one
You can short-connect the second and third pins of the USB serial cable in your hand, open the serial port debugging tool, go to the interface of serial port debugging Assistant, and set the corresponding communication port. Then right-click my computer and choose \"Management\
two
After setting up the communication port, enter a few characters in the input window and click the Manual Send button. If the content of the receiving display area is the same as that of the sending area, it indicates that the communication from the usb to the serial port is normal, and vice versa.
three
When testing, it must be noted that the 2.3 pin short of the serial line must operate in a correct manner and cannot be short-circuited with other pins, otherwise the test cannot be completed.