4. Select the correct product model, correct transmission method, correct serial port number, correct baud rate, and set the control correctly according to the portable LED display control software and the control card of your choice. Address bits and baud rate on the system hardware.

5. to ensure that the portable LED sign control system hardware has been properly powered.

6. If after the above check and correction still occurs, please use a multimeter to measure if the serial port of the connected computer or control system hardware has been damaged to confirm whether the computer manufacturer should be sent back or return the control system hardware. Related manufacturers testing.