Hello.
If you have the specifications or at least the Model number for us we can surely help you somehow.
If the sensor is connected using the Serial Port you'll have it easy, since VB.NET has an own class for writing and reading to the serial port (SeiralPort). If it's connected using USB you'll have to write a driver, 'cause I don't know a way to speak with a USB-Controller directly from .NET (if I'm wrong here, then please tell me, I'd really love to know that!),
If it's connected using the Parallel Port...I have no idea.
Bobby