I need help

I need help on a college assignment about the design and operational characteristics of PLCs. My tutor gave me the assignment and I know nothing at all about them. Ive searched the net and all i find is manufacturers websites. This webside has given some insight to PLCs but not specific to the questions.

Heres the questions:

1) Describe the design characteristics of typical programmable logic devices - Give Examples of the unitary, modular and rack-mounted methods of implementation.


2) Describe different types of input and output device - In your descriptions give examples of mechanical switches, non-mechanical digital sources, transducers and relays.


3) Describe the types of communication link used in PLC systems - Give examples such as twisted pair cable, coaxial cable, fibre optics and networked links.


4) Describe the internal architecture of typical PLCs - Your examples are to include the CPU, ALU, storage devices, memory, optoisolators, input and output units, flags and shift registers.


5) Describe the operational characteristics of the CPU - Mention in your description scanning, performing logic operations, continuous updating and mass I/O copying.



Many thanx in advance

Do you have any part of those answers now? If you do share that and you will be guided to the whole answer.

Drewcrew6

I have only been given a few diagrams of rack mounted, modular PLCs etc. So the information we've been given is very small.

This is from the HNC course. Did your tutor give you a bibliography of reference material from which you might find the answers?

RANT
Many of us here view the HNC course with disdain. The reasons are twofold.

First, we get several queries each year just like this one, where the student simply copies the questions from the exams without showing any evidence of having researched the topic. This is akin to saying; "I'm too lazy to try to find the answers to these questions myself. I'll ask someone else to do my work for me".

Second, so many of the questions themselves are irrelevant. Just as you don't need to know anything about metallurgy to use a hammer properly, it is not necessary to memorize a bunch of obscure terminology to learn how to apply and program PLCs.
/RANT

The questions are really vocabulary questions and the answers are to be found in the text of the questions.

2) Describe different types of input and output device - In your descriptions give examples of mechanical switches, non-mechanical digital sources, transducers and relays.

Click to expand...

Mechanical limit switches, non-mechanical sensors, transducers and relays are examples of I/O devices.

what is HNC if i may ask?

Afroman

Can I recommend that you trot off to your college library and look for a book on the subject.

I can recommend a book by W. Bolton called - Programmable logic controllers.

Within this book you will find all the answers you require and more.

If you want to make PLC programming a career you would like to follow then perhaps if you wander down to your local W.H.Smith and buy the mentioned book.

A point to note - I do not in any way what so ever profit from the sales of this book.

Paul

Forgive me if things are different now, but wben I was in school, the answers to all my homework questions could be found in or derived from, the course material or my lecture notes. You might want to start there.

SLaubach

HNC stands for Higher National Certificate, a qualification that is one step below a degree, or at least that would be the next logical step for someone educated to HNC level.

Paul

Show some proof that you attempted to do this yourself and people will help you with the remaining problems that you have. Its as simple as that.

get some books

There are books that can give the answers to your question one of them is Fundamentals of Programmable Logic Controllers, Sensors, and Communications (2nd Edition) -- by Jon Stenerson;

Have fun,

Gery

PLucas said:

SLaubach

HNC stands for Higher National Certificate, a qualification that is one step below a degree, or at least that would be the next logical step for someone educated to HNC level.

Paul

Click to expand...

Interesting.
I had always assumed that HNC was a school. You are are saying that it is school independent? So the Unitary question could be coming from several schools? Or are we seeing people from just one school?

afroman said:

Heres the questions:

1) Describe the design characteristics of typical programmable logic devices - Give Examples of the unitary, modular and rack-mounted methods of implementation.


2) Describe different types of input and output device - In your descriptions give examples of mechanical switches, non-mechanical digital sources, transducers and relays.


3) Describe the types of communication link used in PLC systems - Give examples such as twisted pair cable, coaxial cable, fibre optics and networked links.


4) Describe the internal architecture of typical PLCs - Your examples are to include the CPU, ALU, storage devices, memory, optoisolators, input and output units, flags and shift registers.


5) Describe the operational characteristics of the CPU - Mention in your description scanning, performing logic operations, continuous updating and mass I/O copying.



Many thanx in advance

Click to expand...

I hope these hints and manufacturers (not answers) help steer you in the right direction. We use Allen Bradley PLCs at our lumber mill.

1. SLC 500 Fixed - Unitary, PLC 5/40E - Rack Mounted

2.Inputs - Limit Switches (Allen Bradley), Photoeyes (Banner), Prox Switches (Allen Bradley), Temposonics (MTS)

Outputs - Motor Starters (Allen Bradley), Solenoid Valves (Parker), Horns, Lights, etc.

3. Use online manuals for the following protocols to learn about different Communications methods. Allen Bradley Data Highway Plus, Ethernet (Coax), Remote I/O, etc.

4. Answers should be in the first few chapters of any book about PLCs.

5. Same as 4 or also check out online hardware manuals for any PLC for specs.

I hope this helps.

Vetteboy

Rick

HNC is a college qualification.

As an apprentice the various qaulifications you would undertake in order of standard are:-

City and Guilds parts 1, 2 and 3 certification in your chosen subject i.e - electrical engineering
ONC (ordinary national certificate)
HNC (higher national certificate)
Degree.

At least thats the way it was done when I trained some 20 years ago now. I think they have done away with the City and Guilds bit now and they do what's known as NVQ (national vocational qaulification)

So all these question received are from students at many different colleges studying for the same qualification.

Paul

There's alot of free downloads at www.industrialtext.com about PLC's.

--edited out-- by Phil

--edited out by Phil--
goodbye afroman.
Regards,
Phil
PS- I'll only keep this thread(minus the deleted post here) since it has some information of value scattered throughout. Phil