The gateway connects but the power register always reads zero. Why?

Some FoxESS firmware versions respond with unit ID 0 instead of the requested unit ID 1, which causes clients to discard the response. Try setting the Modbus unit ID in the portal to 0 instead of 1. If a second Modbus client such as Home Assistant or openHAB is polling the device at the same time, disconnect it during testing, as the device only handles one TCP connection at a time.

Phase voltage values look ten times too high. What is wrong?

The FoxESS Modbus protocol applies a gain of 10 to the voltage registers at addresses 39123 to 39125. If your integration or display layer does not apply this scaling, readings will appear inflated by a factor of ten. Confirm that the template's scaling factor is set to divide by 10 before displaying or alerting on voltage values.

Current registers return implausible values despite correct addressing. What now?

The phase current registers are 32-bit signed integers with a documented gain of 1000, meaning raw values represent milliamps. Some FoxESS models shift the useful data to the second word of the 32-bit pair, making the first word read as zero. If values are implausible, verify that your Modbus client reads both words and assembles them as a big-endian int32.

The energy register shows a lower number than the FoxESS app. Is the data wrong?

The energy register at address 39625 is a raw unsigned 32-bit counter internal to the inverter register map. It may represent a different energy accumulation boundary, such as a subset of grid energy, compared to what the FoxESS cloud app derives from additional registers. Use the value for trend monitoring and relative comparisons rather than as an absolute billing figure.

Free Modbus template: FoxESS Avocado (grid)

The FoxESS Avocado is a compact all-in-one hybrid battery storage and inverter system sold under several names, including the MQ2200 and ONE. This template targets the grid metering registers exposed over Modbus TCP on port 502, covering combined grid active power, cumulative energy, and per-phase voltages and currents for all three phases. With the ModbusCloud Gateway connected to the same LAN, your portal shows live import and export power, phase-level voltage balance, and a running energy total, giving installers the data needed to verify grid interaction at a glance.

Name	Address	Function	Type	Unit	Access
power Grid active power; positive = import, negative = export.	39168	FC03	int32	W	R
energy Cumulative grid energy counter, unsigned 32-bit integer.	39625	FC03	uint32	Wh	R
voltages_a Grid phase A (R-phase) voltage, signed 16-bit.	39123	FC03	int16	V	R
voltages_b Grid phase B (S-phase) voltage, signed 16-bit.	39124	FC03	int16	V	R
voltages_c Grid phase C (T-phase) voltage, signed 16-bit.	39125	FC03	int16	V	R
currents_a Grid phase A (R-phase) current, signed 32-bit.	39126	FC03	int32	A	R
currents_b Grid phase B (S-phase) current, signed 32-bit.	39128	FC03	int32	A	R
currents_c Grid phase C (T-phase) current, signed 32-bit.	39130	FC03	int32	A	R

FoxESS Avocado (grid)

Overview

Use cases

Installation

Things to watch for

Registers (8)

Working with Modbus in your projects?

Free: RS485 and Modbus RTU installation checklist (PDF)

More FoxESS templates

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FoxESS H1 Series Hybrid Inverter (battery)

FoxESS H3 Series Hybrid Inverter (grid)

FoxESS H3-Pro/Smart Series Hybrid Inverter (pv)

FoxESS Avocado (pv)

FoxESS Avocado (battery)

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