s7 300 subroutines is there any ??

hi guys and sorry if this question seems to be like a very basic question, now is there any subroutines in s7300 plcs similar to the onee found in s7200 ?? I am familiar (very familiar) in programming s7200 plcs microwin, and trying to start out with step 7 lite, but I am not sure where to write my program ...I mean this step 7 has alot of terms and I dont seem to understand any...like OB(organization blocks),FCs (function blocks),elc,etc,... now which one of these blocks can I use as a subroutine ??? and where can I write my main program as I always do in s7200??

now I am reading that manual and still not really understanding..
I am sure you guys will help me understand in simple terms..


regards.

You can regard FCs and FBs both as being subroutines which are called (usually) from OB1.

If you have a very simple program you could write it entirely in OB1, but normally you'll divide your program um into units which you then write in FCs (if you don't to store any results for the next cycle) or in FBs if you do need to store values from one cycle to the next. These are then called from OB1.

In these FCs and FBs you can then call other FCs and FB as further subroutines.

What you can't do is call subroutines in a re-entrant fashion, as you could, for example, in a PC program. There again, I assume you can't do that with the S7 200 either.

Hope this helps

Regards

Roy

ok RMA thanks for the help, I think I got it..

regards.Farid