The gateway connects but all register reads time out. What now?

The SUN2000 Modbus TCP interface is sensitive to response timing. Set your Modbus timeout to at least 10 seconds and add a connection delay of 1 second before the first read. Short timeouts are the most common cause of consistent read failures, especially via the Smart Dongle over Wi-Fi.

Register 37113 returns zero or refuses to respond after a firmware update.

Firmware updates on the Smart Dongle or inverter can disable Modbus TCP and may also change the TCP port from 502 to 6607. Re-enable Modbus TCP under Dongle Parameter Settings in the SUN2000 app, then verify the active port and update your ModbusCloud Gateway configuration accordingly.

Phase current values on registers 37107, 37109, 37111 look 100 times too large. Why?

The Huawei Smart Power Sensor reports phase currents with a scaling gain of 100 (raw value in units of 0.01 A). If your portal or integration does not apply this scaling, readings will appear inflated by a factor of 100. Confirm the template scaling is set to divide by 100 before comparing against a clamp meter reading.

The gateway loses connection intermittently, especially during cloud sync.

The SUN2000 Smart Dongle can only handle one active Modbus TCP connection at a time. When the dongle is simultaneously uploading to FusionSolar, it may refuse or drop additional TCP connections. Use a longer connect delay and keep polling intervals at 30 seconds or more to reduce contention.

Free Modbus template: Huawei SUN2000 Hybrid Inverter (grid)

The Huawei SUN2000 is a hybrid solar inverter used in residential and commercial PV installations with battery storage. This template reads grid-side data from the inverter's internal Smart Power Sensor interface over Modbus TCP. It covers active grid power (signed, distinguishing feed-in from import), cumulative energy drawn from the grid, and per-phase currents for phases A, B, and C. Connecting this data to your ModbusCloud portal gives installers and building owners a continuous, timestamped view of grid exchange, enabling accurate energy balance calculations and anomaly detection.

Name	Address	Function	Type	Unit	Access
power Active grid power in watts, positive feed-in, negative import.	37113	FC03	int32	W	R
energy Cumulative energy supplied from the grid to the system.	37121	FC03	uint32	Wh	R
currents_a Grid phase A current from the Smart Power Sensor.	37107	FC03	int32	A	R
currents_b Grid phase B current from the Smart Power Sensor.	37109	FC03	int32	A	R
currents_c Grid phase C current from the Smart Power Sensor.	37111	FC03	int32	A	R