sitsolar-dongle

Read-only Modbus client for the SiNeng / FuturaPulse WiFi dongle used by Sit Solar inverters.

A read-only Modbus client for the SiNeng / FuturaPulse WiFi dongle that ships with Sit Solar inverters — the "Si-Dongle-L" that listens on TCP port 7078.

It speaks the same secure Modbus frame as the official Android app, so you can pull the inverter's telemetry straight off your LAN instead of routing it through the vendor cloud.

Read-only by design

Nothing in this package ever writes to the inverter. Only Modbus function codes 0x04 (read input registers) and 0x03 (read holding registers) are implemented. The entire writable holding-register block 40001–49999 is deliberately absent from the register map.

Unofficial project

This project is not affiliated with, endorsed by, or supported by SiNeng, FuturaPulse, or Sit Solar. The protocol was reverse-engineered from the vendor's Android app and its published Modbus protocol document. Use it at your own risk, on your own equipment.

One command to telemetry

Keys derived from the serial

Authenticated frames

sitsolar-dongle 192.168.1.50 --sn <SERIAL> connects, authenticates, and prints every decoded value. Add --json for machine-readable output.

Both the AES and HMAC keys are derived from the dongle's printed serial number. There is nothing else to configure.

Every frame is AES-128-CBC encrypted and HMAC-SHA256 signed. The MAC is checked before decryption, so a wrong key fails cleanly instead of producing garbage.

183 documented values

Home-automation friendly

Also a library

A complete register map transcribed from the FuturaPulse hybrid inverter Modbus protocol, with enum labels, bit fields, and per-register scale factors.

--interval polls forever and --json emits one object per sample, ready to feed Home Assistant, MQTT, or InfluxDB.

from sitsolar_dongle import DongleClient gives you the same session as a plain Python API.

Quick start

git clone https://github.com/ch3p4ll3/sitsolar-dongle.git
cd sitsolar-dongle
uv venv && uv sync

sitsolar-dongle 192.168.1.50 --sn <DONGLE_SERIAL>

Head to Getting Started for the full walkthrough, including how to find your dongle and locate its serial number.

Treat the serial number like a password

Both session keys are derived from the dongle serial alone, so anyone on your network who knows that serial can talk to the dongle. Do not commit it, paste it into issues, or share logs and packet captures that contain it.

What's in these docs

Section	What you'll find
Getting Started	Requirements, installation, and your first poll.
CLI Reference	Every command-line option, exit code, and output mode.
Python API	Using `DongleClient` and the lower-level building blocks.
Protocol	The wire format, handshake, and secure envelope.
Register Map	All 183 values with types, scales, and known quirks.
Caveats & Troubleshooting	Firmware differences, connection limits, and common failures.
Development	Project layout, architecture, and running the test suite.

Tested with


Dongle	SiNeng / FuturaPulse "Si-Dongle-L"
Inverter	Futura Sun 3K-HS (single-phase high-voltage hybrid, device type `33`)
Firmware	DSP1 `0000090021`, DSP2 `0000060010`, ARM `001002032`

Other models and firmware versions may expose different register blocks — see Caveats. Reports are welcome; please redact your serial number first.