Connecta S7 300 with VB without OPC Server

DEar All,

I´m trying to develope a little application (like a little Scada) inwich I have to communicate my PC with a PLC Siemens S7 300 via Visual Basic.
I understand I could use an OPC server but is out of muy budget. I read something from "DesertDog" saying it is possible to do it witho out any extra sofware.
COuld any body tell me somthing more about it?
thank you very much

The only free driver for S7 communications is libnodave. All the orther drivers are not free. (Simatic Prodave, Deltalogic, MHJ, etc)

Assuming your S7-300 has an ethernet card, you wouldn't need a canned "driver". A cursory knowledge of sockets would be enough to communicate with VB directly.