How to isolate the communication ground and power ground of the power measurement switch (PMS)?

If the ground of the PMS internal communication circuit (such as RS485, CAN transceiver) is directly connected to the power ground (main power ground), high-frequency noise on the power ground will severely interfere with communication through the common impedance, leading to bit errors. Isolation is an effective means, commonly using magnetic isolation or optical isolation. Magnetic isolation: Use a communication transceiver chip with isolated power supply (such as ADM2587E), which internally couples the signal and power supply through a transformer to achieve complete electrical isolation between the communication ground and the power ground. Optical isolation: Use an optocoupler (such as 6N137) to isolate communication control signals, but independent power supplies must be provided to both sides of the optocoupler. In implementation, the primary side (connected to the MCU) of the isolation device uses the control power ground (DGND), and the secondary side (connected to the communication interface) uses the isolation ground (ISO_GND). ISO_GND should be connected to the protective ground of the communication port (through a Y capacitor or directly) and maintain a safe distance from the power ground (such as an 8mm creepage distance). A common-mode inductor CMZ2012A-900T needs to be installed at the output of the isolation power supply module for filtering. Through isolation, the noise voltage between the communication ground and the power ground can be suppressed to above 1500V, ensuring stable communication.