PLC=Programmable Logic Controller
Most have gone triac as opposed to conventional relays, although the one in class was probably a little older(the ones at my tech college were..... well they needed replaced...)
As for the language used to configure/program, those vary greatly, different manufacturers=different languages/software mediums. I would have been better off had I learned C++ or JAVAscript, you can do all kinds of neat things with a Smart Server with JAVA!
Just food for thought... Hope that helps!