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TIDY
March 4th, 2004, 11:00 AM
Can anyone tell me what the advanatges and disadvantages of current and voltage inputs and outputs for plcs, and the differences between the two? nice one, cheers!!!!!!

Guest
March 4th, 2004, 11:20 AM
Look on page 38 of your textbook.

TIDY
March 4th, 2004, 11:30 AM
yeah nice one, seriously though!
its for a project you see and i know nought about it!

Guest
March 4th, 2004, 11:36 AM
Is this how they teach students to do research these days?

TIDY
March 4th, 2004, 11:45 AM
yeah part of it, is that ok with you

Guest
March 4th, 2004, 11:50 AM
No not really. Why not just ask your instructor.

AnotherGuest
March 4th, 2004, 12:01 PM
Here you go.

www.vir.edu

kamenges
March 4th, 2004, 12:05 PM
TIDY-
I generally decreases my faith in the human condition when a question like this is posed. It shows lack of effort and forethought regardless of whether one or both of those things are true. List what you know about this topic and narrow the scope of your question. You'll get alot better response. And, yes, the Internet is supposed to be a source for stuff like this. However, your topic has reams of written text on it already. You might be able to find something quicker on Google than wait for someone here to answer.

'Guest'-
It's bad form to take shots at people and remain anonymous. that's what terrorists do. Sack up and sign in.

Keith

TIDY
March 4th, 2004, 12:41 PM
up yours!

kamenges
March 4th, 2004, 12:49 PM
So, just to clarify, is that:

'No, I don't know anything about this subject'
or
'No, I didn't expend any effort or use any forethought'

Just curious.

Keith

TIDY
March 4th, 2004, 12:52 PM
don't know a thing about it, its ok now i know wat it is, i just copied someones, easy peasy!

Bitmore
March 4th, 2004, 01:07 PM
I suppose I'll try a little, seems to me with all the typing going on trying a little is just that.

Current Inputs/Outputs
Typically more electrical noise/interference resistant. A more robust method. In some PLC like A-B current I/O vrs. Voltage usually offers more resolution ie. 32767 instead of 4095 (bit resolution).
Can typically be used in longer wire runs. Harder to troubleshoot in the field. (must use inline current meter to monitor activity)

Voltage Inputs/Outputs
Not very noise immune. Shorter wire lengths do to resistance in wire vrs. noise. It is easy to implement and troubleshoot (simple voltage meter to monitor activity). Most PLCs only offer 12 bit resolution of 4095 max.

Hope this helped
Bitmore

Steve Bailey
March 4th, 2004, 01:13 PM
Tidy,

Sometimes it's easier to understand electrical phenomena by comparing them to things you already understand. Quite often electrical terms are compared to fluid terms. Voltage is similar to the pressure in a pipe, whilst current is similar to the rate of fluid flow.

Consequently, voltage signals do a more accurate job of measuring physical phenomena like pressure, force, or weight. Current signals more accurately measure physical phenomema such as fluid flow (gallons per minute) or speed (miles per hour).

Don't take those other guys too seriously. They just like to harass students. As always, be sceptical of information you get over the internet.

rsdoran
March 4th, 2004, 01:15 PM
I dont agree with what Guest did BUT

TIDY you, and those like you, are why the members here do NOT make an effort to answer questions like this. It is also the reason much of the ridiculing is done.

I take you learned alot that way, hopefully what the other student wrote was correct. Obtaining and turning in assignments in this fashion is lazy and non profitable. In due time some of this information will be needed at a later date.

Sad thing is you will probably graduate and do things....if this is a real indication of your character I hope its running the french fry machine at McDonald's.

What a waste of time and money.

Rube
March 4th, 2004, 02:18 PM
That must be an example of a current input--cause it shocked me.

Wonder how much help you get when you ask questions that way? We might need a banner across the new posts page that asks "Have you tried to help yourself first?"

elevmike
March 4th, 2004, 02:25 PM
And on to another thread.....

TIDY
March 4th, 2004, 04:07 PM
i'll have you know i work full time at airbus UK as an engineer, and been doing day release for the last four years, so theres no need for your smarmy comments

TIDY
March 4th, 2004, 04:16 PM
thanks Bitmore that was all i needed to know, just couldn't find the pro's and con's of the two types, sorted.

oh i didn't copy just reeling you all in, a good bite.

elevmike
March 4th, 2004, 04:50 PM
TIDY,

Here in Detroit the words "Day Release" conjures up images of mid/low security prisoners on Day Release programs. That’s when they get to go to their jobs in the day and have to return at night for lock down. :(

Somebody might get the wrong impression from your last post.

4 years is a long time for a day release prisoner? utoh

Anyway Steve and Bitmore answered you question.:thumb:

Good luck with it!

Mike

TIDY
March 4th, 2004, 05:11 PM
A day off work to go to college! its not that hard to work out.

rsdoran
March 4th, 2004, 05:25 PM
This guy has rubbed my chaps a little.

The guys that cleans the toilets and takes out the trash is OFTEN referred to as the SANITATION ENGINEER.

I have not nor probably will ever have the title of Engineer, if you are an example I NEVER want it.

You can say what you want about comments etc...if you KNOW then contribute...if you dont then phrase the question properly to get an answer. Your are asking, you must participate to get an answer.

corkers
March 5th, 2004, 04:59 AM
Not only is this guy lazy but he gets paid to be lazy...

