A 50-Year-Old HVAC Engineer Built an Android SCADA in Flutter

⚡ The gist in 5 seconds - A 50-year-old HVAC (heating) engineer single-handedly developed a universal Android SCADA engine in Flutter/Dart for control cabinets. - The app connects to PR200 controllers and any Modbus devices in three ways: USB-OTG, Wi-Fi, and the OwenCloud cloud. - Universality is achieved via JSON configuration: no app rebuild is needed for a new site — just swap the file. ### 🔍 What was found An author under the nickname liminal_space published a detailed case study on Habr on September 29. He is 50 years old and works as a heating systems engineer at a company that manufactures block heating substations. His daily tasks include designing ATM (automation and instrumentation) sections in AutoCAD and programming Owen PR200 relays paired with EKF panels. Without any formal programming education, he combined his instrumentation and control (I&C) experience with the help of neural networks and created a mobile app. The architecture is built around a dynamic JSON parser. At startup, the app reads a configuration file describing process systems, parameters, Modbus register addresses, data types, and alarm thresholds. Based on this, Flutter generates screens with sensors, relays, pumps, and valves. Three transport loops are implemented: field-level — Modbus RTU via USB-OTG, local — Modbus TCP over Wi-Fi, and global — HTTP REST API to OwenCloud. There are also trend screens, historical data, PDF report generation, and CSV export. ### 💡 Why it matters This case clearly shows that deep engineering experience in instrumentation and control can become the foundation for a full-fledged software product. The author didn't just automate routine work — he moved away from assembly-line development for each individual site, creating a tool that is configured by simply replacing a JSON file. For industry, this means reduced commissioning time: configuring a cabinet from a smartphone via Wi-Fi or USB eliminates the need to constantly stare at the controller's two-line display. And using the Owen cloud allows remote monitoring of an unlimited number of devices, even on the free tier. ### 🧩 Context The idea was born out of professional burnout: the author got tired of writing the same logic blocks and drawing typical screens over and over. The inconvenience of configuring via the PR200's two-line display and the need to simultaneously watch the indicator lights on the cabinet door and the relay positions pushed him toward the idea of a mobile app. The result was the "JSON Constructor" project: a client downloads the app via a QR code, then receives a QR code with their configuration file — and a mini-SCADA for a specific heating substation unfolds on the smartphone screen. The app supports saving multiple configurations and switching between them with a single tap.

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