Unitary, modular and rack mounted PLC

Hello, ive got an assignment to do for college and two of the questions are:

Describe types of unitary, modular and rack mounted PLC'S with respect to their application and versatility..

and.. Explain and justify the factors that must be considered when choosing the size and type of PLC required for a given application i.e cost, vercatility and ease of use

I cant find anything on the internet at all, any answers would be appreciated.

and away we go

let the games begin!

let's be gentle ...

Greetings NitrogenY3K,

welcome to the forum ... before you get "flame broiled" let me suggest that you try using the "Search" button at the top of the forum page ... your question is one of the all-time "most asked" on this forum ...

incidentally, you can probably just delete this entire thread by going to the "edit" mode ... we hope you'll hang around ... but this is NOT a good way to get started ...

PS Edit: "HNC" is a good search item to start with ...

NitrogenY3K said:

I cant find anything on the internet at all,

Click to expand...

Did you even look?

Re: Re: Unitary, modular and rack mounted PLC

Rick Densing said:

Did you even look?

Click to expand...

do any of the links answer the question? no they dont.

I have searched on this site and all that comes up are posters who continually moan at the original poster but yet fail to answer the question directky with any decent information

Actually, on one of the more recent episodes of this ongoing saga Ron Doran kindly posted a link to a text that addresses it exactly. Do some searching on this site and you'll find it. I didn't bookmark it, because this is a question that, in twenty years of automation, I have never needed the answer to!

http://www.freestudy.co.uk

Edexcel subjects: Prog. Logic Controllers

Re: Re: Re: Unitary, modular and rack mounted PLC

NitrogenY3K said:

do any of the links answer the question? no they dont.

I have searched on this site and all that comes up are posters who continually moan at the original poster but yet fail to answer the question directky with any decent information

Click to expand...

If you followed the link that I clicked, you would be taked to rsdoran's links which explain the answer.

You might get some more help if you posted what you thought the answers were. You would then get some feedback.

Re: Re: Re: Re: Unitary, modular and rack mounted PLC

Rick Densing said:

If you followed the link that I clicked, you would be taked to rsdoran's links which explain the answer.

You might get some more help if you posted what you thought the answers were. You would then get some feedback.

Click to expand...

I dont have the slightest clue what the answer is.
I had a look at that pdf file and there wasnt much info on the types of plc, only a coupke of lines.

how much more spoonfed can you get? yes theres only a couple of lines but they tell you exactly what you need to know.

I dont have the slightest clue what the answer is.
I had a look at that pdf file and there wasnt much info on the types of plc, only a coupke of lines.

Click to expand...

UNITARY
The Unitary PLC contains every feature of a basic system in one box. They are attached to the machine
being controlled.
Example: Allen-Bradley Micrologix 1000

MODULAR
These use a range of modules that slot together to build up a system. The basic modules are the power
supply, the main module containing the CPU, the input module and the output module. Other modules such
as A/D converters may be added. The main advantage is that the number of input and output terminals can
be expanded to cope with changes to the hardware system.
Example: Allen-Bradley Micrologix 1200

RACK MOUNTING
This is a similar concept to the modular design but the modules are on standard cards that slot into a
standard rack inside a cabinet.
Example: Allen-Bradley SLC 500

NitrogenY3K said:

I dont have the slightest clue what the answer is.
I had a look at that pdf file and there wasnt much info on the types of plc, only a coupke of lines.

Click to expand...

The PDF linked to is what Edexcel use, in case you don't know EdExcel are the HNC examining board.

The PDF has given you the basic description required, you then have to 'expand' on this basic information to answer the question.

So, have a go at 'expanding' on this basic information...

In the old days (when I took my HNC) we had to use libraries, books etc and our good ol' grey matter.. The internet wasn't around then, so there was no forum for me to log onto and ask the worlds finest automation engineers for help. Go back to basics and research this a bit more, use books! I will even recommend one for you.. Programmable Logic Controllers by W Bolton. See if your college library has a copy. You might find it useful for the PLC module.

Paul

Which pdf file did you look at? The file outcome1.pdf has about as much information as you're likely to find on that particular topic. Of course, it appears that the author of the document didn't have much of idea about the difference between modular and rack mounted.

Yours is a question asked by nobody except the HNC proctors.

NitrogenY3K said:

I cant find anything on the internet at all, any answers would be appreciated.

Click to expand...

Why would you check the internet first?

Is there a text book for this class? It should have an index.

"Searching" the internet (most of the time) is only slightly more productive than wandering around the library looking for a book on subject X, wouldn't you think?

well searchin the internet is not difficult at all.. but u need to be aware of what u need to be searching for..

for me, i m lookin for same sorta things,but everything i search for, i don't understand the results...

any ways, relatin to the topic, what would u search for if u were lookin for manufacturer's data sheets of the unitary, rack, or modular plcs...

n manufacturers do not, as far as i know, differentiate them by types as such..

NitrogenY3K, personally I give most studenst the benefit of the doubt and offer information that if they take the time to read will offer an abundance of information on the subject.

I believe the freestudy site offers an abundance of information especially for those taking the HNC courses. It may have its flaws but I believe it follows the HNC curriculum and offers the answers required to pass the HNC.

NitrogenY3K, get off your sorry backside and read...books or net doesnt matter...take the time to read. Noone is going to hold your hand nor provide more than I already have. Your attitude is just asking for more derision which IMHO you are highly deserving of. I regret wasting my time on you.

kakarat
The word unitary (or brick) is not common with manufacturers, they prefer terms like micro-controller.

The term modular is used for many systems...Ex: AB describes the SLC 500 as modular: http://www.ab.com/plclogic/slc/index.html

The PLC5 AB likes to use the term modular architecture to describe it. It uses backplane and rack mounting so could be used as an example for "rack" http://www.ab.com/plclogic/plc5/systemdesign.html#functional

If I were to take the time to define those terms it would be something like this:
unitary A single unit with fixed number of I/O.
modular A plc with power supply capable of having the number of I/O, communications expandable but limited.
rack A plc that uses a rack holding a separate power supply, cpu, I/O, capable of large expansion.

NOTE: This is a simplistic overview because the dividing lines between the types are decreasing...ie now micro-controllers ( once unitary) are capable of being expanded. Networking capabilities have increased so much that its now possible to use micro-controllers in places that once had to use large rack sytle systems because of the number of I/O involved.