---
title: "Marstek Modbus Companion"
url: "https://maker.wiznet.io/jaden/projects/marstek-modbus-companion/"
markdown_url: "https://maker.wiznet.io/jaden/projects/marstek-modbus-companion/md"
type: "UCC: User Created Content"
author: "Nerdiy"
author_url: "https://github.com/Nerdiyde/Nerdiy_Products/tree/main/products/marstek_modbus_companion"
editor: "WIZnet"
editor_url: "https://maker.wiznet.io/"
original_author: "Nerdiy"
original_url: "https://github.com/Nerdiyde/Nerdiy_Products/tree/main/products/marstek_modbus_companion"
published: "2026-06-15"
language: "en"
hardware: ["WIZnet WIZ850io"]
likes: 0
views: 317
comments: 0
source: "WIZnet Makers (https://maker.wiznet.io/)"
---
# Marstek Modbus Companion
> Marstek Modbus Companion
Original author: Nerdiy (source: https://github.com/Nerdiyde/Nerdiy_Products/tree/main/products/marstek_modbus_companion)
## Components
- **WIZnet WIZ850io** x 1 ([docs](https://docs.wiznet.io/Product/ioModule/WIZ850io))
## Article
### Marstek Modbus Companion
#### 1. New Content Summary
Marstek Modbus Companion is an ESPHome-based gateway project designed to integrate the Marstek Venus E V3.0 battery storage system with Home Assistant.
The device communicates with the energy storage system through RS485 using the Modbus RTU protocol and exposes operational data to Home Assistant for monitoring and automation.
The project provides a user-friendly web interface, diagnostic tools, status LED indicators, and supports both Wi-Fi and Ethernet connectivity. The Ethernet version utilizes the W5500 controller, making it suitable for installations where stable wired networking is preferred.
**Key Technologies**
MCU: ESP32
Ethernet Controller: W5500
Communication Protocol: Modbus RTU (RS485)
Network Interface: Wi-Fi / Ethernet
Software Platform: ESPHome, Home Assistant
Target Device: Marstek Venus E V3.0 Energy Storage System (ESS)
The project demonstrates a practical integration of industrial communication protocols with modern smart-home and energy-management platforms.
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#### 2. Similar Existing Content
##### (1) Modbus TCP
**Why it is similar**
Uses the Modbus protocol for device communication.
Demonstrates network-based access to industrial data.
Utilizes WIZnet networking solutions.
Focuses on bridging field devices with IP networks.
##### (2) ESP32 + W5500 Ethernet-Based IoT Projects
**Why it is similar**
Combines ESP32 and W5500 for Ethernet connectivity.
Collects and transfers device data over a network.
Demonstrates practical IoT deployment using wired Ethernet.
Shares a similar architecture for integrating embedded devices into larger monitoring systems.
##### (3) Home Assistant Integration Projects on Maker
**Why it is similar**
Connects embedded hardware to Home Assistant.
Focuses on real-time monitoring and automation.
Uses network-enabled devices to expose sensor and system data.
Demonstrates smart-home and energy-management use cases.
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#### 3. Differences and Extension Value
While existing Modbus-related projects on Maker primarily focus on implementing Modbus TCP communication or demonstrating protocol functionality, Marstek Modbus Companion provides a complete real-world application targeting a commercial energy storage system.
Its main differentiators include:
Direct integration with a commercial ESS product (Marstek Venus E V3.0)
Native Home Assistant compatibility
Support for both Wi-Fi and W5500 Ethernet connectivity
User-oriented diagnostics and monitoring features
Energy-management-focused application rather than protocol demonstration
**Potential Extensions**
Modbus RTU-to-Modbus TCP gateway functionality
Integration with Home Assistant Energy Dashboard
Centralized monitoring of solar inverters, smart meters, and ESS devices
Industrial Energy Management System (EMS) integration
Remote monitoring through Ethernet-based infrastructure
Expansion into broader Industrial IoT and smart energy applications using WIZnet networking solutions
This project serves as a practical example of how WIZnet-powered Ethernet connectivity can be combined with Modbus-based industrial equipment and modern home energy platforms to create reliable monitoring and control solutions.
---
Source: https://maker.wiznet.io/jaden/projects/marstek-modbus-companion/