Using VB with BV4221
Resources : VB Source code i2c-Generic.zip
The BV4221 USB to I2C is simply a COM port device. When the FTDI drivers are installed it works as a virtual com port and so driving with software is a matter of sending and receiving commands from the COM port.
This simple program provides a terminal in which to send and receive commands. As can be seen form the screenshot the BV test command has been entered and the incrementing bytes have been received. The actual program is no more useful than a terminal but it does from the basis of writing other programs.
I has been purposely kept simple so that is can be modified more easily by the user. The source code is written in VB using the free express edition and all of the various folders it creates are in that folder. If you just want to test it out then the exe file is in then \bin\Release folder and is called i2c.exe.