2 Digital Isolated Inputs
Isolated 2DI Modbus Remote I/O Module
Compact Modbus RTU remote I/O module with two isolated digital inputs, pulse counting, RPM calculation.
Key Features
- 2 Isolated Digital Inputs, 5\~24V compatible
- 2 High speed Production counter and RPM measurement
- All Inputs has latched status, Never miss an input change
- All Inputs has individual counter functions with retentive memory storage
- 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-2DI | 2-Channel Isolated Digital Input Module (5~24V compatible) |
| UIO-4DI-4DO | 4-Channel Digital Input / 4-Channel Digital Output Module |
| UIO-8DI | 8-Channel Digital Input Module |
| UIO-12DI-12DO | 12-Channel Digital Input / 12-Channel Digital Output Module |
| UIO-24DI | 24-Channel Digital Input Module |
| UIO-24DI-24DO | 24-Channel Digital Input / 24-Channel Digital Output Module |
| UIO-48DI | 48-Channel Digital Input Module |
Applications
- Industrial Automation – Monitor isolated digital signals from sensors, switches, and field devices in PLC and SCADA systems
- Motor & Machine Monitoring – Measure RPM and RPS from proximity sensors or encoders on motors, conveyors, and rotating equipment
- Production Counting – Track production output with retentive high-speed counters that survive power cycles
- Process Monitoring – Detect and latch digital input state changes such as limit switches, float switches, or alarm contacts
- Building Management – Integrate isolated digital status signals for HVAC, access control, and utility monitoring
- Remote Monitoring – Ideal for distributed installations requiring electrically isolated digital inputs and pulse-rate measurement
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 | 12V \~ 24V DC or USB 5V |
| Digital Inputs Range | 5\~24V compatible |
| Communication Port | RS-485 |
Input/Output Specifications
| Parameter | Value |
|---|---|
| Channel Count | 2 |
| Signal Range | 5\~24V compatible |
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 |
| Input Isolation | 2.5kVrms | Opto isolated inputs 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- | X1+ | X1- | X2+ | X2- |
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 |
|---|---|---|---|
| DI1–DI2 | 10001–10002 | Bit | DI1 to DI2 live digital input 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 | DI1 to DI2 live digital input status |
| Discrete Inputs | 10201–10202 | Bit | DI1 to DI2 latched status, auto clears on read |
| Coils | 00251–00252 | Bit | Reset DI1 to DI2 slow counter |
| Coils | 00801–00802 | Bit | Reset production counter, DI1 to DI2 |
| Input Registers | 30251–30252 | int16 | DI1 to DI2 slow counter (1 kHz) |
| Input Registers | 30801–30802 | int16 | DI1 to DI2 RPS value |
| Input Registers | 30811–30812 | int16 | DI1 to DI2 RPM value |
| Input Registers | 30821–30824 | int32 | DI1 to DI2 production counter |
| 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 | 40801–40802 | int16 | DI1 to DI2 mode |
| Holding Registers | 40811–40812 | int16 | DI1 to DI2 pulses per revolution (PPR) |
Detailed Register Tables
Discrete Inputs (1xxxx)
Digital Live Input Status
| Address | Description |
|---|---|
| 10001–10002 | DI1 to DI2 live digital input status |
Digital Input Latched Alarm Status
| Address | Description |
|---|---|
| 10201–10202 | DI1 to DI2 latched alarm status; auto clears on read |
- Latched input status stays high even after the input goes low and auto clears only after the master reads this bit. This makes sure no input status is missed by the controller
Coils (0xxxx)
Slow Counter Reset
| Address | Description |
|---|---|
| 00251–00252 | Reset DI1 to DI2 slow counter |
Production Counter Reset
| Address | Description |
|---|---|
| 00801–00802 | Reset production counter for High speed counters, DI1 and DI2 |
Input Registers (3xxxx)
Digital Inputs Slow Counter Values
| Address | Type | Description |
|---|---|---|
| 30251–30252 | int16 | DI1 to DI2 slow counter (1 kHz) |
Note : Retentive memory on power cycles
The DI change are counted and stored in these registers
High Speed Counter Values
| Address | Type | Description |
|---|---|---|
| 30801–30802 | int16 | DI1 to DI2 RPS value |
| 30811–30812 | int16 | DI1 to DI2 RPM value |
| 30821–30824 | int32 | DI1 to DI2 production counter |
Holding Registers (4xxxx)
High Speed Counter Configuration
| Address | Type | Description |
|---|---|---|
| 40801–40802 | int16 | DI1 to DI2 mode |
| 40811–40812 | int16 | DI1 to DI2 pulses per revolution (1\~65535) |
DI Mode Values:
0 = Normal digital input
1 = RPM / RPS measurement
2 = Production counter
Communication Settings
| Address | Type | Description |
|---|---|---|
| 40101 | int16 | Modbus server (slave) address (switch value) |
| 40102 | int16 | Baud rate selection |
| 40103 | int16 | Serial format selection |
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:
- Slave 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.
LED Indications and Diagnostics
| LED | Description |
|---|---|
| Tx | RS-485 transmit status and run blink every 2 sec when idle |
| DI1–DI2 | Digital Input 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