Huawei SUN2000 Modbus TCP Overview

Huawei SUN2000 inverters (3-40 kW) expose Modbus TCP on port 6607 (NOT port 502). Unit ID is 0. These two non-standard values — port 6607 and unit ID 0 — are the most frequent causes of integration failures when engineers assume standard Modbus TCP defaults.

Key Holding Registers

All SUN2000 registers are holding registers read with function code 3. Key registers: 32064-32065 (active power, int32, 1W, two consecutive registers form a 32-bit value), 32078-32079 (daily energy yield, uint32, 0.01 kWh), 32087 (battery SOC, uint16, 0.1%), 32114-32115 (battery charge/discharge power, int32, 1W, positive=charge, negative=discharge).

Smart Dongle Requirement

The Huawei Smart Dongle (model SDongleA-05) is mandatory for Modbus TCP access. Without the dongle, only RS485 Modbus RTU is available on the inverter COM port. The dongle connects to the home LAN via WiFi or Ethernet and creates the Modbus TCP server on port 6607.

LUNA2000 Battery Integration

Huawei LUNA2000 battery connects to SUN2000 via internal CAN bus. Battery SOC and power registers (32087, 32114) are available on the same SUN2000 Modbus map — no separate connection to the battery is needed.

KNX Integration via LOYTEC LROC-100

The LOYTEC LROC-100 Modbus master is well-suited for SUN2000 integration. Configure two read tasks: task 1 polls register 32064 (power) every 10 seconds, task 2 polls registers 32087 and 32078 (SOC and energy) every 60 seconds. The LROC-100 has built-in KNX datapoint mapping, so no intermediate BACnet-to-KNX gateway is needed.

Forced Charge/Discharge via KNX

Huawei SUN2000 supports forced charge/discharge via Modbus write to register 47500: value 5 = forced charge, value 6 = forced discharge, value 0 = auto. KNX logic writes to this register via MDT Modbus gateway when grid tariff is low — use a KNX time switch object to trigger at off-peak tariff hours and write value 5, then write value 0 when the off-peak period ends.

Huawei SmartLogger for Commercial Installations

Larger commercial installations with multiple inverters use Huawei SmartLogger3000, which aggregates all inverter data and exposes a single Modbus TCP endpoint on port 502 (standard port). This simplifies KNX integration for multi-inverter sites. The register map is identical to single-inverter SUN2000, but addresses shift by inverter index (inverter 1 starts at 32064, inverter 2 at 32064+1000).

SolarEdge vs Huawei Port Comparison

Both SolarEdge and Huawei use Modbus TCP but with different non-standard port numbers and different register maps. The critical difference: SolarEdge uses port 1502, Huawei uses port 6607. Never mix these values when configuring gateways in a project that includes both inverter brands.