ghid

Education in PLC programming

9 posts in this topic

Hi, I am concerned from a while, about my way of organizing and structuring my ladder PLC programming. I don't follow any rule or structure. I have problems in tranforming the " to do" machine requirements in ladder code. I don't see my code to be neat and I am afraid of my code stability. I do programming in steps. I have knowledge about scanning cycle and plc's. I have also some knowledge in C programming but I have the fealing that my programming is chaotic. I want to say that I have made 10-20 machines to work by my self, I'm not at my first steps. But I want to do something like software engineering with my way of programming. Do you know programming book that can help me? I want to be more profesional and self confident. Please help me to go on the next level. Thank you.

Share this post


Link to post
Share on other sites
You must advise which PLC You are trying to program. IE Siemens Allen Bradley Mitsubishi Rodney

Share this post


Link to post
Share on other sites
I am talking generaly, beacause I am programming different tipes of plc: siemens, omron, schneider. I am talking about programming techniques that can be applied in ladder. I am asking for methods of arranging and structure ladder programs or methods from other languages, for example C that can be transposed in ladder. Books or other sources. Thank you.

Share this post


Link to post
Share on other sites
Structured text programming is similar to C. But as for as a 'best practices' or 'recommended techniques' goes, every vendor will recommend their own things. The end result is do what works and you can understand. Many programs I have seen and done I have based the sections of code around the various parts of the machine. I saw other programs who always write all of their outputs at the bottom of the program, and turn on internal bits higher up in the code. There's no silver bullet to answer all your questions...

Share this post


Link to post
Share on other sites
I just popped onto this thread because I was thinking of writing a similar one, but I may be a little more up the ladder than ghid. What I was looking for was a guide, or class even, that someone might recommend to help me understand the depths of RSLogix5000? I have designed and programmed a robotic pick and place machine, where I use everything from a Ethernet I/P network to communicate to the drives, AOI's for those drives, and multiple programs of ladder to control it. I feel comfortable and think I did a pretty good job, especially coming from a Mechanical Engineering background, but I want to learn more and get deeper. Does anyone have any suggestions?

Share this post


Link to post
Share on other sites
everybody starts with chaotic programming... to tame the code, one must make it modular and structured. this means breaking problems into smaller, easier manageable parts, then debug each of them independently from rest of the program. For example, there are program examples in download section such as pick and place etc. Goal is to get PLC to control machine and accomplish various things. All of this can be broken down into sequence of steps. At the same time PLC should be aware of various conditions and display status and if needed, abort program execution. All actuators should also be easy to control manually as well as when under control by program. Any task can be broken down into smaller steps, usually spreadsheet is great way to organize things and keep track of everything (comments, addresses, structures, pictures...) and share if someone else needs to take over project. Another thing is that we do not want to make million unique code snippets. Goal is to make just few snippets and repeat them many times. Example, code for alarms is pretty much cookie cutter. Generally it is something to give to student to type in. Similarly there is bunch of other "nuts and bolts": - sequencers - toggles - bit shifts - motor controls - security - robot control (PNS or AutoExternal or whatever) etc. once you have your handful of standard blocks, rest is like playing with Lego... just put them together. if you have the blocks created with some basic care, they will translate easily into any PLC.

Share this post


Link to post
Share on other sites
Ok panic mode, so I think I've started to understand most of those things you mentioned. I utilized small programs to control portions of the machine individually, and then had them talk to each other when necessary. The above is the additional nuts and bolts that I want to understand. Because I haven't run across some of this stuff before being an ME, some of the concepts are not straight forward for me to understand when reading them straight from the manual. I was wondering if there was any "reads" out there that put some more examples to tools like you mentioned, that would make it a little easier to learn. I'm really getting into the Controls side of Machine Design, and gaining a deeper knowledge and understanding of the tools available is on the top of my To-do List. Thanks!

Share this post


Link to post
Share on other sites
Ron Beaufort here on the forums offers training on RSLogix5000 and I've heard good reviews from his students. Not sure if this is the right level for you. http://ronbeaufort.com/

Share this post


Link to post
Share on other sites
I have come across that training, and keep going back and forth as to whether it would be a fit or not. Coming from an ME background, I'm sure there are many gaps that could be filled in a training like that. On the other hand, I've been programming for a little while as well, so I want to make sure there would be enough information for me. It might be worth just getting in touch with them and having this discussion.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now