siemens plc.

hi everyone!
i am quite new to the plc.i have knowledge regarding siemens s7-200 software i.e. step-7 micro/win and as such i can make programs well.the problem that i stand is i hav very less idea regarding its hardware,like how to rectify if some hardware failure is detected.i want to learn basics about hardware of plc.
please do let me know if there's any site realted to hardware testing.
any help would be appreciated.
thanks in advance.
vik.

With the S7-200 hardware I have used so far, there was only the classical way to find hardware trouble: compare the state of the logic in the program to the state of inputs and outputs and figure out what is wrong. Maybe the newer, more complex cards, such as Ethernet interface and so on have diagnostic possibilities and then the first source to turn to is Read The Fine Manual.

Regards,