IDTech Windows SDK Guide  1.2.165.1
API reference for VP3300
Initialize VP3300:

A Singleton instance has been established in the IDT_VP3300 class. Establish the callback, and then access the VP3300 through USB via the SharedController instance.

public VP3300_Simple_Demo()
{
InitializeComponent();
IDT_VP3300.setCallback(MessageCallBack);
}