plcs

I am new to plcs, and have been set the following questions, could anybody help me answer it, or let me know a web site which might be able to help. I cant find anything so far.

what are the various types of plc and what are there application in terms of:
a Standaloneand modular etc
b programming techniques
c cost - with and without analogue input
d Different manufacturers
What are the advantages and disadvantage of different plcs.

from the above plcs, give an explanation of a typical hardware, software, input/output, typical field devices and communication links.

describe the type of communication links and networks used in modern plc systems.

It sounds like you're taking the HNC course in PLCs. You're not the first to post questions of this sort. Do a search of this site's archives using 'HNC' as the keyword, and you'll find plenty of help.

Thanks Steve,
Only doing the new ONC, but the course content is almost identical according to our lecturer.
Rob Burke

Click on "Learn PLC's" above.

Towards the bottom of the page is a link to Manufacturers that has links to the various manufacturers, many who have prices and detailed info.

check the other info for learning about plc functions, etc.

And look into the Learning PLC's video and book too.

regards.....kck

The "almost" part must be calling it "Stand-alone" instead of "unitary&quot

I do feel sorry for you, Rob, in having to do this somewhat rediculous assignment, because you don't have enough experience to understand just how rediculous it is.

The search that Steve mentioned may (or may not - there are a few somewhat misleading answers in the archives) get you an understanding of the answer to (a).

THIS LINK could get you an answer to (d) - or it may not. That is a list of ALL manufacturers; what you proably want/need is a list of the most popular. And you, as a student have no way of knowing if "ControlLogix" is a manufacturer, a PLC brand, or programming software. So just looking through the site may or may not be enough.

Cost is something that will be very hard to look up, as most manufactuers do not post their prices on the web. You'll need to contact your local distributors to get those numbers, and since there's no sale in it for them, they may be less than willing to help you out.

This will be even more difficult because you don't know how "powerful" a PLC you need. It'a like asking you to price a "car (with and without automatic transmission)". Is it fair to compare a Yugo with a Ferrarri?

The "stand-alone" (usually referred to as "fixed I/O") type are pretty simplistic processors. If you need more 'horsepower', you then get a "rack-mounted" type, with no dedicated I/O, and you add as much as you need (discrete as well as analog). So how many I/O points are you pricing? The same as you have in the "fixed I/O" type, to keep you comparison the same? (or close, anyway. One "fixed" I know of comes with 12 Inputs - a typical Input module for a rack comes with 16 inputs).

Questions (b) and (e) would require that you actually use the programming software to understand what is meant here. There's much debate about whether this or that feature offered by a manufacuter is an "advantage", a "disadvantage", or merely a "sales pitch".

You won't find any listing on any manufactuer's web site, which will list the features that they support in any kind of way that you can compare them with any other manufacturer.

Could I do your assignment for you? I could, but you would have learned nothing, so I won't. I suggest that you go back to your instructor and ask for a better defined assignment. One that has some chance of being completed, without having to first become a professional PLC programmer.

Thanks for your reply allen, you have basically given the answer i was expecting with regards to costing.
From reading the achives for this site, the chances of doing the assignment are close to impossible.
For instance, I havve read about 20 times now that the terms unitary, modular and rack mounted are outdated and not used in the industry.
so the chances of finding this info on the net are virtually zero.
Could somebody help me by letting me no the standard terms used in the real world.
This might help when looking for the info I require.
thanks in advance.
Rob

Re: The "almost" part must be calling it "Stand-alone" instead of "unitary&

Allen Nelson said:

It'a like asking you to price a "car (with and without automatic transmission)". Is it fair to compare a Yugo with a Ferrarri?

Click to expand...

I think that Yugo never had and probably never will have the automatic
transmission. Ferrarris come with both auto and manual but I think
it is not reasonable to put automatic transmission in either one of those two.

for the same reasons

Now that you've mention the F word!!!

Ferraris are 'two a penny' or 'as common as muck'





You wouldn't see the British arm of the 'Yugos Owners Club' parading their cars at Le Mans!!

Paul

Paul,

Did you take those pictures?

glaverty said:

Paul,

Did you take those pictures?

Click to expand...

Yep sure did.

Paul

Re: Now that you've mention the F word!!!

PLucas said:

You wouldn't see the British arm of the 'Yugos Owners Club' parading their cars at Le Mans!!

Paul

Click to expand...

I didn't think there would be 'Yugos Owners Clubs' so just
for the heck of it, I checked if google would show anything.
It looks like there could be some enthusiasts after all:
http://www.automotiveforums.com/vbulletin/showthread.php?t=117942
(I like the first smiley in the tread...)

Here is British version (steering wheel on wrong side)
http://www.ak-miramare.hr/baca/vslike/zanim/yugoeng.jpg

Back around 1987, I was shopping for a commuter car, as my '79 International Scout was draining my wallet in fuel costs. The Yugos were only recently introduced in the US, and dirt cheap (<US$5K), so I went to the local dealership with my friend to check them out.

After making jokes about their quality, we decided to see how heavy they were. With our backs facing the car, we both grabbed the underside of the rear bumper and lifted. Well, the bumper BROKE!...

Needless to say, I didn't buy one...

beerchug

-Eric

Gee Eric

Didn't they have a sign...

"You broke it, you bought it"???


Local Ford dealer sold Yugo's for a while. May have sold a couple of hundred. Wouldn't sell the last twelve. He needed to hang onto them for parts, as he couldn't get any from overseas.

Ford's better Idea, be able to supply parts...

regards...casey