The USB cable of the sending card is not connected. Try again after connecting.
2. The USB driver of the sending card is not installed, check the computer settings, reinstall the software or install the USB driver separately.
3. The USB port of the computer is faulty, replace another USB port, or replace the control computer and try again.
4. The USB cable connected to the sending card is faulty, replace the USB cable.
5. The sending card itself is faulty. Replace the sending card and try again.