The gateway connects but all register reads return errors. Why?

The iHomeManager uses Sungrow's one-based register addressing convention. The protocol document lists register numbers starting at 1, which means the zero-based address polled over Modbus is always one less than the documented number. The register addresses in this template already apply that offset, so if you see errors, confirm you are targeting the correct unit ID (commonly 247) and port 502.

Grid power and energy values disappeared after the iHM was installed.

This is expected behavior. When a Sungrow iHomeManager is added, the inverter stops exposing grid metering data through its own Modbus registers. You must poll the iHM directly using this template. Do not query the inverter's grid registers in parallel; the iHM is now the authoritative meter source.

Only one Modbus client can read the iHM at a time. How do I share access?

The iHomeManager Modbus TCP interface allows only a single active connection per port. If another tool such as Home Assistant or iSolarCloud is already connected, the ModbusCloud Gateway will be refused. Close or disable other Modbus polling clients, or stagger poll schedules so connections do not overlap.

Per-phase voltage or power reads return zero on one or more phases.

Zero readings on individual phases are most often caused by single-phase or two-phase installations where unused phase registers return zero by design, or by a short polling timeout. Verify that the physical installation is three-phase. If it is, increase the read timeout in the portal gateway settings and re-poll. If only one phase is wired, zero on the unused channels is correct.

Free Modbus template: Sungrow iHomeManager (iHM) (grid)

The Sungrow iHomeManager (iHM) is a residential home energy management system with a built-in grid meter, replacing any separate metering device at the grid connection point. When the iHM is installed, grid import and export data is no longer available through the inverter's own Modbus interface, so the iHM must be queried directly. This template reads the iHM's grid registers over Modbus TCP: total active power, cumulative energy, and per-phase voltages and active power for phases A, B, and C. It gives installers and asset managers accurate, real-time grid data without any additional hardware.

Name	Address	Function	Type	Unit	Access
power Total active power at the grid connection point, signed integer.	8156	FC04	int32	W	R
energy Cumulative energy measured at the grid meter.	8175	FC04	uint32	Wh	R
voltages_a AC voltage on phase A at the grid meter.	8554	FC04	uint16	V	R
voltages_b AC voltage on phase B at the grid meter.	8555	FC04	uint16	V	R
voltages_c AC voltage on phase C at the grid meter.	8556	FC04	uint16	V	R
powers_a Active power on phase A at the grid meter.	8558	FC04	uint32	W	R
powers_b Active power on phase B at the grid meter.	8560	FC04	uint32	W	R
powers_c Active power on phase C at the grid meter.	8562	FC04	uint32	W	R