Description

The IS4350-M1 is a ready-to-use Ethernet module that turns any microcontroller with an I2C port into a Modbus TCP/IP server. It integrates the IS4350 I2C Modbus TCP/IP Server IC, the LAN8742A 10/100 Ethernet PHY, the Ethernet magnetics, ESD protection and an RJ45 connector with status LEDs on a single, pre-designed and tested board.

Designing an Ethernet interface from scratch means dealing with the PHY, its reference clock, strap configuration, impedance-controlled RMII and MDI routing, magnetics and line termination. The IS4350-M1 already contains all of this. Your design only needs to provide 3.3 V, two I2C lines and a few configuration pins.

How it Works?

The IS4350-M1 exposes 65,500 Holding Registers that work as a shared memory:

• Your microcontroller reads and writes them over I2C (Arduino, STM32, ESP32, Raspberry Pi, FPGA, etc.).
• Any Modbus client on the network (PLC, SCADA, HMI or PC) reads and writes them over Ethernet.

Your firmware writes measurements for the client to read, and reads the set-points and commands the client writes.

From your microcontroller's point of view, the module behaves like an I2C memory with 16-bit addresses and 16-bit registers.

➡️ No Ethernet driver, TCP/IP stack or Modbus library required.

Key Features

Modbus

• Function codes: 03 Read Holding Registers, 06 Write Single Register, 16 Write Multiple Registers
• 65,500 Holding Registers
• Port 502, IP by DHCP or static (default: DHCP)

Ethernet

• Onboard LAN8742A PHY, 10/100 Mbps auto-negotiation
• RJ45 with link/activity and speed LEDs

I2C

• Speeds: 100 kHz, 400 kHz and 1 MHz (selected with the SPD pin)
• Addresses: 24, 25 or 26 (selected with the ADR pin), so up to 3 modules can share one bus

Safety

• Fail-safe power-up: the server only goes online when your firmware tells it to
• Optional I2C watchdog (I2C-WDT): the server stops if your microcontroller stops refreshing it
• Optional I2C CRC protection (I2C-CRC)
• INT output pin that signals every Modbus write, so you don't have to poll
• DFT pin to restore the default network configuration
• Firmware can be updated with security patches through the provisioning UART

Mechanical

• 20 × 62 mm, 36 castellated pads on a 2.54 mm pitch
• Solder it onto your PCB as an SMD part, or fit pin headers for breadboard prototyping
• Single 3.3 V supply

Getting Started

1. Connect 3V3, GND, SCL, SDA, SPD and ADR. That's the minimum.
2. Connect the RJ45 to your network.
3. Write your initial data to the Holding Registers.
4. Write 1 to GO_ONLINE to start the Modbus server.
5. Read the assigned IP address from the IP registers and connect your Modbus client.

The user manual, Arduino example, KiCad symbol and footprint, and STEP 3D model are available at IS4350-M1 Manual. The full IS4350 datasheet is at IS4350-L64 Datasheet.

Questions?

💬 Contact us anytime for support or customization.

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.

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).