CAN/RS485 communication between ARK BDC/HVC controller and Growatt inverter has failed. Battery will not charge or discharge. BMS ALM LED flashes red.
Common causes
INV port cable not seated at BDC controller or at inverter COM portWrong pinout — Growatt uses specific INV port wiring (RJ45 pin 7=RS485_B, pin 8=RS485_A)Battery type not set to 'Growatt ARK HV' in ShinePhoneProtocol mismatch between ARK series and inverter firmware
What to check
STEP 1
Check INV port cable from BDC controller to inverter COM port is fully seated at both ends. This is a Growatt-specific RJ45 cable — pin 7=RS485_B, pin 8=RS485_A. Standard Ethernet cables will NOT work
STEP 2
In ShinePhone inverter settings, set battery type to 'Growatt ARK HV' (for XH-A1) or confirm correct protocol. Power cycle both battery (circuit breaker off for 30s) and inverter
Escalate if
Cable confirmed correct and battery type set correctly — swap cable. If still failing, check inverter firmware version compatibility with ARK battery generation
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