The Device Emulator provides two serial ports (virtual COM ports) that you can map to COM ports on your development computer. To display the Configure Emulator Properties dialog box, click Options on the Tools menu, click Device Tools, and click Devices. In the Devices picker, select an emulator and click Properties…, then click Configure… on the Emulator Properties dialog box.
To expose the functionality of Serial ports, use the SerialPort class, which represents any resources available through the serial port. You use this class to perform synchronous I/O over a port.