--- title: "MonSet-Dev" url: "https://maker.wiznet.io/lawrence/projects/monset-dev/" markdown_url: "https://maker.wiznet.io/lawrence/projects/monset-dev/md" type: "UCC: User Created Content" author: "west3005" author_url: "https://github.com/west3005/MonSet-Dev" editor: "WIZnet" editor_url: "https://maker.wiznet.io/" original_author: "west3005" original_url: "https://github.com/west3005/MonSet-Dev" published: "2026-05-24" language: "en" tags: ["Modbus"] likes: 0 views: 356 comments: 0 source: "WIZnet Makers (https://maker.wiznet.io/)" --- # MonSet-Dev > MonSet is an industrial-grade IoT monitoring device built around the STM32F407VET6 microcontroller. It reads sensor data over Modbus RTU (RS-485) Original author: west3005 (source: https://github.com/west3005/MonSet-Dev) ## Article ## MonSet — Industrial IoT Monitoring Device with W5500 Ethernet, NB-IoT, and Multi-Channel Failover on STM32F407 **Tags:** W5500 · STM32 · Modbus RTU · MQTT · ThingsBoard · Industrial IoT · NB-IoT · TLS ### Overview MonSet is an industrial-grade IoT monitoring device built around the **STM32F407VET6** microcontroller. It reads sensor data over **Modbus RTU (RS-485)**, logs it to a MicroSD card, and transmits telemetry to a **ThingsBoard** cloud platform via **WIZnet W5500 Ethernet** or **SIM7020C NB-IoT** — with automatic failover across multiple communication channels. The project targets remote industrial sites such as water level monitoring stations, pumping facilities, and environmental measurement points where reliable, multi-channel connectivity and offline-safe data buffering are critical requirements. ### Hardware Platform | Component | Description | | --- | --- | | **MCU** | STM32F407VET6 — 168 MHz, 512 KB Flash, 192 KB RAM | | **Ethernet** | WIZnet **W5500** via SPI1 | | **NB-IoT / GSM** | SIM7020C → SIM7020E (NB-IoT Cat NB1) | | **WiFi** | ESP8266 (USART6) | | **Satellite** | Iridium SBD NR9602G (UART5) | | **RTC** | DS3231 (I2C1) | | **Sensors** | Modbus RTU via USART3 + UART4 (RS-485), configurable per-port | | **Storage** | MicroSD — FAT32 via SDIO 1-bit | ### How WIZnet W5500 is Used The W5500 is the **primary and highest-priority communication channel** in MonSet. It is connected over SPI1 (PA5/PA6/PA7) with a dedicated chip select on PA8, reset on PC3, and an interrupt line on PC4. The firmware uses WIZnet's **ioLibrary** (hardware TCP/IP offload stack) together with **mbedTLS 1.2** to open both **MQTT over TCP** and **HTTPS** sessions — protocol selection is runtime-configurable via `config.json` on the SD card. #### W5500 Socket Functions in MonSet **1. MQTT Telemetry (TCP)** The device publishes sensor readings to ThingsBoard MQTT broker at configurable intervals. The W5500 handles the TCP connection so the STM32 is free of software TCP/IP stack overhead. **2. HTTPS Telemetry (TLS over TCP)** For environments that require encrypted transport, MonSet uses mbedTLS on top of the W5500 TCP socket. The STM32's hardware RNG provides entropy for TLS handshakes. **3. Modbus TCP Master** The W5500 also opens TCP client sockets to poll Modbus TCP slave devices on the local LAN — without any change to firmware (register map is configured in JSON on SD). **4. Modbus TCP Slave** MonSet can itself act as a Modbus TCP server, exposing its sensor readings to SCADA systems (GE iFIX, WinCC, InTouch) on the local network. **5. Web Interface** A built-in HTTP server accessible through the W5500's static IP serves a full runtime web UI for configuration, live sensor values, and log download — no cloud dependency required. **6. NTP Time Sync** The device synchronizes its clock via NTP over the W5500 on startup and can fall back to the DS3231 hardware RTC. ### Multi-Channel Failover Architecture One of MonSet's key design strengths is its **priority-based channel switching**: ```plaintext Ethernet W5500 → GSM NB-IoT → WiFi ESP8266 → Iridium SBD (1st) (2nd) (3rd) (4th) ``` Each channel has its own WatchDog timer. When the active channel fails, the device automatically switches to the next available one and returns to the higher-priority channel once it recovers. During any outage, undelivered readings are saved to `Backup.json` on the SD card as JSONL and re-transmitted after the connection is restored — ensuring zero data loss. ![](https://maker.wiznet.io/upload/ckeditor5/343301796%5F1779649815%2Epng) ### Sensor Data Collection Sensors are read over two independent RS-485 Modbus RTU ports (USART3 and UART4). The register map — including device address, Modbus function code, data type (`int16` / `uint32` / `float`), scaling factor, and engineering unit — is defined in a JSON file on the SD card. New sensors can be added **without reflashing firmware**. Supported measurement pipeline: - Read raw Modbus registers - Apply zero-offset and scale coefficients - Average over N samples - Log to date-rotated `.txt` files on SD - Transmit to ThingsBoard / Home Assistant (Mosquitto) / Node-RED / Yandex IoT Core / HTTP Webhook ### Web Interface Features The built-in web server (accessible via W5500, ESP8266, or GSM static IP) provides: - **Live sensor readings** — no ThingsBoard needed - **Full configuration editor** — APN, MQTT broker, polling intervals, channel priorities, Modbus register map - **Runtime log viewer** — separate tab for log streaming - **Log download** — `.txt` log files direct to browser - **CSV export** — `Backup.json` → CSV for Excel / Google Sheets - **Battery level indicator** — read via STM32 ADC, shown in UI and sent to server - **Setup wizard (Captive Portal via ESP8266)** — simple and advanced modes for first-time configuration ### Application Fields MonSet is designed for and directly applicable to: - **Water infrastructure** — river/reservoir level monitoring, pumping station telemetry - **Environmental monitoring** — remote outdoor sensor stations - **Industrial automation** — Modbus RTU → cloud gateway for legacy PLCs and field instruments - **Smart building & facility management** — energy, temperature, humidity logging with SCADA integration - **Oil & gas / utilities** — remote RTU replacement with multi-channel backup connectivity --- ### Why W5500 for Industrial IoT? In industrial environments, **wired Ethernet is the most reliable communication medium**. The W5500's hardwired TCP/IP offload engine means the STM32 does not need to run a software network stack, freeing MCU cycles for Modbus polling, SD logging, and TLS processing simultaneously. The W5500 also enables MonSet to operate as both a **cloud-connected MQTT client** and a **local Modbus TCP server** on the same hardware — a dual-role that would be difficult to achieve with a software TCP/IP stack on a resource-constrained MCU. --- Source: https://maker.wiznet.io/lawrence/projects/monset-dev/