---
title: "IRIV IO Controller IoT Gateway : Blynk"
url: "https://maker.wiznet.io/irina/projects/iriv-io-controller-iot-gateway--blynk/"
markdown_url: "https://maker.wiznet.io/irina/projects/iriv-io-controller-iot-gateway--blynk/md"
type: "UCC: User Created Content"
author: "Hussien Jawhar Sathik"
author_url: "https://my.cytron.io/tutorial/iriv-io-controller-iot-gateway-blynk"
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-blynk"
published: "2025-08-27"
language: "en"
tags: ["W5500", "CircuitPython"]
likes: 0
views: 5461
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---

# IRIV IO Controller IoT Gateway : Blynk

> Read RS-485 Modbus temp/humidity on IRIV IO Controller and send to Blynk (V0/V1) over Ethernet using WIZnet W5x00 in CircuitPython. Includes steps and code.

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

## Article

This tutorial shows how to use an **IRIV IO Controller** to read temperature/humidity from an **RS-485 (Modbus RTU)** sensor and upload the values to the **Blynk cloud** (virtual pins **V0/V1**) over **Ethernet** using a **WIZnet W5x00** driver in CircuitPython. Blynk provides an easy mobile/dashboard UI so you can monitor values in real time. The original Cytron guide demonstrates the full flow with example code and screenshots.

---

### 🔧 Project Overview

**Project Name:** IRIV IO Controller IoT Gateway : Blynk
**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:** Blynk IoT (Virtual Pins **V0** = Temperature, **V1** = Humidity)
**What You’ll See:** Terminal prints that match the live values on the Blynk dashboard.

> The tutorial uses Blynk virtual pins **V0/V1**, shows how to get a **Blynk Auth Token**, and explains where to place it in the code.

---

### ⚡ How the Project Works

#### 1) Hardware Setup

**IRIV IO ControllerRS-485 (Modbus RTU) temperature/humidity sensor** (e.g., slave address 1, registers 0/1)

**Ethernet connection** (DHCP recommended)

On IRIV, initialize the W5x00 via SPI using `adafruit_wiznet5k` (DHCP), then create an HTTP session.

#### 2) Protocols & Control

**Modbus RTU:** Read holding registers from the sensor (commonly **reg 0 → humidity**, **reg 1 → temperature**) and apply scaling as required.

**Blynk:** Use the **External HTTP API** (`.../external/api/update`) to update **V0/V1**. The code sends GET requests via `adafruit_requests`.

#### 3) Development Process

Obtain a **Blynk Auth Token** (from your Blynk device settings).

In code, set your **token** and **virtual pins (V0/V1)**.

Upload and run on IRIV → verify terminal readings and the Blynk app values update together.

---

## 💡 Key Features & Benefits

### Features

**IRIV IO Controller + W5x00 Ethernet:** Stable wired uplink for reliable cloud updates.

**Modbus RTU integration:** Periodically polls RS-485 registers for temperature/humidity.

**Blynk virtual pins:** Push data to **V0 (Temp) / V1 (RH)** and visualize instantly in the app.

**CircuitPython example:** Implemented with `adafruit_wiznet5k`, `adafruit_requests`, and `uModbus` in just dozens of lines.

### Applications

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

**Industrial Edge:** Bridge on-site RS-485 sensors to a cloud dashboard

**Smart Home/Office:** Robust, IP-based sensing backhaul

![](https://maker.wiznet.io/upload/ckeditor5/860796700%5F1756370114%2Epng)

---

### Code Highlights (Essentials)

The original example follows this flow (replace the token with **your** token):

Initialize **W5x00 (DHCP)** → build a socket pool/SSL context → create an **HTTP session**

Read **Modbus** registers (e.g., slave 1, address 1 → temperature; address 0 → humidity)

Call **Blynk API**:

```plaintext
.../external/api/update?token=YOUR_TOKEN&V0=<temperature>

.../external/api/update?token=YOUR_TOKEN&V1=<humidity>
```

> Note: Any token shown in screenshots is an example—use your own token from Blynk.
>
> ![](https://maker.wiznet.io/upload/ckeditor5/860796700%5F1756374237%2Epng)

---

### Troubleshooting Tips

**No updates on Blynk:** Double-check token spelling, virtual pin names (**V0/V1**), and request URL. Ensure `blynk.cloud` is reachable (no firewall/proxy blocks).

**Modbus read errors:** Verify slave address, register indices (0/1), baud rate, parity, stop bits, and any scaling factors from your sensor datasheet.

**DHCP issues:** Check cable/switch/router. If needed, test with a static IP on the W5x00 to rule out DHCP conflicts.

---

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