Why does the power register always read zero or garbage?

Register 31036 on H3 inverters must be read individually, not as part of a bulk block scan. Some firmware versions reject block reads that span certain address ranges. Configure the Gateway to poll this register in a single request, separate from other register groups.

The Gateway connects but the SoC register returns no value. What now?

Confirm the RS485 slave ID on the inverter matches the unit ID configured in the portal. The FoxESS H3 default slave address is 247 on many firmware versions. Also verify that only one RS485 master is active on the bus; a connected energy meter sharing the same bus can block responses.

Can I use the LAN port instead of RS485 for Modbus?

No. On current H3 firmware, Modbus TCP over the built-in LAN port is not supported because port 502 is closed. RS485 wiring to the ModbusCloud Gateway is the only confirmed working connection method for this inverter series.

Is it safe to write the limitsoc register remotely?

Use caution. Writing an incorrect minimum-SoC value via register 41009 can override the inverter's battery protection settings, potentially triggering deep-discharge faults or conflicting with warranty conditions. Test any write operation with a conservative value first, and confirm the result in the inverter's own display before automating writes.

Free Modbus template: FoxESS H3 Series Hybrid Inverter (battery)

The FoxESS H3 Series is a three-phase hybrid inverter available from 5 kW to 12 kW, designed for residential and light-commercial solar-plus-storage installations paired with high-voltage battery packs. This ModbusCloud template connects over Modbus RTU via the inverter's RS485 port and reads battery power (with sign-coded charge or discharge direction) and battery state of charge. It also exposes a writable minimum-SoC limit register, letting the portal enforce a discharge floor. Use this template to track battery behaviour and enforce operating limits without relying on the FoxESS cloud.

Name	Address	Function	Type	Unit	Access
power Battery power in watts; negative value means charging.	31036	FC03	int16	W	R
soc Battery state of charge, 0 to 100 percent.	31038	FC03	int16	%	R
limitsoc Minimum state-of-charge setpoint written to the inverter.	41009	FC16	uint16	%	W