the basics and can run with it from there...

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Snerkel -> We have been using the Siemens Simulator for ca 3 years in classes of a typical size of 10-15 persons. We have had 2 ea S-7 - 300 and one S-7 -400 for testing. The programming training has mainly been performed by use of the Simulator, so each individual person have had one PC with simulator available. During these 3 years it has not hapen one single time, as far as I know, that program syntaks or program methods used at the simulator has not worked on the real PLC. There are differences - You don't have to define the hardware at the simulator, and you can use adresses, inputs and outputs that does not exist in the real life. For training purposes, (and for prototyping) I think this is no problem at all as long as you know that you have to "declare" or "define" the hardware correctly before you load the program down to "the real PLC". If you are avare of examples of differences exept for this, I'm very courious to know. (I have some strange "problems" regarding syntax for the mcr function and I have not tryed it on the real PLC yet, only on the simulator.)

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I'm not sure if it's what Snerkel's refering to or not, but there is a problem with PLCSIM if you use its record/playback facility. The problem arises because PLCSIM stores each step of the program Bytewise, not Bitwise. This means that if you want to pre-record one part of your program to play it back while manually simulating another part, to check for correct / incorrect interaction, the part of the program must not write to any I/O which is in an I/O-Byte which is part of the pre-recorded program. If it does, when you manually write a value to the I/O it will get overwritten by the pre-recorded value on the next step of the playback. It's a pity they had to spoil a potentially very useful feature by being too cheapscate to do the job properly.

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RMA -> Thanks for your information. I were not aware of this limitation of the Simulator, but on the other side I think this is a limitation that will not affect the "translation" or the testing of any of the programming exaples in the actuall book (??!!) (For some more Simens specific programming, using OB's, FC''s FB's, DB's etc, the situation might be another ??!!) The very clear and obvoius difference between the simulator and the real PLC, is as I see it that you do not have do define hardware and you can use non existing Inn / Outs on the Simulator. When you know about these restictions or "specialities" it should not be to dificult to "compensate" for it. Of course any program developed on a Simulator, as a general principple, should be tested on "the real thing" in the end to verify functionality. Best reg Arne.

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Hugh Jack -> I must also say thanks for the book ! I have tried to buy in some commersial PCL titles, but the general limitations of those books, I have bought and according to my opinion, is that they are rather oriented against syntaks and examples, but in general, it is difficult to find books that explain the teories and methods behind it all very well. I think the book of Hugh Jack is different in this way, it explains the teory and the general principles behind it all wery well, and then the programming examples "on top" or "after" that. I think this theory and basic programming techniques can be adapted and used for any modern PLC. I have not read the book really in tho the dept, but I have looked trough it all and also tried some of the examples (by using simulator, and after translation to Siemens Step 7). I think Cris sugestion of making "translations" of the programming exaples to different PLC's, actually the most common used PLC's, is a very good one ! I could try to make a Simens step 7 version, and I would eventually be happy to first issue it as a beta code and then hopefully receive som ecomments how to make things bether. (There is allways a lot of ways .. ) When it comes to Omron, I think this is one of the PLC's that alredy from a starting point is rather close up to the programs of the book. (Replace the L(atch) with a S(et) and the U(nlatch) with a R(eset) and you are close up to be running. (Refering to the "old" Syswin software, have not tried the new Omron software.) Posibly the best idea would be not to try to write any new text at all, but just to make "close up to the orginal code translations" of the existing program examples to the different brands and programming systems (Telemechanique, Mitsubushi, Simens, Omron etc.) I think such an "amendment" (if successfully maid) could be usefull for those who don't have a Allen Bradley PLC, but possibly "something else".

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Just made a "close as possible to the orginal translaton" to Step-7 of the first example in chapter 11, to start up with something. Issued at my home Linux server. It might not be the best Step 7 program, but just a start. All program code in OB1. http://arne.dyndns.dk/plcbook/Chapter-11/Program-1/

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The first program in chapter 11 as PDF (Tried to experiment with jmp function and fc, fb etc but kept the MCR function after some tests.) http://arne.dyndns.dk/plcbook/Chapter-11/Program-1-a/

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I think my first program example works, but it might not be to good. Will try to come up with a bether design. I hope that we can develop program soulutions for some of the major brands, so that the free book can be used by "all of us" not only those who have a Allen Bradley. I think that those prinsiples and methods that is in the book actually can be adapted to allmost any new PLS.

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I think this programming of the first flowchart in Ch 11 is an easy one. I belive it can be implemented for most PLC's: http://arne.dyndns.dk/plcbook/Chapter-11/P...m-1-simplified/

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http://arne.dyndns.dk/plcbook/Chapter-11/P...rogram-11.16-1/

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The state based programs in chapter 12 seems to be easy to implement to the Step 7. (Or any other modern PLC I believe.) I hope that there is some people with the rifgt equipment that makes translation to the other brands and program systems as well. http://arne.dyndns.dk/plcbook/

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Arne, How did the later methods using Boolean algebra (delayed update and state transition equations) work on the Siemens controllers? Hugh

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Hello ! I think I havn't done that yet. "delayed update and state transition equations" Sounds interesting. Do you have a reference to a certain page ? (I will try to test it out if I know exactely wich page or program.) Best reg Arne

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