How to use COM port to convert USB cable;
1. First, prepare a USB to serial cable. It can be seen that one end of this cable is a standard USB port, which can be connected to the U port of the notebook, and the other end is a standard 9-pin serial port male terminal, which can be connected to the target device;
2. Then install the driver of USB to serial data line. The driver files are usually on the CD attached with the data cable, or can be downloaded from the Internet.
3. Double-click the driver installation file to install the driver on the notebook;
4. Insert the USB-to-serial data cable into the idle USB data port of the computer;
5. Because the serial port added by this data cable is generally not the default serial port 1, it is necessary to find the serial number of the new serial port first. Turn on my computer;
6. Right-click my computer and select Device;
7. In the port options, you can see that the new serial port is COM 7；;
8. Open the serial assistant software and select COM 7； in the serial number position;
9. Click to open the serial port, and you can see that the sign light is on, indicating that the serial port connection is normal. So you can debug the equipment through this new serial port.