data transfer between s7 300 and PC

hi,
i want to transfer some data from a s7 300 to a pc.
what is the easiest (and chipest ) way for it.
do i have to use siemens a CP card or a aplicom card?
the transfer does not have to be be quick, i just want to transfer some data blocks to a pc one a day. mpi and profibus are rs485 based protocols, is there a way to transfer this datas via a rs232-485 converter?

The easiest way is ethernet, if the cpu is equipped with it. Otherwis you need to connect an rs232/mpi adapter or usb/mpi adapter.

with a usb(or rs232)to mpi converter, i can see the data blocks via simatic manager, but i have to take the blocks via a program i will write and show them as spread sheets. i am recording the tag times of some stations on a production line, and production engineers need this data. so i want to design a user friendly system for them to archive this datas.how can i take this data to my program via usb-mpi converter?

Then you need to use a simatic driver dll, like prodave, MHJ ComDRV, or a freeware libnodave. Or check my product. It does exactly what you need.