---
title: "IRIV IO Controller IoT Gateway : MQTT"
url: "https://maker.wiznet.io/irina/projects/iriv-io-controller-iot-gateway--mqtt/"
markdown_url: "https://maker.wiznet.io/irina/projects/iriv-io-controller-iot-gateway--mqtt/md"
type: "UCC: User Created Content"
author: "Hussien Jawhar Sathik"
author_url: "https://my.cytron.io/tutorial/iriv-io-controller-iot-gateway-mqtt"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "Hussien Jawhar Sathik"
original_url: "https://my.cytron.io/tutorial/iriv-io-controller-iot-gateway-mqtt"
published: "2025-08-27"
language: "en"
likes: 0
views: 2324
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# IRIV IO Controller IoT Gateway : MQTT

> Read RS-485 Modbus temperature/humidity on IRIV IO Controller and publish to Adafruit IO via MQTT over Ethernet using WIZnet W5x00 in CircuitPython.

Original author: Hussien Jawhar Sathik (source: https://my.cytron.io/tutorial/iriv-io-controller-iot-gateway-mqtt)

## Article

This tutorial shows how to use an **IRIV IO Controller** to read temperature and humidity from an **RS-485 (Modbus RTU)** sensor and publish both values to **Adafruit IO over MQTT** via **Ethernet** using a **WIZnet W5x00** driver in CircuitPython. You’ll create an Adafruit IO account, collect your **AIO Key**, create two **feeds** (Temperature/Humidity), place credentials in `settings.toml`, then publish with `adafruit_minimqtt`—exactly as in the original Cytron guide.

---

## 🔧 Project Overview

**Project Name:** IRIV IO Controller IoT Gateway : MQTT
**Author (Tutorial):** Hussien Jawhar Sathik (Cytron)
**Platform:** IRIV IO Controller (CircuitPython)
**Networking:** WIZnet W5x00 (CircuitPython `adafruit_wiznet5k`)
**Field Bus:** RS-485 (Modbus RTU)
**Cloud/App:** Adafruit IO via **MQTT** (two feeds: **Temperature**, **Humidity**)
**What You’ll See:** Console prints for temp/humidity and MQTT publish logs; matching live values on Adafruit IO dashboards.

> The tutorial uses **Adafruit IO** as the MQTT broker, obtaining the **AIO Key**, creating feeds, and wiring credentials through `settings.toml`.

---

## ⚡ How the Project Works

### 1) Hardware Setup

**IRIV IO ControllerRS-485 (Modbus RTU) temperature/humidity sensor** (e.g., slave address 1)

**Ethernet** connection (DHCP recommended)

Initialize W5x00 via SPI (`adafruit_wiznet5k`), create socket/SSL context, then build an MQTT client session.

### 2) Protocols & Control

**Modbus RTU:** Read holding registers—example maps **reg 1 → temperature** and **reg 0 → humidity**, with a `/10` scaling.

**MQTT (Adafruit IO):** Use `adafruit_minimqtt` to connect to `io.adafruit.com` with **username + AIO Key**, then `publish()` to `username/feeds/Temperature` and `username/feeds/Humidity`.

### 3) Development Process

Create an **Adafruit IO** account; copy the **AIO Key** and put it in `**settings.toml**` (e.g., `aio_username`, `aio_key`).

Create two **feeds**: **Temperature** and **Humidity**; reference them in code.

Run on IRIV → verify console output and that both feeds update on Adafruit IO.

---

## 💡 Key Features & Benefits

### Features

**IRIV + W5x00 Ethernet:** Stable wired uplink for MQTT telemetry.

**Modbus RTU integration:** Periodic RS-485 polling for T/RH with simple scaling.

**MQTT to Adafruit IO:** Straightforward publish to `Temperature`/`Humidity` feeds.

**CircuitPython stack:** `adafruit_wiznet5k`, `adafruit_minimqtt`, `adafruit_requests`, `uModbus`—compact, readable code.

### Applications

**Building/Facility:** Environmental monitoring (temperature/humidity)

**Industrial Edge:** RS-485 sensors bridged to cloud dashboards

**Smart Home/Office:** Robust IP backhaul for sensor data

---

### Code Highlights (Essentials)

Below is the distilled flow from the tutorial—replace with **your** Adafruit IO credentials and feeds.

```python
import os, time, board, busio
import adafruit_connection_manager, adafruit_requests
from digitalio import DigitalInOut
from adafruit_wiznet5k.adafruit_wiznet5k import WIZNET5K
from umodbus.serial import Serial as ModbusRTUMaster
import adafruit_minimqtt.adafruit_minimqtt as MQTT

# AIO credentials (from settings.toml)
AIO_USER = os.getenv("aio_username")
AIO_KEY  = os.getenv("aio_key")

# Ethernet (DHCP)
cs  = DigitalInOut(board.W5500_CS)
spi = busio.SPI(board.SCK, MOSI=board.MOSI, MISO=board.MISO)
eth = WIZNET5K(spi, cs)

# Socket pool for MQTT
pool = adafruit_connection_manager.get_radio_socketpool(eth)

# MQTT client (non-SSL shown for brevity)
mqtt = MQTT.MQTT(broker="io.adafruit.com",
                 username=AIO_USER, password=AIO_KEY,
                 is_ssl=False, socket_pool=pool, ssl_context=None)

# Modbus master
host = ModbusRTUMaster(tx_pin=board.TX, rx_pin=board.RX)

mqtt.connect()
while True:
    # Example: reg1=temp(°C*10), reg0=humidity(%*10)
    temperature = host.read_holding_registers(1, 1, 1)[0] / 10.0
    humidity    = host.read_holding_registers(1, 0, 1)[0] / 10.0
    mqtt.loop()
    mqtt.publish(f"{AIO_USER}/feeds/Temperature", temperature)
    mqtt.publish(f"{AIO_USER}/feeds/Humidity",    humidity)
    time.sleep(5)
```

The original sample shows the same broker/feeds, credential handling via `settings.toml`, and `adafruit_minimqtt` usage.

![](https://maker.wiznet.io/upload/ckeditor5/860796700%5F1756374371%2Epng)

---

### Troubleshooting Tips

**No feed updates?** Check **AIO username/key**, feed names, and network reachability to `io.adafruit.com`.

**Bad readings?** Confirm Modbus slave address, register indices (1 and 0), baud/parity/stop bits, and scaling factor.

**DHCP issues:** Try a static IP on the W5x00 to rule out local network conflicts.

---

Source: https://maker.wiznet.io/irina/projects/iriv-io-controller-iot-gateway--mqtt/