Industrial Modbus to MQTT Converter Variant 23 Kit with ESP32 + LED
Industrial Modbus to MQTT Converter Kit with ESP32 — Make Legacy RTU Sensors Talk to Any MQTT Broker
Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.
Bring your industrial sensor data online with a custom-built Modbus-to-MQTT gateway. Whether you’re interfacing a decades-old energy meter, a PLC, or a temperature controller with RS485 output, this kit lets you publish every register value to a cloud MQTT broker — no proprietary gateway needed. You’ll assemble a DIN-rail-mounted converter that polls Modbus RTU slaves and streams real-time data to dashboards like Node-RED, Home Assistant, or AWS IoT.
What You'll Build
You will build a fully functional industrial protocol bridge that lives on a DIN rail inside any control panel. The device connects to an RS485 Modbus RTU network, reads holding and input registers using standard function codes, timestamps every sample with an RTC, and stores records on a microSD card. The ESP32 then publishes JSON payloads over WiFi to any MQTT broker, while the 0.96-inch OLED shows live register values and connection status. It’s a complete edge-to-cloud data pipeline for factory floors, energy audits, and remote monitoring stations.
What You'll Learn
- Implementing Modbus RTU master protocol using MAX485 and ESP32 — parsing function codes 03, 04, and 06
- Structuring and publishing data to MQTT topics with configurable QoS and retain flags
- Timing-sensitive RS485 half-duplex communication with appropriate DE/RE control and 120Ω termination
- Integrating an RTC and SD card for edge buffering and offline data logging with automatic replay after reconnection
Kit Contents
| Component | Quantity |
|---|---|
| ESP32 Dev Board | 1 |
| MAX485 RS485 | 1 |
| DS3231 RTC | 1 |
| MicroSD Module | 1 |
| 0.96in OLED | 1 |
| LM2596 Buck Converter | 1 |
| 120Ω Resistors | 5 |
| 10kΩ Resistors | 5 |
| 100nF Caps | 10 |
| PCB Prototype Board | 2 |
| DIN Rail Enclosure | 1 |
| 12V Adapter | 1 |
| Soldering Iron | 1 |
| Solder Wire | 1 |
Why Buy This Kit Instead of Sourcing Parts Separately
| Factor | Sourcing Separately | Compoden Kit |
|---|---|---|
| Compatibility checks | You verify every part | Pre-tested as a system |
| Build support | Forums and scattered tutorials | AI companion trained on this exact project |
| Time to first working build | Days of debugging | Hours, with step-by-step guidance |
| Shipping coordination | Multiple sellers, multiple delays | One shipment from Bengaluru in 3-5 days |
Who This Kit Is For
If you’re a B.Tech ECE/EEE student at VIT, NIT, BITS, or any Indian engineering college tackling an industrial IoT capstone, this kit gives you a working prototype in hours. It’s equally relevant for Smart India Hackathon teams building Industry 4.0 solutions and ATL lab instructors demonstrating Modbus-RTU-to-cloud pipelines. Professionals prototyping remote monitoring for factory automation will also appreciate the pre‑integrated logging and MQTT stack.
Built and Backed by Compoden
Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.
What if I get stuck during the build?
The AI companion is trained on this exact setup — it can diagnose register polling errors, MQTT connection failures, and wiring mistakes. If you need human help, our WhatsApp support also responds within 6 hours.
Can I connect multiple Modbus slaves on the same RS485 bus?
Yes, the MAX485 and the companion firmware support up to 32 devices on a single differential bus. You will learn how to address each slave and publish data to separate MQTT topics.
Does the kit support Modbus TCP as well?
This kit is built for Modbus RTU over RS485. However, the AI companion includes a sketch that turns the ESP32 into a simple Modbus TCP-to-RTU gateway, so you can also query the bus over Ethernet.
What happens to data if WiFi drops?
The DS3231 RTC and microSD module continuously log register values with timestamps. When the connection recovers, the firmware can replay buffered messages to the MQTT broker automatically.
MAX485 RS485 transceiver reads Modbus RTU registers from industrial sensor and republishes to MQTT via ESP32 WiFi.
What's in this kit
Choose your assembly option:
- Soldering Kit — 25W soldering iron, 60/40 solder wire, flux, and small perfboard for permanent assembly.
- Breadboard Combo — 800-point full-size breadboard with 65-piece jumper wire pack for solderless prototyping.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items