<b>Moderators Note:</b> The following questions were originally four separate posts to the forum by the same author. They seem related to me and so I combined them into one post.

What is the difference between PLC and relay?

What are the different control systems used in automation?

What are the different components used in automation?

What type of sensors are used in measuring?

 

Hello Sakshi,

These are the basic questions who's answer you can find easily in any basic instrumentation & control book.

As par the policies of most of good forums: THOSE FORUMS ARE NOT TO ANSWER HOMEWORK QUESTIONS OF GRADS AS THESE READY MADE ANSWERS WILL ONLY PREVENT THERE INHERENT INTELLECT TO DEVELOP.

So, a note for the moderator. Please help people to do some homework and not flood the site with KG questions as this site is for Nerds who are more than ready to help who did there best before coming to here.

As one can see you, just type in Google some keywords related to automation and you will be flooded with answers. If someone doesn't understand something particular than he/she's most welcome. I hope my suggestion would taken into consideration by moderator in constructive way.

Regards
Sushant Chanana
sushant.chanana [at] sedl.in

 

PLC is basically and programmable controller that can implement the s/w based application and also store the data in its memory for further analysis.

The limitations of only discrete controlling is not bond wth PLCby using relay u can have digital controlling.

PLC still implements it's digital logic using relays. PLC contains memory but relay don't. Relay based ladder logics are more complicated and difficult during any updation but in PLC it's too easy.

PLC can use not ony for digital control but for Analog signal controlling also.

 

All that being true, Sushant, we probably ought to give Sakshi some homework. Here are my picks for some very good introductions to automation and control:

The Automation Body of Knowledge, edited by Vernon Trevathan, 2nd Edition, ISA Press, www.isa.org/books

Process Automation Handbook, by Jonathan Love, Springer Verlag 2007 (really great book) http://www.amazon.co.uk/Process-Automation-Handbook-Theory-Practice/dp/1846282810

My own Instrumentation Reference Book 4th Edition (forthcoming in September) Elsevier www.elsevier.com

And for a little bit more in depth, Bela Liptak's _The Instrument Engineer's Handbook_ CRC Press www.isa.org/books

Good luck, Sakshi. Please read and report back.

Walt Boyes
Editor in Chief
Control and Controlglobal.com
www.controlglobal.com
Mailto:wboyes[ at] putman.net
Read my blog SoundOFF!! At www.controlglobal.com/soundoff

 

Hi Walt,

I think Hugh Jack's book might be a better bet for the poor student, it's free. http://www.eod.gvsu.edu/~jackh/books/plcs/. Those others are pretty spendy especially for me.

Regards
cww