How Can I Find Value is Come From Keyboard or Barcoder Reader in VB.NET

If you're using a "keyboard wedge" bar code scanner, you can't. To the system, it appears as if the barcode was coming from the keyboard.

The work around for this requires you to configure the barcode scanner to send prefix and postfix characters to the barcode when it scans a barcode. You then have to set the "KeyPreview" property on your form to True and write code for the forms KeyDown event to look for and track the progress of the barcode prefix characters. Once you have seen that prefix, you can gather up all the keypresses in the barcode until you see the postfix characters. Then you've got your barcode.

If you REALLY want to seperate the two without jumping through flaming USB code or specially coded forms, use a barcode scanner with a different interface, either Serial or Ethernet based. It makes thing a lot easier to tell where things are coming from.