Typical $%^@ engineer

Leonardo2003
March 5th, 2004, 06:24 AM
Originally posted by Steve Bailey
Tidy,

Sometimes it's easier to understand electrical phenomena by comparing them to things you already understand. Quite often electrical terms are compared to fluid terms. Voltage is similar to the pressure in a pipe, whilst current is similar to the rate of fluid flow.

Consequently, voltage signals do a more accurate job of measuring physical phenomena like pressure, force, or weight. Current signals more accurately measure physical phenomema such as fluid flow (gallons per minute) or speed (miles per hour).

Don't take those other guys too seriously. They just like to harass students. As always, be sceptical of information you get over the internet.

Sir,

I really appreciate the sample you made and the analogous for this is quite easy to understand.

As far as my concern, no matter what applications you make such as pressure, weight or etc... it doesn't mean that voltages nor currents are use for specific applications as you mentioned earlier. For my opinion, the use of voltage signal should be used for short distance applications so to minimize the voltage drop. If your instruments your going to use is very far to each other, I guess current should be used for accurate reading. Avoiding noise can be eliminatd easily rather than voltage drop.

In Summary, voltage can be used for short distance applications, for long distance applications, current is advisable.

Hope my opinion is correct...thanks

Have a nice day.

kalle
March 5th, 2004, 06:43 AM
Leonardo, me think that you should read Steve's last paragraph one more time. Especially his last sentence......

Don't take those other guys too seriously. They just like to harass students. As always, be sceptical of information you get over the internet.

Some of the guy's here could change career and start writing instead!

guest
March 5th, 2004, 11:45 AM
You go boyo :)

drewcrew6
March 5th, 2004, 12:00 PM
What amazes me the most of most people with a "Engineer" title is the total lack of profesionalism. You would think in a new post on a new board from a new person you would putforth a certain degree of professionlism to show what kind of person you are.(But not limiting to here, also life in general). Instead of a total disrespect for those you are asking help from. Once you have earned some of your own respect from others then you can step back a little and loosen up but not until then.



Drewcrew6

Mtn_Bkng_Dave
March 7th, 2004, 12:28 AM
INJUNEAR I-N-J-U-N-E-A-R
See.......I are one.......

Geez whats the world coming to....

:D

Leonardo2003
March 7th, 2004, 03:21 AM
Originally posted by kalle
Leonardo, me think that you should read Steve's last paragraph one more time. Especially his last sentence......



Some of the guy's here could change career and start writing instead!

I think he's talking about his personal point of view regarding the behavior of a certain person... on my case I talking about the topic, which is voltage versus current...

Thanks for the comment...

dandrade
March 7th, 2004, 05:03 PM
Outputs corrent more speed off voltage.Is commun A/D chips.
Saídas em corrente são mais rápidas do que em tensão.

TIDY
March 8th, 2004, 03:37 PM
The reason for asking the question in the first place was because most web sites are trying to sell plcs rather than explain how they work.
oh and i build wings for aircraft, not clean out toilets!!!!!!!!!

boyo!

Sleepy Wombat
March 8th, 2004, 06:40 PM
So you work for Airbus at the Brougton Plant in Flintshire manufacturing wings... thats scary... :D

Ashwin
March 9th, 2004, 05:35 AM
Maan..you drew more attention than that jessica( i mean in terms of posts) I began to get a complex that if I dont post at this forum i will be thrown out from PLCs.net. I will chose to refrain from commenting coz I am too inexperienced compared to the strength of this forum. but anyways...hope you are having fun with all the attention you are getting!!! enjoy it while it lasts..

been there done that!!!

Xion
March 9th, 2004, 09:45 AM
That's one problem with mostly USA and the UK. Anyone can call themselves an Engineer, anyone at all. I spent 4 years at university studying for my degree and now I'm a full-time Engineer my education hasn't stopped.

I don't have any special title, but I call myself an Engineer.

However, Mr John Smith down the street can call himself an Engineer with no qualifications at all. Someone can call themselves any Engineering title they want. I'm not saying university is the only route to being an Engineer but I wish there was some formal route for everyone for the good of all True Engineers.

That means that the occational un-professional "Engineer" gives the people that have studied a bad reputation.

In Europe they do things differently. Doctors are called Dr. Smith, Professors are called Prof. Smith and Engineers are called Eng. Smith.

Wouldn't that be nice? :)

LadderLogic
March 9th, 2004, 10:05 PM
And uniform! How about some dashing tunic with shoulder boards, color lapels (red for M.E., black for E.E., yellow for Ch.E. etc.)? And a cap or, better yet, a shako with a plume... And a sword - or a dagger - or a gold-plated screwdriver at least. Wouldn't that be nice? Women, for once, will certainly appreciate that. Beats that nerdy pocket protector thingie... ;)

You may treat "engineer" as a title or as a type of job done. That is the difference here. There is a "title" thing in the U.S., it is called "P.E." - "Professional Engineer", but it is not required for all but a few of the engineering positions.

One may call himself whatever he wants. What matters is if he is able to perform certain types of work at certain level.

TIDY
March 10th, 2004, 03:42 PM
does anyone else want to have a dig then, i'm gonna set a record in messages here.
all i asked is a simple question, wat do you all do then, talk about plcs all day, sounds fun i'm gonna give up my job and join you. whats the money like? :D
I work at Filton not Broughton, making Airbuses, the worlds leading aircraft manufacturing business.