# I2C Modbus RS485 Slave Module (IS4310-485M3) The IS4310-485M3 is a ready-to-operate module integrating the Modbus RTU Slave chip IS4310 with an RS485 Transceiver. - **Seller:** [INACKS](https://www.lectronz.com/stores/inacks), Terrassa, Barcelona, Spain - **Price:** €4.80 (EUR, before shipping and taxes) - **Availability:** Sold out - **Categories:** Tools, Farming, Home automation - **Product page:** https://www.lectronz.com/products/i2c-modbus-rs485-slave-module-is4310-485m3 ## Links - [Documentation](https://inacks.com/IS4310-485M3-User_Manual_I2C_Modbus_RS485_Slave_Module_ISDOC148) ## Images ![I2C Modbus RS485 Slave Module (IS4310-485M3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NDIyODksInB1ciI6ImJsb2JfaWQifX0=--d8c190d5e0683e344a0492e54fb9555a747fa88a/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/INACKS%20IS4310-485M1%20Modbus%20RTU%20Slave.jpg) ![I2C Modbus RS485 Slave Module (IS4310-485M3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NDIyOTMsInB1ciI6ImJsb2JfaWQifX0=--28f04f2c8ca6ca7f36ace5e41152bfaca69e055b/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/INACKS%20IS4310-485M1%20Modbus%20RTU%20Slave%20Top.jpg) ![I2C Modbus RS485 Slave Module (IS4310-485M3)](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6NDIyOTcsInB1ciI6ImJsb2JfaWQifX0=--a5469c14cc73227acdfcc127a4083891c2b8f058/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/INACKS%20IS4310-485M1%20Modbus%20RTU%20Slave%20Bottom.jpg) ## Description ## Description The **IS4310-485M3** is a Modbus RS485 module that integrates a **Modbus RTU stack chip** (**IS4310**), an **RS485 transceiver** and **two daisy-chained RJ45 connectors**. By **integrating this module** into your project, you instantly get a **working Modbus RS485 interface** — just read from or write to the **IS4310's I2C memory registers**, which **directly map to the Modbus Holding Registers**. This solution **minimizes the design effort** required to integrate a Modbus RTU Slave with an RS485 physical layer. Optionally, you can **integrate** the [IS4310](https://www.inacks.com/is4310) chip **in your own design** to minimize costs and customize the connector. Example schematics can be found in the IS4310 datasheet. The **IS4310** is a chip that integrates a **Modbus RTU Slave** stack. It features an internal memory of **500 Holding Registers**, accessible by both a **microcontroller (via I2C)** and a **Modbus Master device** (e.g., PLC, computer, etc.). You can use the IS4310 in three modes: - As a **Sensor** → your microcontroller **writes** data to the chip via I2C. - As an **Actuator** → your microcontroller **reads** data from the chip via I2C. - **Mixed** → your microcontroller **reads and writes** data to the chip via I2C. Just read/write the registers you need — **no protocol stack required**. The goal of the IS4310 is to eliminate the engineering effort typically required to implement and validate Modbus RTU communication. It offers a **reliable, ready-to-use solution** that helps reduce development time and speed up your **time-to-market (TTM).** --- ## Examples and Documentation - 📄 [**Module Manual**](https://inacks.com/IS4310-485M3-User_Manual_I2C_Modbus_RS485_Slave_Module_ISDOC148) #### Modbus Chip (IS4310) used in this module - 📄 [**Datasheet**](https://inacks.com/is4310_datasheet_isdoc125) - 📘 [Online Wiki](https://inacks.gitbook.io/is4310-wiki) - 📎 [Product Flyer](https://inacks.com/is4310_flyer) ### Firmware Example Projects - 👉 [IS4310 Modbus Sensor for Arduino](https://github.com/inacks/ISXMPL4310ex6) - 👉 [IS4310 Modbus Actuator for Arduino](https://github.com/inacks/ISXMPL4310ex7) - 