A-Tronix wattsonic (battery)
The A-Tronix wattsonic is a hybrid solar inverter with integrated battery storage, distributed under the A-Tronix brand and based on the Wattsonic platform. It is deployed in residential and small commercial PV installations for self-consumption optimisation and backup power. This Modbus TCP template reads battery charge and discharge power, state of charge, and exposes a writable minimum-SOC setpoint that controls how far the battery discharges on-grid. Together these three registers give your ModbusCloud portal full visibility of battery behaviour and remote floor-setting of the discharge limit.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 3, read and write
- Brand
- A-Tronix
- Compatible models
- wattsonic
- Last updated
Registers (3)
2 read, 1 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| soc | % | Read | |||
| limitsoc | % | Write |
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Use cases
- Monitor live battery charge and discharge power to verify storage behaviour during peak solar production hours.
- Track battery state of charge over time to detect capacity degradation across seasons.
- Alert on state of charge falling below a configured threshold to prevent unexpected load interruptions.
- Verify that the minimum SOC setpoint written via the portal takes effect before an EV charging session begins.
- Compare daily battery cycling patterns across multiple A-Tronix wattsonic sites in the multi-site overview.
Installation
Enable Modbus TCP on the wattsonic inverter by navigating to the communication or network settings on the inverter display, confirm the LAN module is connected, note the assigned IP address, and set Modbus unit ID to 247 or 255 as configured on your unit.
Connect the inverter LAN port to the same local network as the ModbusCloud Gateway, ensuring the Gateway can reach the inverter IP on TCP port 502.
In your ModbusCloud portal, add the Gateway, import the A-Tronix wattsonic (battery) template, and assign the correct unit ID and host IP matching the inverter network settings.
Spot-check the connection by reading the soc register (address 43000) in the portal live data view and confirming the percentage matches the value shown on the inverter display or the Wattsonic monitoring app.
Things to watch for
Why does the SOC register always return an error or zero?
Some Wattsonic firmware versions require the register address to be offset by one when read over Modbus TCP. Confirm your unit ID is 247 or 255 and that TCP port 502 is reachable. If the value is still wrong, check whether the LAN dongle is the active communication path and not an RS485 converter.
The gateway connects but battery power reads as garbage. What now?
Register 40258 returns a signed int32 value where negative means discharge. If your portal shows an implausibly large number, check that the data type is decoded as int32 and not uint32. A uint32 decode of a negative int32 will produce a very large unsigned value.
No data appears at all after importing the template. What should I check?
Confirm the inverter LAN module is active and the inverter IP is reachable from the ModbusCloud Gateway on port 502. The Wattsonic inverter defaults to unit ID 255 on TCP; if your unit was reconfigured to 247, update the unit ID in the portal template assignment accordingly.
Is it safe to write values to the limitsoc setpoint register remotely?
Use caution when writing to register 52503. This setpoint controls the minimum battery SOC floor on-grid; writing a value that is too high could prevent the battery from discharging at all, affecting backup power availability. Always restore to your intended default value after any automated session ends, and stay within the documented range supported by the inverter.
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