Wattsonic wattsonic (battery)

Installation

1. 1Connect the Wattsonic LAN dongle to your local network and confirm the inverter is reachable by IP. No RS485 wiring is needed for TCP access; the dongle exposes Modbus TCP on port 502.
2. 2In the ModbusCloud portal, add your ModbusCloud Gateway to the same LAN segment as the Wattsonic inverter, then create a new device and import the Wattsonic (battery) template.
3. 3Set the unit ID to 255 and enter the inverter's local IP address and port 502 in the device connection settings. Save and activate the configuration.
4. 4Spot-check the soc register in the live data view and compare the reading against the Wattsonic app or display. If the value is zero or an error, verify the unit ID and that the LAN dongle is online.

Things to watch for

01

All registers return exception code 2 (illegal data address). What is wrong?

Wattsonic inverters require the polling address to be the documented address plus one. If the template address is 43000, the device expects 43001 to be queried. This is a known quirk of the Wattsonic register table. Check that the template addresses in your portal match the OpenEMS offsets, which already account for this shift.

02

The gateway connects but battery SOC reads zero even though the battery is charged.

Confirm the LAN dongle is fully initialised and the inverter is not in standby or night mode, which can suppress some register responses. Also verify unit ID is set to 255. If using Wi-Fi instead of a wired LAN dongle, switch to a wired connection as the Wi-Fi interface is known to produce intermittent timeouts and read errors.

03

I wrote to the limitsoc register but nothing changed on the inverter.

Register 52503 accepts values from 100 to 900, representing 10 to 90 percent. Writing outside this range is silently ignored. Also note that Modbus writes to the Wattsonic are not immediately reflected in the Wattsonic cloud app; the change takes effect on the inverter itself but may not propagate back to the cloud interface.

04

Is it safe to write to the limitsoc register frequently from an automation?

Use caution. Register 52503 controls the on-grid battery discharge end SOC, which governs how deeply the battery can discharge. Writing incorrect values can prevent the battery from discharging at all or push it below manufacturer-recommended depth of discharge, potentially accelerating degradation. Always write values within the 100 to 900 range and test changes during commissioning before enabling automated writes.

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