Send Modbus Data to ThingsBoard with Quectel EC25

Many industrial devices expose data through Modbus RTU over RS-485. The NORVI-GSM, powered by an ESP32 SoC and Quectel EC25 cellular modem, makes it simple to read these registers and push them securely to ThingsBoard using MQTT.

With this setup, you can:

Monitor sensors or meters in remote locations over cellular.

• Monitor sensors or meters in remote locations over cellular.
• Send real-time telemetry without relying on Wi-Fi.
• Build dashboards and alerts in ThingsBoard.

👉 A full working guide with code and diagrams is available here:NORVI Docs — Modbus Data to ThingsBoard with EC25

Steps

Step 1: Create Device in ThingsBoard

Log in to your ThingsBoard instance.

• Log in to your ThingsBoard instance.

Create a new device.

• Create a new device.

Copy the Access Token – this will be used in your code.

• Copy the Access Token – this will be used in your code.

Step 2: Wire the Hardware

Connect your Modbus slave device to the RS-485 A/B lines on the NORVI-GSM.

• Connect your Modbus slave device to the RS-485 A/B lines on the NORVI-GSM.
• Ensure proper polarity – if readings are zero, swap A/B lines.
• Ensure proper polarity – if readings are zero, swap A/B lines.
• Insert a SIM card with an active data plan into the EC25 slot.

Step 3: Prepare Arduino IDE

Install the ESP32 board package in Arduino IDE.

• Install the ESP32 board package in Arduino IDE.
• Install the ModbusMaster library from Library Manager.
• Open the example sketch provided in the NORVI Docs.

Step 4: Configure the Code

Replace YOUR_APN with your SIM’s APN.

• Replace YOUR_APN with your SIM’s APN.
• Insert the ThingsBoard Access Token.
• Insert the ThingsBoard Access Token.
• Set the correct Modbus slave ID and register addresses.

Step 5: Upload and Monitor

• Upload the sketch to the NORVI-GSM via USB.
• Open the serial monitor – check EC25 AT responses for +QMTOPEN and +QMTCONN.
• If successful, telemetry will be published to ThingsBoard.

Step 6: Visualize in ThingsBoard

Go to your device’s Latest Telemetry tab to confirm data.

• Go to your device’s Latest Telemetry tab to confirm data.
• Create a dashboard with widgets (gauges, charts, time-series plots).
• Bind widgets to telemetry keys like ANIN1, ANIN2.

Step 7: Troubleshooting

• All values zero? → Swap RS-485 A/B lines.
• No MQTT connection? → Check APN, token, and confirm PDP activation (AT+QIACT?).
• Random disconnects? → Enable MQTT KeepAlive and retry logic.

Attachments

Full Documentation with Code & Diagrams

• Example Arduino Sketch (in the linked docs)
• ThingsBoard Dashboard screenshots (see docs)
• Hardware wiring images (to be added in Hackster project gallery)