How to rectify EMC issues caused by serial communication interruption in HMI (Human Machine Delivery System)?

EMC remediation for HMI serial communication interruptions requires a systematic approach to pinpointing the interference coupling path. First, determine the conditions under which the interruption occurs: during ESD, EFT, Surge, or RS/CS testing. Use an oscilloscope to monitor the TX and RX signal lines of the serial port, observing for waveform distortion, glitches, or level shifts when interference is applied. Common causes include: insufficient protection leading to transient overvoltage that damages or latches up the transceiver chip; common-mode noise causing signal ground potential fluctuations exceeding the receiver's common-mode input range; and spatial radiation coupling to the communication line or the chip itself.

Remedial measures can be tried sequentially: adding or replacing higher-speed TVS/ESD protection devices, such as ESD5V0D3B, on the serial port signal and control lines, ensuring proper grounding; adding series resistors or ferrite beads on the signal lines to suppress high-frequency interference; adding common-mode chokes to suppress common-mode noise; checking and optimizing the shielding and grounding of the interface connectors; covering the serial port circuit with a partial shield; and adding data verification and timeout retransmission mechanisms in the software. If the problem is caused by a ground loop, consider using an isolated serial port chip. Through gradual testing and reinforcement using the protection and filtering components of Yinte Electronics, the problem of serial communication interruption can usually be effectively solved.