ZylSerialPortAX 1.4

ZylSerialPortAX is a thread based asynchronous serial port ActiveX control.
Use ZylSerialPortAX control to easily communicate with external devices on serial port connection, such as modems, bar code readers, GSM modules and others.

You can use it also with USB, IrDA and Bluetooth devices, because these devices have a driver that redirects the input from the USB, IrDA or Bluetooth port to a virtual serial port (you can check it in System/Device Manager/Ports). If your USB device is not provided with such a driver, then use a USB controller whose vendor provides a virtual serial port driver, such as FTDI or use a USB/RS-232 adapter.