Student in need

Hi everyone,
I'm currently studying PLCs at college and have got an assignment to hand in today, can anybody suggest some answers for this question:
Name and Describe the various types of media used for communications (i.e. types of wire etc) in a modern PLC controlled system.
Any help i can get would be great.
Thanks,
me

sorry i cant help ya mate, good luck anyway
j98

Try saying something about protocols and connection types. like just because you can call france, doesn't mean you can talk to them you know.
i dunno, gonna go play cs:s now.

Hasn't this material been covered in lecture or your text book or course materials?

Try checking out some of the major PLC manufacturer web sites. (AB, Siemens, Modicon, GEFanuc, etc...) There are many protocols and associated media available and you should do the research yourself instead of having it handed to you on a silver platter. Next time don't wait until the last minute.

Good answer

Hydro Power Guy said:

Try checking out some of the major PLC manufacturer web sites. (AB, Siemens, Modicon, GEFanuc, etc...) There are many protocols and associated media available and you should do the research yourself instead of having it handed to you on a silver platter. Next time don't wait until the last minute.

Click to expand...

Good answer there Hydro. Waiting until the last minute alwasy gets you in trouble......

Maybe some of you have forgotten...

First and foremost Unregistered your question was too poorly phrased to offer am appropriate response.

Phillips link provides a lot of info. The main thing about communication is it can involve wiring standards and protocols, in some cases either of these may be proprietary. Even today the use of Ethernet may differ from brand to brand. Some of the more common forms are Modbus, Profibus, CANopen..others will probably chime in with more. Originally most plcs used either RS232, RS422 or RS485 wiring standards but may have used a proprietary protocol..AB has Df1, DH485, DH+... GE, with the Series 90, uses an RS232/422/485 connection with SNP.

NOTE: To those that commented without answering. Have you forgotten?

I am sure many of you had some of the same issues when in school that students have today, now that I am full time I can see some of the issues students have to deal with.

To give everyone an idea and maybe refresh some memories. I am presently enrolled for 15 credit hours in a 9 week summer semester. All the classes are accelerated. My German class basically covers a chapter in 2 classes (on Monday and Wednesday) with a test on Friday. A Journal from the workbook and homework from videos (listen too and translate what is said) also due on Friday. I have a 700 word essay for English Composition due on Saturday and a 4 chapter Psychology test on Monday. I havent even mentioned having a class WITHOUT A BOOK with exams next week.

Have you forgotten....those 300 page reading assignments, the 500 (1000 or 2000) word essays/summaries due in 2 days (or less), research requirements, lab time, missing a day (no notes), work and study time clashing... I am sure some of you can remember more.

The student(s) may be lazy or pressured, I dont know. I am sure it will be some of both.

When I was in elementary school I wore glasses (still do) so got called 4 eyes, kids can be cruel. If you look at what is being (has been) said here maybe you can understand where the kids get it from.

As professionals doesnt it make more sense to talk WITH the person(s) to determine a way to help them help theirself? This may be someone you work with or FOR in the future.

The end.

No, I have not forgotten.....

The student(s) may be lazy or pressured, I dont know. I am sure it will be some of both.

Click to expand...

I have not forgotten what it is like to be a student. I worked a 40+ hour a week job and attended evening classes until my degree was completed. This left very little time for homework or school projects but I still managed and kept a 3.9 GPA.



School is what you make of it. You can go through the motions to get the average grades or you can apply yourself and ace.



What can I say this is just one mans opinion.

I admire your empathy, Ron. I'm just not sure it was deserved in this case.

I must admit I was tempted to give the original poster some grief, but I withheld partially out of laziness, partly out of empathy, but mostly because I figured it would be pointless. The guys that understood wouldn't need my response, and the guys that could benefit wouldn't understand it.

It wasn't the question itself that irritated me. It was the "...an assignment to hand in today..." remark. Why should that be my problem? The questioner will, at some point in his life, figure out that his failings aren't my fault and compensating for them aren't my responsibility. His mother might respond to this plea for help, but I see no reason why I should encourage his delusion!

