PLC Textbook

You address the subject as "PLC Textbook". If you want a book specificially about PLCs it will be closer to the technician level than the Masters in EE level. It's not that engineers don't work with PLCs; many do. But the market for books on PLCs would have to include technicians. For someone at the graduate EE level you will want a more general book. There are several subject such a book might cover: control theory, control strategy design, or process (chemical processes, pharmaceutical stuff, pulp and paper, etc.)

If you name a subject, I and, I am sure, others here will have suggestions.

You might also go to

and click on the book store link at the top, or check Amazon or B&N. For many of the books at Amazon you can view the table of contents, index, and other samples. There are some good PLC books at these sites, just expect them to be written for a combination technician and engineer readership.

And check back here for suggestions on more specific subjects.

John Shaw

Hello John, Thank you very much for your response, and I apologize, you are right, now that I read my post not even I understand what I wanted to ask :-). Here is the situation: I have asked here a couple of times regarding PLCs because I have noticed that most of you is the topic you talk about, and I guess that that is because it is what is used in the Industry; I am about to finish a Masters/Electrical Engineer Degree and I have not seen at all any topic related to that, so I want to take a look at what they are and how they work. I have already convinced one professor to buy a couple of them from Automation Direct (with a power source and a couple of proximity sensors) and we will be testing them very soon. Now regardin the application, I would like to know if there is any book that talks about Ship's control (and I am not talking about equations of motion or the like): engine room applications, steering probably, power generation, etc. If you or any other out there knows of a book I would really apreciate it.

Thanks

Mariano

Mariano,

Just a comment, and not especially helpful :-) There are two aspects to any engineering subject: The technique and the application. The technique is for technicians. PLCs belong in that class. They are designed to be easy to use. If you can use a calculator, you can program a PLC. The application is where the engineering comes in. That is where the real knowledge is. Knowing HOW to program is easy. Knowing WHAT to program takes thought and understanding. Once you know your application, in your case ship control, you can apply whatever techniques are common practice at the time. My application is process control. The techniques I have applied include relay logic, pneumatic controls, pneumatic logic, PLCs, DCSs, and others. In the future other technologies will arise but the basic application remains the same.

Having said that, I can only add that you are now at the beginning of the 'lifetime of learning' phase. Books will be relatively few, specialized and hard to find. I don't know if there is one of the sort you are looking for in your field. There will be, however, a larger number of books on specific pieces of equipment such as turbines, boilers, generators and electrical protection. My web site has articles on controlling pumps, heat exchangers, fired heaters and vessels. Some of that might be relevant.

Walter.

Ah! I thought you find it with a web search. Actually it's

Walter.

No, there isn't. But never tell a person that found it difficult that you don't expect to find it difficult. It annoys them. It happened to me once that I was asked if I had PLC experience and I hadn't. I didn't get the job. A friend later said, "You couldn't have wanted it all that much then." The weird thing is that two years later I was in a position of redoing that person's work because it was inadequate. The problem was that he didn't understand the application.

Having said that, it always helps if you've done it before. Buy a cheap one on e-bay and play with it.

Walter.

Walter, Sorry, I never thought about it, your site is the first hit in google :-)

Thanks, I will sure look into several of them.

Mariano

That's almost always the critical bit.

I agree, but ladder logic is a bit reversed if you're used to conventional programming. It might be a case where having a limited amount of computer programming knowledge actually works against you during the first part of the learning curve. The micro-PLCs are more like assembler language (absolute references to memory locations ("coils"), inputs and output) and their "operating system" is just a big loop that looks at inputs, calculates the outputs and repeats. The evaluation of ladder rungs is a stack-based forth-like process at the machine level. For example, to evaluate an output that is two inputs A and B in "series" the machine pushes A onto the stack, pushes B, executes an "AND" (series) and pops the result to the output. Graphically it might look like:

----+------------------------------- | | --- A --- | --- B --- | | (OUT) | ----+-------------------------------

More sophisticated PLCs do a lot more, and can have procedural language(s) as well as ladder logic and special functions for PID, motion control quadrature inputs etc. etc.

Best regards, Spehro Pefhany