Hi Greg,

Not sure I fully understand but there are lots of examples on the arduino playground and stackoverlow etc.

I'll add a few quick tips if I understand correctly.

1)

The Arduino code doesn't compile into a windows dll and is always uploaded to the Arduino processor via usb or some other means. The arduino code is capable of sending and receiving Serial.

2)

I expect the scanner is connected to some arduino pins and has a library or some sample code. In that case you can combine the reading and printing of serial on the arduino with the scanner code.

3)

The Vb windows app can use the System.IO name space to read or write to a windows serial port. So your vb app can show UI controls, buttons etc and can forward the commands via a SerialPort such as COM1 at an agreed baud/speed defined in your sketch when you issue a Serial.begin(baudRate) in your arduino code.

Remember that the debugger uses the serial port, this might not be relevant but if it is then post a question and I will point you to a solution.

I hope this helps, there are tons of examples out these for the .NET SerialPort class. You don't need C++ on the windows side of things unless you need pin level port control. 

Hi, Yes that makes good sense to me.

Best of luck