I know this is futile

A prime example of what I call the "I AM GREAT" syndrome. I guess it will always be the right thing to talk abusively to those just trying to learn. Not all people are capable of learning at the same pace or level.

First comment made on a question like this is "read the textbook". What if the textbook doesnt offer what is used now? Example: HNC study guide: www.freestudy.co.uk Lets say its a Research assignment....WHAT is wrong with asking those that WILL know? Once you get the names like profibus, modbus etc etc you can look them up?

The site is also about LEARNING PLCS...even has a section on it. Shouldnt students come here to ask questions? Shouldnt they be welcomed and advised on how to ask questions if they ask one that is improperly phrased? What if an elementary teacher told one of you kids something like what is stated here?

Tom you posted while I was typing. The "turn in today" is nothing unusual though, that was my point. Its not unusual to be given an assignment that has to be turned in the next day or so. All I am saying is that in most cases they are young and making an effort to learn...WHO BETTER TO LEARN FROM THEN THOSE THAT DO? If they make a statement or ask a question improperly then why not tell them what they have done wrong instead of just being mean?

PLC.net is undoubtedly the best forum online with some of the best professionals you could find. I just dont believe the professionalism is being used when dealing with students.

Teetering on the fence...

I agree with both sides of this issue to an extent, but mainly, because a student may be late on an assignment doesn't mean that he is lazy (possible, probably, but still just an assumption). The fact is, many here offer much help to students. However, none that I have seen have directly handed over the homework. Henceforth, my quandary is this;

Yes we will “help, not give”, (this is fine) if you ask correctly (not good).

No we will not “help, not give” (presumptuous) if you don’t phase your question correctly (arrogant).

This is how I see the situation, and I also, unfortunately, have given the “no” answer here in the past for that reason. Sorry, because I do remember the stressful time constraints from the college days. How many of you NEVER crammed for an exam? We all have a little procrastination in us, some just more than others.

In summary, since we never just “give” the answers, why not help all that ask?

Any student who comes here and shows that he has at least made some kind of an effort is going to find a lot of help. The guys who are just looking to have it handed to them are another matter.

I finished school 14 years ago. I was 28. I had to work my way through, first as a full time student/part time worker, then as a part time student/full time worker. I paid my own way from day one, I had no choice, and it took time. Yes, I remember the pressures and struggles. But after school one does not find relief from the pressures. If anything, they intensify. I've worked with too many guys who coasted through school, mooching off the work of others, and guess what, in the workplace they do the same thing: mooch off from others. The original poster never offered what he had done so far. Suppose he had just mentioned a couple of kinds of media used and then aksed "what others are there?" Or asked is "such and such used? what other things might be used" I suspect that he would have received an entirely different reception.

I wasn't going to chime in until I got about half way down the list of posts...

While the question was phrased in a way that my initial response was 'no' I must admit that a re-read left me wanting to be at least partially helpful. If the question had been posed by someone who'd taken the time to register it would have been an immediate 'partial'...

I can remember well showing up to the first day of class (more than once) and having the professor start off with "The book is out of date, if you bought it return it because we won't be using it; the university required that it be listed for this class." From that point on if I needed help with an assignment I had my notes, the professor (when in his office, which didn't line up well with my schedule most of the time), other students, and (gulp) asking the engineers I worked with in my part-time (now full time) job who were IEs, AgEs, and MEs, but not EEs.

I guess the short version is that after reading Ron's post I have to at least partially agree with him; there have been times when I think all of us have treated students (and their questions) in a less than professional manner, myself included.

All that said I can't say that I really disagree with the other comments made here... so...

Now to answer the question at hand...

Some types of Media:
CAT3, CAT5, Twisted Pair, Coax (both 'thicknet' and 'thinnet'), Wireless (proprietary), Wireless 802.11a/b/g, Fiber Optic, etc.

Some types of Protocols (even though it wasn't asked for):
RS232, RS422, RS485, ModBUS, ModBUS TCP, Proprietary (DirectNet, K-Sequence), CANBUS, etc.

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