PLC Programming

Hello, I have recently obtained an Associates in programming, and did not cover any PLC programming. I plan to go for my Bachelors in the fall, but I would like to learn this language I have downloaded the Learning Pit Simulator and have no idea how to use it. I have read some through the forums, but still a little confused. Does anybody have any suggestions on where to start, Ive noticed the different types of PLC's; which is better to learn? Thanks

There is no one PLC Programming language. Most PLC programming falls under one of 5 groups:

• Instruction List (IL)
• Structured Text (ST)
• Ladder Diagrams (LD)
• Function Block Diagram (FBD)
• Sequential Function Chart (SFC)

Click to expand...

http://home.dei.polimi.it/baresi/papers/anipla2.pdf seems to be (i just skimmed the first few pages) a fairly technical peice on the differences. There are some IEC standards on PLC programming in each of the above types but each hardware vendor may have their own caveats on each of these programming types.

And of course there are also other vendors that offer I/O controllers that are similar to PLC's but can be programmed in a variety of languages. MOXA and Rabbit are two that come to mind. MOXA has a product that is basically a linux computer with built in discrete I/O, and Rabbit has it's own C compiler and libraries for it's controllers.

Edited to add: Ladder is probably the most common here in the US. At least in the industry I work in. And http://www.plcs.net has an excellent introduction to Ladder programming.

Thanks monkeyhead, very helpful.

Sir,

As was mentioned previously, there is a different software package for each PLC manufacturer. Each package may conform to the standards set forth by IEC, but that is where the similarities end.

Each manufactuer presents a different manner in programming, even though they may comply with IEC. Even though the theory may be similiar, the method in how you create that rung will be different.

For instance we use two rungs for a timer or counter because in our set up, our registers are configurable, rather than being preconfigured.

We have a number of individuals that download our software to learn with.

It is ladder logic based and includes a simulator, examples, and programming manual. It is free for download and only requires registration for receiving the password.

Hope this helps.

God Bless,

At the top of the page is a link labeled Learn PLCs. Thats hands down the best place to start on the net. Its basic and easy to understand. After you have grasped the fundamentals, download Hugh Jack's book for a more advanced treatment of PLC programming.

Or this thread for similar topic.

http://www.plctalk.net/qanda/showthread.php?t=39827