👉 [IS4310 Modbus Device for Nucleo-STM32](https://github.com/inacks/ISXMPL4310ex9) - 👉 [IS4310 Modbus with Python for Raspberry Pi](https://github.com/inacks/ISXMPL4310ex5) ### Others - Download Modbus RTU Master Software for Windows: [qModMaster](https://sourceforge.net/projects/qmodmaster/) --- ## How does the module work? The module provides two interfaces: - An **I2C interface** for your microcontroller, FPGA, Arduino, Raspberry Pi, etc. This is where your system **reads and writes Modbus data**. - Two **RJ45 RS485 connectors**, where you connect your Modbus Master device (computer, PLC, etc.) and the other Modbus Servers (sensors, actuators, etc.). The internal memory is composed of **504 registers**: - **500 Holding Registers** for user data. - **4 Configuration Registers** for communication settings: Modbus Slave ID, Baud Rate, Parity, Stop Bits. **The 500 Holding Registers are the key:** Whatever you write to the 500 Holding Registers via I2C will be accessible by the RS485 master device — and vice versa: whatever the RS485 master device writes to the 500 Holding Registers will be accessible by your microcontroller via I2C. --- ## Default Module Settings **Default Modbus Settings**: - Modbus Slave ID: `1` - Modbus Baud Rate: `19200 bps` - Modbus Parity: `Even` - Modbus Stop Bits: `1` **Default I2C Settings**: - I2C Slave Address: `0x11` *(fixed)* - I2C Speed: Depends on pin 7: `100 kHz` (pin 7 to GND), `400 kHz` (pin 7 to 3.3V/2), `1 MHz` (pin 7 to 3.3V) --- ## IS4310 Advantages and Features ### Firmware Advantages - 🛠️ Forget about Modbus RTU protocol handling: No need to deal with frame parsing, T1.5 and T3.5 timings, CRC or UART and Timer interrupts - ❌ No libraries needed: Just use standard I2C functions - 🧠 500 Holding Registers available for your use. - ⚡ Perfect for heavily loaded CPUs or ISR-heavy microcontrollers - 📝 Arduino, STM32, and Raspberry Pi examples available - 🧪 Evaluation board available to make some tests in Arduino/Nucleo and Raspberry Pi form factor - ⏱️ Save firmware engineering time ### Hardware Advantages - 🔌 Save pins on your microcontroller: No need to sacrifice any UART pins as it uses I2C, a shared interface - 🧘 Reduce the CPU load of your microcontroller - 💾 Reduce Flash and RAM memory footprint - ⚙️ Save microcontroller resources (UART, Timers, etc.) - 🗂️ Schematic design examples available for RS485, RS485-ISOLATED, RS232 ### Compatibility Advantages ## - 🔄 Great for non-deterministic systems (like Raspberry Pi and single-board computers) - 💡 Compatible with 5V I2C serial interfaces - 🔋 Compatible with 5V RS485 transceivers - 🏎️ Supports I2C speeds: 100kHz, 400kHz, and 1MHz - 🖥️ Ideal for FPGA designs ### Production Advantages ## - 🧷 Easy-to-solder SO8N package - 📦 Reels available for pick-and-place machines ### Commercial Advantages ## - 🚀 Speeds up development - ⚙️ Faster prototyping - 🏁 Shorter time-to-market --- ## Pick'n'Place 📦 **Reels available** at **lower prices** for high-volume orders. Contact us. --- ## Questions? 💬 Contact us anytime for support. [www.inacks.com](http://www.inacks.com) --- *This company and the products provided herein are developed independently and are not affiliated with, endorsed by, or associated with any official protocol or standardization entity. All trademarks, names, and references to specific protocols remain the property of their respective owners.* ## Shipping policy We ship all products from Barcelona via UPS within 1–2 business days. A tracking number is provided. Transit time is typically less than one week worldwide (excluding handling time).