2 Digital Output
Isolated 2DO Modbus Remote I/O Module
Compact Modbus RTU remote I/O module with two isolated digital SSR outputs, including one high-speed PWM-capable output channel.
Key Features
- 2 Isolated Digital SSR Outputs, 0~60V DC, 1.0 Amp
- 1 High speed Output with Variable Frequency and Duty
- Modbus RTU over RS-485
- Dip address switch for address selection from 1 to 15
- Wide Supported baud rates from 300 to 115200
- DIN Rail mount support
- Dimensions: 60mm x 50mm x 20mm (L x W x H)
ModViz – Modbus Configuration & Visualization Tool
ModViz is a powerful yet simple configuration and visualization tool designed to work seamlessly with Veawe Modbus I/O modules. It enables engineers, system integrators, and technicians to quickly configure, monitor, and test field devices through an intuitive graphical interface.
The software can be downloaded from https://veawe.io/modviz/
Ordering Information
| Product Code | Description |
|---|---|
| MIO-ISO-2DO | 2-Channel Isolated Digital Output Module (5~24V compatible) |
| UIO-4DI-4DO | 4-Channel Digital Input / 4-Channel Digital Output Module |
| UIO-8DO | 8-Channel Digital Output Module |
| UIO-12DI-12DO | 12-Channel Digital Input / 12-Channel Digital Output Module |
| UIO-24DO | 24-Channel Digital Output Module |
| UIO-24DI-24DO | 24-Channel Digital Input / 24-Channel Digital Output Module |
Applications
- Industrial Automation – Drive relays, contactors, and solenoids from a Modbus master in PLC and SCADA systems
- Process Control – Switch pumps, motors, valves, and other on/off actuators remotely
- Energy & Utilities – Trigger alarms, indicator lamps, or breaker trip/close signals
- Building Management – Control HVAC equipment, lighting circuits, and access control devices
- Remote Monitoring – Ideal for distributed installations requiring remote on/off control over Modbus RTU
Specifications
| Parameter | Value |
|---|---|
| Mounting | DIN rail |
| Dimensions | 60 mm x 50 mm x 20 mm (L x W x H) |
Electrical Specifications
| Parameter | Value |
|---|---|
| Supply Voltage | 12–24V DC or USB 5V |
| Communication Port | RS-485 |
Input/Output Specifications
| Parameter | Value |
|---|---|
| Channel Count | 2 |
| Output Type | Polarity Free AC/DC Solid State Relay (SSR) |
| Output Voltage Range | Max 60V AC Peak or 60V DC |
| Max Load Current | 1.0 A |
| High Speed Output | 1 channel (Y2), PWM configurable up to 1000 Hz |
| Output Delay Resolution | 10 ms (1 count = 10 ms, up to 655.35 s) |
Isolation & Protection Specifications
| Parameter | Value | Notes / Description |
|---|---|---|
| Supply Reverse Polarity Protection | Integrated | Series protection diode (continuous protection, zero reverse leakage) |
| Supply Isolation | Non-Isolated | Common ground between input power, internal circuitry |
| Output Isolation | 2.5kVrms | Opto isolated outputs with other circuitry |
| Transient Voltage Clamping | Up to 600W | Clamps overvoltage spikes (10/100 µs peak pulse rating) |
| EMC & Immunity Standards | Class-Compliant | Meets IEC 61000-4-2 (ESD), IEC 61000-4-4 (EFT), & IEC 61000-4-5 (Surge) |
| RS-485 Bus ESD Protection | 15kV HBM/Air | IEC61000-4-2 Integrated high-ESD protected transceiver on A/B lines |
Mechanical Dimensions
Terminal Details
| Pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|
| Signal | 24V+ | 24V- | A+ | B- | Y1~ | Y1~ | Y2~ | Y2~ |
Wiring Diagrams
Note: All images and connection diagrams shown are for illustrative purposes only and may differ from the actual product.
