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Welcome to the INACKS IS4350 I2C Modbus TCP/IP Server IC Wiki

I2C Modbus TCP/IP Server with 65,500 Holding Registers In a Single Chip

This information is provided for general informational and presentation purposes only and must not be considered a substitute for the official documentation. For engineering, design, validation, or production use, always refer to the latest datasheet and documentation available on the manufacturer's official website.

Datasheet

Download the latest revision of the datasheet: Download IS4350 Datasheet

Buy Now

Visit our product page to place your order: https://www.inacks.com/is4350

The IS4350 is also available as a ready-to-use module with an Ethernet PHY and RJ45 connector (IS4350-M1): https://www.inacks.com/is4350-m1

General Description

The IS4350 is an integrated circuit that implements a Modbus TCP/IP server stack. It provides 65,500 Holding Registers of internal memory for application use, accessible both by your microcontroller via I2C and by any Modbus client (PLC, computer, etc.) over the network. The IS4350 interfaces with Ethernet through an external LAN8742A PHY transceiver.

The IS4350 reduces the engineering time and cost associated with implementing and testing Ethernet and Modbus TCP/IP communication, offering a reliable, ready-to-use solution that shortens product time-to-market. It requires no specialized libraries; communication is handled using standard I2C read and write commands.

The IS4350 internal firmware can be updated to keep it current with the latest security patches, and it implements safety mechanisms such as I2C CRC protection (I2C-CRC), an I2C watchdog timer (I2C-WDT), and fail-safe power-up.

The device operates at 3.3 V and is housed in an LQFP64 (10×10 mm) package.

How It Works

The IS4350 features two communication interfaces:

  • An I2C interface for your microcontroller ➜ this is where your system reads/writes Modbus data.

  • An RMII interface for the LAN8742A Ethernet PHY transceiver ➜ this is the network side that connects to a PLC, computer, or machine.

The 65,500 Holding Registers act as a shared memory bank between the Modbus client (PLC) and your microcontroller. In a motor controller, for example, the PLC can write the desired motor speed to some Holding Registers and read the motor's power consumption from others.

Essentially, the IS4350 operates as an I2C memory device integrated with the Ethernet and Modbus TCP/IP stack, where the internal memory map is directly exposed as Holding Registers.

Getting started is straightforward. For example, for a Modbus TCP/IP temperature sensor:

  1. Write the temperature value to Holding Register 0 (HOLD_0) and update it periodically.

  2. Enable the Modbus server by writing 1 via I2C to the GO_ONLINE register.

The Modbus server is now online, and the temperature value is accessible to any Modbus client. By default, the IS4350 is configured in DHCP mode, so no Ethernet configuration is required.

Applications

  • Industrial Sensors and Transmitters (Temperature, Pressure, Flow, Level)

  • Actuator and Motor Controllers

  • Remote I/O Modules

  • Energy Meters and Power Monitors

  • Building Automation and HVAC Controllers

  • Data Acquisition and Test Equipment

Main Advantages

  • No TCP/IP or Modbus stack to develop, test, or maintain.

  • Simple integration: standard I2C reads and writes, no libraries required.

  • Lower microcontroller load: no Ethernet ISRs, timers, or stack memory.

  • Only two microcontroller pins (SDA and SCL).

Safety

  • IS4350 can be updated with the latest security patches.

  • Optional I2C Watchdog Timer (I2C-WDT).

  • Optional I2C CRC Protection (I2C-CRC).

  • Fail-Safe Power-Up.

Modbus, Ethernet and I2C Characteristics

  • 65,500 Holding Registers available.

  • Implemented Function Codes:

    • 03 – Read Holding Registers

    • 06 – Write Single Register

    • 16 – Write Multiple Registers

  • Modbus Unit Identifier: 0xFF (responds to any, as defined in the standard).

  • Modbus server port: 502.

  • IP configuration: DHCP or static (default: DHCP).

  • Ethernet speed: 10/100 Mbps.

  • MAC address: manual, generated from the IS4350 serial number, random, or loaded from an external EUI-48 EEPROM (AT24MAC402-STUM-T).

  • I2C speeds: 100 kHz, 400 kHz, and 1 MHz.

  • 3 configurable I2C addresses: 24, 25, 26.

Ordering Information

Orderable Device
Status
Package
Pins
Temperature Range

IS4350-L64I

ACTIVE

LQFP64 (10×10 mm)

64

I (Industrial) -40 °C to 85 °C

IS4350-M1I

ACTIVE

Module (20×62 mm)

36 + Ethernet Connector

I (Industrial) -40 °C to 85 °C

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