Sunway wattsonic (pv)

Installation

1. 1Connect the wattsonic inverter's LAN dongle to the same local network as the ModbusCloud Gateway, and confirm the inverter has a stable IP address on port 502.
2. 2In the ModbusCloud portal, add a new device, import the Sunway wattsonic (pv) template, and set the unit ID to 255 as used by the inverter's built-in Modbus TCP server.
3. 3Assign the gateway to the device entry in the portal, enter the inverter's local IP address and port 502 under the communication or Modbus section, then save.
4. 4Trigger a manual poll in the portal and verify that register 11028 returns a non-zero watt value during daylight hours to confirm connectivity.

Things to watch for

01

Why does register 11028 always return zero at night?

This is expected behaviour. The wattsonic reports zero PV generation when no solar input is present. Verify the reading is non-zero during daylight. If it remains zero in full sun, check that the unit ID is set to 255 and the correct inverter IP is configured in the portal.

02

The gateway connects but no values appear in the portal. What now?

Confirm the inverter's LAN dongle is active and the inverter is reachable on port 502 from the gateway's network segment. Some firmware versions require the Modbus TCP server to be explicitly enabled under the inverter's communication or network settings. Check that the local firewall is not blocking port 502.

03

Register addresses from the official documentation do not match what works. Why?

The wattsonic register table uses zero-based addresses internally, but the Modbus TCP server applies a +1 offset. The address 11028 in this template already accounts for this offset. Do not subtract 1 when configuring the gateway: use 11028 as-is.

04

The PV power value looks correct sometimes but shows errors intermittently. What causes this?

The wattsonic LAN dongle can produce read timeouts under continuous polling. Community users report that adding a 100 ms inter-request delay reduces errors significantly. Also confirm only one Modbus TCP client is polling at a time, as the dongle supports a limited number of concurrent connections.

Registers (1)

1 read / 0 write

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