The gateway connects but all register values read as zero or error.

The StoraXe Master Controller Modbus TCP interface is only active when the system is in an operational state (not off or standby). Confirm the system state on the local controller display. Also verify the unit ID in the portal matches the slave address configured in the StoraXe communication settings, as a mismatch returns no valid data.

The energy register at address 114 returns an implausibly large value. Why?

The energy register is a 32-bit unsigned cumulative counter. If your Modbus client reads only the lower 16 bits, the value will be incorrect. Ensure your polling configuration reads both registers as a single uint32 block using function code 4. The StoraXe uses big-endian (high byte first) byte order, so the high word must be read at address 114 and the low word at 115.

The power register shows negative values when I expect positive discharge readings.

This is correct behavior per the Ads-tec StoraXe interface specification: a negative power value indicates the system is charging (power flowing from grid into the battery), while a positive value indicates discharge. Check your energy management system logic or dashboard formula to ensure the sign convention is applied correctly before triggering alerts.

Phase current readings on currents_a, currents_b, or currents_c look inconsistent across phases.

Verify the three-phase wiring at the StoraXe AC connection point. Current imbalance can result from an unequal load distribution on the building LV network, but persistent imbalance exceeding expected tolerances may indicate a wiring fault. Also confirm the register block (addresses 9 to 11) is polled in a single contiguous read request to avoid stale interleaved values.

Free Modbus template: Ads-tec StoraXe (battery)

Name: Ads-tec StoraXe (battery)
Brand: Ads-tec
SKU: f726d0f8-a6e9-4981-bdc1-b820cd1032c8

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Free Modbus template: Ads-tec StoraXe (battery) | ModbusCloud

Registers (9)

9 read / 0 write

Name	Address	Function	Type	Unit	Access
power Instantaneous AC power; negative indicates charging, positive discharging.	1	FC04	int16	W	R
energy Cumulative energy throughput counter, 32-bit unsigned value.	114	FC04	uint32	Wh	R
voltages_a AC voltage on phase A at the inverter AC terminals.	6	FC04	int16	V	R
voltages_b AC voltage on phase B at the inverter AC terminals.	7	FC04	int16	V	R
voltages_c AC voltage on phase C at the inverter AC terminals.	8	FC04	int16	V	R
currents_a AC current on phase A; signed, negative when charging.	9	FC04	int16	A	R
currents_b AC current on phase B; signed, negative when charging.	10	FC04	int16	A	R
currents_c AC current on phase C; signed, negative when charging.	11	FC04	int16	A	R
soc Battery state of charge reported by the system BMS.	125	FC04	int16	%	R