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First, confirm whether the battery's BMS communication protocol matches the inverter's. If not, only US2 mode can be used.
Second, check whether the wiring is correct. Refer to the user manual.
Finally, check whether BMS protocol is set correctly after program 05 is set in Li mode.
If 20 faults occur after the inverter has been used for a period of time, it is necessary to check whether the wire or the terminal block is oxidized, causing poor contact. You can try unplugging and re-plugging it. It may be that the communication board is damaged, and this needs to be confirmed by replacement.
