1. Right-click My Computer, and then click Open Device Manager;

2. Find the ports (COM and LPT) in Device Manager and click the "+"in front, then click Open Port;

3. Double-click the communication port (COM5) or right-click and click Properties to open the properties of the communication port;

4. In the properties of communication port (COM5), click port settings;

5. Click Advanced Options, com port number, and then click the drop-down menu to select the required serial number.