Communication Interface
| Protocol | Physical Layer | Default Baud Rate | Default Format |
|---|---|---|---|
| Modbus RTU | RS-485 | 19200 | 8N1 |
Basic Process Registers
| Signal | Address | Type | Description |
|---|---|---|---|
| DO1–DO2 | 00001–00002 | Bit | Digital output control and status |
Supported Modbus Function Codes
| Read | Write |
|---|---|
| 01 – Read Coils | 05 – Write Single Coil |
| 02 – Read Discrete Inputs | 06 – Write Single Register |
| 03 – Read Holding Registers | 15 – Write Multiple Coils |
| 04 – Read Input Registers | 16 – Write Multiple Registers |
Register Map Overview
| Function | Address Range | Type | Description |
|---|---|---|---|
| Discrete Inputs | 10001–10002 | Bit | DO1 to DO2 live digital output status |
| Coils | 00001–00002 | Bit | DO1 to DO2 output control and status |
| Coils | 00401–00402 | Bit | Pending DO1 to DO2 state while ON/OFF delay timer is active |
| Coils | 00502 | Bit | HSO2 (Y2) output control and status |
| Holding Registers | 40101 | int16 | Modbus server (slave) address (switch value) |
| Holding Registers | 40102 | int16 | Baud rate selection |
| Holding Registers | 40103 | int16 | Serial format selection |
| Holding Registers | 40104 | int16 | Serial device mode. 0 = Server (slave), 1 = Client (master) |
| Holding Registers | 40105 | int16 | Remote read/write poll interval. Example: 10 = 1 second |
| Holding Registers | 40106 | int16 | Watchdog interval. Example: 10 = 1 second |
| Holding Registers | 40107 | int16 | Watchdog action. 0 = Modbus Watchdog Disabled, 1 = Reset Outputs on Modbus Watchdog Expire |
| Holding Registers | 40401–40402 | int16 | DO1 to DO2 ON delay |
| Holding Registers | 40451–40452 | int16 | DO1 to DO2 OFF delay |
| Holding Registers | 40502 | int16 | High Speed Output (Y2) mode |
| Holding Registers | 40512–40513 | int32 | High Speed Output (Y2) PWM frequency |
| Holding Registers | 40532 | int16 | High Speed Output (Y2) PWM duty % |
Detailed Register Tables
Discrete Inputs (1xxxx)
Digital Live Output Status
| Address | Description |
|---|---|
| 10001–10002 | DO1 to DO2 live digital output status |
Coils (0xxxx)
Output Control
| Address | Description |
|---|---|
| 00001–00002 | DO1 to DO2 output control and status |
| 00502 | HSO2 Output Control and status |
Pending Output State
| Address | Description |
|---|---|
| 00401–00402 | Pending DO1 to DO2 state while ON/OFF delay timer is active |
This indicates there is pending Output which needs to be on when its Delay timer expires Forcing this coil will ignore the Delay time and switch the DO to ON state.
Holding Registers (4xxxx)
Digital Output Delay Configuration
| Address | Type | Description |
|---|---|---|
| 40401–40402 | int16 | DO1 to DO2 ON delay |
| 40451–40452 | int16 | DO1 to DO2 OFF delay |
| Delay Resolution: | ||
| 1 = 10ms, | ||
| 100 = 1 second | ||
| Maximum value: - 65535 = 655.35 seconds |
High Speed Output Configuration
| Address | Type | Description |
|---|---|---|
| 40502 | int16 | Y2 (HSO) mode. 0 = Digital output (master controlled), 1 = PWM continuous, 2 = PWM controlled |
| 40512–40513 | int32 | Y2 (HSO) PWM frequency, 0–1000 Hz |
| 40532 | int16 | Y2 (HSO) PWM duty %, 0–100.0% (raw 0–1000) |
Communication Settings
| Address | Type | Description |
|---|---|---|
| 40101 | int16 | Modbus server (slave) address (switch value) |
| 40102 | int16 | Baud rate selection |
| 40103 | int16 | Serial format selection |
| 40104 | int16 | Serial device mode. 0 = Server (slave), 1 = Client (master) |
| 40105 | int16 | Remote read/write poll interval. Example: 10 = 1 second |
| 40106 | int16 | Watchdog interval. Example: 10 = 1 second |
| 40107 | int16 | Watchdog action. 0 = Modbus Watchdog Disabled, 1 = Reset Outputs on Modbus Watchdog Expire |
Modbus Address (40101)
This is set using the rotary or DIP switches.
Baud Rate Register (40102) and Serial Format Register (40103)
| Value | Baud Rate | Value | Baud Rate | Value | Format |
|---|---|---|---|---|---|
| 0 | 300 | 7 | 9600 | 0 | 8N1 |
| 1 | 600 | 8 | 14400 | 1 | 8E1 |
| 2 | 1200 | 9 | 19200 | 2 | 8O1 |
| 3 | 1800 | 10 | 38400 | 3 | 8N2 |
| 4 | 2400 | 11 | 57600 | 4 | 8E2 |
| 5 | 4800 | 12 | 62500 | 5 | 8O2 |
| 6 | 7200 | 13 | 115200 |
Default: 19200 baud, 8N1.
Default Settings
| Setting | Default |
|---|---|
| Slave Address | As per switch position |
| Baud Rate | 19200 |
| Serial Format | 8N1 |
Configuration Settings
Default Mode
Default mode is useful when communication settings are unknown.
When the rotary address switch is set to 00:
- Server address = 1
- Baud rate = 19200
- Serial format = 8N1
Changing to default mode does not overwrite stored settings. Stored settings remain unchanged until written through Modbus.
Watchdog Action
The Bus Watchdog automatically resets all outputs to their initial safe state if communication with the Modbus client is lost. This helps ensure safe operation during cable disconnection, client failure, or other communication faults.
Configurable timeout: 1 to 600 seconds (100 ms resolution).
LED Indications and Diagnostics
| LED | Description |
|---|---|
| Tx | RS-485 transmit status and run blink every 2 sec when idle |
| DO1–DO2 | Digital Output active status |
Revision History
| Revision | Date | Changes |
|---|---|---|
| Rev 1.0 | 2026-08-10 | Initial datasheet, HW Version = 3, FW Version = 2 |
Get the latest version of this datasheet : click here..
Support
Website: www.veawe.io
Email: info@veawe.io