PC control

i desparate need source code in Vb or C,C++ (prefferablly in VB)to control LPT or Serial port, in order to count revolutions,0V - +5V and start a counter.It is very important for me.

It's unlikely you're going to be able to use VB to count pulses on an I/O pin of a PC port with any decent speed. If I had such a challenge I'd spend a couple of bucks on a hardware device that communicated with a simple protocol to a COM port.

This might be of interest to you:

http://www.weedtech.com/wtpct-m.html

If I were you I would program an 8051 or any relative microcontroler pic type for example and communicate with pc using vb and mscomm activix there is a good routine named as com event which can realy help in data recieving (sending is much more easier ) this way would be rather inexpensive.
If you are not informed about microcontrollers you can use a usart instead as a serial to parrallel device.
using the LPT port with VB ?
I think you must use VC with that