DIO-430-R1 Relay module

Overview

The DIO-430-R1 is a configurable smart digital I/O module designed for digital input monitoring and relay-based output control in building automation, lighting, HVAC, alarms, and general control systems. It offers 4 opto-isolated digital inputs, 3 high-current SPDT relays, 3 user buttons, and 3 configurable user LEDs. All I/O channels are individually configurable, allowing flexible logic such as toggle, pulse, manual override, and alarm indication.

It connects via RS-485 (Modbus RTU) to a MicroPLC, MiniPLC, or any compatible controller, and can also integrate with Home Assistant (ESPHome) or SCADA/PLC systems. Configuration and diagnostics are performed through a driverless Web Serial interface via USB-C, using the browser-based WebConfig Tool. The module supports both master-controlled and standalone local logic modes.

Getting Started

Quick Setup Process

1. Mount & Wire – Install on 35mm DIN rail, connect 24V DC power, sensors, and relay loads.

2. Configure – Plug in USB-C, open the WebConfig tool in Chrome/Edge, set Modbus address and I/O mapping.

3. Integrate – Connect to your controller via RS-485 and start automation.

What You Need

• DIO-430-R1 module

• 24V DC SELV power supply

• RS-485 cable (twisted pair)

• USB-C cable for configuration

• Chromium-based browser (Chrome/Edge)

Web Configuration Steps

1. Connect USB-C to module and PC

2. Open https://www.home-master.eu/configtool-dio-430-r1

3. Click "Connect" and select serial port

4. Set Modbus address (default: 3) and baud rate (default: 19200 8N1)

5. Configure input actions, relay mapping, LED modes, and button functions

6. Settings save automatically to flash

Tech Specs

Documentation

The DIO-430-R1 is open-source hardware! You can build your own board using the following files:

Hardware Design Files

• Field Board Schematic: DIO-430-R1-FieldBoard.pdf

• MCU Board Schematic: DIO-430-R1-MCUBoard.pdf

• System Block Diagram: DIO_SystemBlockDiagram.png

• Control Board Diagram: ControlBoard_Diagram.png

• Relay Board Diagram: RelayBoard_Diagram.png

Firmware & Software

• Firmware Source Code: DIO-430-R1/Firmware/

• WebConfig Tool: ConfigToolPage.html

• ESPHome Integration Package: default_dio_430_r1_plc.yaml

Mechanical Files

• Dimensional Drawing: DIODimensions.png

All design files and documentation are available in the HomeMaster GitHub repository.

Input and Output

Digital Inputs (4 channels)

• Isolated inputs compatible with dry contacts 24V signals

• Individual enable/invert settings per channel

• Configurable actions: None, Toggle, or Pulse

• Target mapping to individual relays or all relays

• PTC + TVS protection on each channel

Relay Outputs (3 channels)

• SPDT contacts (NO/NC/COM)

• 16A @ 250V AC rating

• Individual enable/invert settings

• Controlled via Modbus coils or local input mapping

• RC/MOV snubbers recommended for inductive loads

User Interface

• 3 Buttons: Configurable for relay override (toggle function)

• 3 LEDs: Configurable steady or blink modes, linked to relay status

• Status LEDs: PWR (power), TX/RX (Modbus activity)

Communication Interfaces

• Protocol: Modbus RTU

• Role: Slave device

• Default Settings: Address 3, 19200 baud, 8 data bits, No parity, 1 stop bit

• Supported Functions: Read Coils (0x01), Read Discrete Inputs (0x02), Read Holding Registers (0x03), Read Input Registers (0x04), Write Single Coil (0x05), Write Single Register (0x06)

Modbus Address Map

Coils (Read/Write) - Function Codes 0x01, 0x05

Discrete Inputs (Read Only) - Function Code 0x02

Holding Registers (Read/Write) - Function Codes 0x03, 0x06

Input Registers (Read Only) - Function Code 0x04

Home Assistant & ESPHome Integration Guide

Overview

The DIO-430-R1 integrates seamlessly with Home Assistant via ESPHome using the Modbus RTU protocol. This guide covers both quick integration using our pre-built package and manual configuration for advanced users.

Prerequisites

Before starting, ensure you have:

1. ESPHome device (HomeMaster MiniPLC/MicroPLC or any ESP32/ESP8266 with RS-485)

2. RS-485 connection between ESP device and DIO-430-R1

3. 24V power to DIO-430-R1 module

4. Home Assistant with ESPHome add-on installed

Configure Your ESPHome Device

Add this to your ESPHome YAML configuration:

# RS-485 Configuration
uart:
  id: uart_modbus
  tx_pin: GPIO17
  rx_pin: GPIO16
  baud_rate: 19200
  parity: NONE
  stop_bits: 1

modbus:
  id: modbus_bus
  uart_id: uart_modbus

# Import DIO-430-R1 Package
packages:
  dio_430_r1:
    url: https://github.com/isystemsautomation/HOMEMASTER
    ref: main
    files:
      - path: DIO-430-R1/Firmware/default_dio_430_r1_plc/default_dio_430_r1_plc.yaml
        vars:
          dio_prefix: "Staircase"  # Custom name for your entities
          dio_id: staircase_module  # Unique internal ID
          dio_address: 3  # Must match WebConfig Modbus address
    refresh: 1d

Customize Variables

• dio_prefix: Appears in entity names (e.g., "Staircase Relay 1")

• dio_id: Must be unique if adding multiple DIO modules

• dio_address: Set to match your DIO-430-R1 Modbus address (default: 3)

Multiple DIO Modules

For additional modules, duplicate the package block with unique IDs:

packages:
  dio_lights:
    url: https://github.com/isystemsautomation/HOMEMASTER
    ref: main
    files:
      - path: DIO-430-R1/Firmware/default_dio_430_r1_plc/default_dio_430_r1_plc.yaml
        vars:
          dio_prefix: "Kitchen"
          dio_id: kitchen_module
          dio_address: 4
    refresh: 1d

  dio_hvac:
    url: https://github.com/isystemsautomation/HOMEMASTER
    ref: main
    files:
      - path: DIO-430-R1/Firmware/default_dio_430_r1_plc/default_dio_430_r1_plc.yaml
        vars:
          dio_prefix: "HVAC"
          dio_id: hvac_module
          dio_address: 5
    refresh: 1d

Programming

Supported Development Environments

• Arduino IDE with RP2350 support

• PlatformIO with RP2350 toolchain

• MicroPython (community builds available)

Firmware Flashing

1. Connect USB-C to PC

2. Hold Buttons 2 + 3 to enter BOOT mode

3. Upload via:

   • UF2 drag-and-drop to mounted drive, OR

   • PlatformIO/Arduino IDE upload

4. Press Buttons 1 + 3 for hardware reset if needed

Pin Mapping (Default Firmware)

Pin Name	GPIO	Function
IN1	GPIO6	Digital Input 1
IN2	GPIO11	Digital Input 2
IN3	GPIO12	Digital Input 3
IN4	GPIO7	Digital Input 4
RLY1	GPIO10	Relay 1 Driver
RLY2	GPIO9	Relay 2 Driver
RLY3	GPIO8	Relay 3 Driver
BTN1	GPIO1	Button 1
BTN2	GPIO2	Button 2
BTN3	GPIO3	Button 3
LED1	GPIO13	User LED 1
LED2	GPIO14	User LED 2
LED3	GPIO15	User LED 3
RS485_TX	GPIO4	RS-485 Transmit
RS485_RX	GPIO5	RS-485 Receive

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