How to improve the interference immunity of serial communication in power DTU?

Improving the immunity of DTU serial communication requires enhanced protection and isolation. A 22Ω resistor should be connected in series on the TX/RX lines for current limiting, and a TVS diode (SMBJ6.0CA) should be connected in parallel for protection. Signal isolation should be achieved using optocouplers (such as TLP281) or digital isolators (such as ADuM1410). Shielded communication cables should be used, with the shield grounded at one end. On the PCB layout, the serial port circuitry should be kept away from the power supply circuitry. Testing should meet IEC61000-4-2 ESD ±8kV and IEC61000-4-4 EFT ±4kV. After improving immunity, the serial port's bit error rate should be below 10^-6 in noisy environments, and the communication distance can be extended to 1.2km.