How to avoid crosstalk between multiple communication interfaces of a power FTU?

To avoid crosstalk between multiple communication interfaces, isolation and frequency division are employed.

Interface isolation: RS485, Ethernet, and wireless modules are powered by independent power supplies (WRB2405S-3W).

Signal isolation: Interfaces are connected via TLP281 optocouplers or ADUM1410 digital isolators.

PCB layout: Interfaces are placed in separate zones with a spacing greater than 20mm and a grounding guard ring in between. Cables are routed separately to avoid parallel runs. Software-wise, peak traffic periods for each interface are staggered.

Through these measures, crosstalk between interfaces is less than -60dB, each communication operates independently, meeting the IEC 61000-4-6 multi-port conducted immunity test requirements.