PLCs??!

what r PLCs?
I know, Programmable logic controllers.

I took 2 courses in the uni about PIC microcontrollers so im not a beginner in the stuff. But the question is, do i have to take any courses in PLCs? becoz sm of my friends have registered in a course about PLCs but they dont know anything microcontrollers. Do i have to do the same?

Well Programmable logic controllers and PICs are all together different

Though you can use a PIC to make a PLC

PLC is a device (and not a component like PIC) which can be programmed (basic language Ladder diagram programming, altough now it can be programmed in FBD (function block diagram), sequential charts, BASIC, and C depending on the kind of PLC)

PIC and PLC courses will be altogether differnet
and Normally PLCs are used in industrial automation

http://www.plcman.co.uk/plc/
just search on google with "plc basic" and you will find a whole lot of information.

And regarding taking courses in PLCs then it epends on your field of application, If you plan to go in automation then course on PLC, DCS (Distributed control systems) is required

Try

https://www.plcs.net/contents.shtml

If you want to work in industry, especially as an engineer, it is a good Idea to learn about PLC's. They are not especially hard to understand. As Instruite pointed out, You will learn the concept of ladder logic, and how relay contacts can be timed in sequential order to activate single or multiple output devices. PLC's are used in almost every proccess operation imagineable, and understanding them can lead to a better understanding of digital electronics.

you can try downloading PLC software and manuals to see what they can do. I would suggest something small and free for start (and with simulator). you can get controllers cheap from eBay to get the real hands on experience.