Expand Your Digital I/O with One Versatile Series

Modern automation systems often require a combination of digital signal monitoring and remote switching. From industrial machines and PLC systems to building automation and security equipment, engineers need a practical way to collect input signals and control multiple outputs without excessive wiring.

The Eletechsup 23IOA08, 23IOB16, 23IOC24, and 23IOE48 series provides a flexible solution with digital inputs, NPN transistor outputs, and standard RS485 Modbus RTU communication.

With four channel-count options, optically isolated inputs, configurable output modes, and support for multi-module systems, the 23IO series is designed for projects that need reliable, organized digital I/O expansion.

Official product page:
https://eletechsup.com/products/23ioa08-23iob16-23ioc24-23ioe48-8-16-24-32-48ch-multifunction-rs485-remote-io-module-plc-di-do-expansion-board-din-rail-box-standard-modbus-rtu-protocol

1. Four Models to Match Different I/O Requirements

One of the main advantages of the 23IO series is its range of channel capacities. Users can select a model based on the number of digital signals their application requires.

• 23IOA08: 8 digital inputs and 8 digital outputs

• 23IOB16: 16 digital inputs and 16 digital outputs

• 23IOC24: 24 digital inputs and 24 digital outputs

• 23IOE48: 48 digital inputs and 48 digital outputs

From compact control projects to larger distributed installations, the series offers a consistent product family with different I/O capacities.

This helps system integrators select an appropriate module without changing to a completely different product architecture as their channel requirements grow.

2. Combined Digital Input Monitoring and Output Control

The 23IO series combines digital input acquisition and digital output control in the same module.

The input channels can monitor compatible sensors, switches, and equipment status signals. The output channels can then control compatible low-current electronic loads or provide switching signals to other control equipment.

Typical applications include:

• PLC digital I/O expansion

• Industrial equipment monitoring

• Remote switch control

• Building and home automation

• Security and surveillance systems

• PTZ camera control interfaces

• LED indicator and compatible lighting control

• Automatic curtain control

• Distributed sensor and switch monitoring

By combining inputs and outputs in one module, users can reduce the number of separate interface boards required for many applications.

3. Optically Isolated Digital Inputs

Electrical isolation is an important feature when connecting field sensors and external signals to electronic control systems.

The 23IO series provides optically isolated digital inputs to help separate field input circuits from the module's internal electronics.

NPN input configurations are available, and selected versions also offer PNP input options. This gives users flexibility when matching the module to their sensor wiring and control system.

Optical isolation can help reduce the direct transfer of electrical disturbances between the input side and internal circuitry. Correct grounding, power supply selection, wiring practices, and appropriate surge protection remain important for reliable operation.

Before ordering, confirm the input configuration of the exact model and version you intend to use.

4. NPN Transistor Outputs for Electronic Switching

The 23IO series uses NPN Darlington transistor outputs, based on the ULN2803 output design, rather than mechanical relay contacts.

Each output channel supports a maximum load current of 300 mA, subject to the applicable electrical and thermal limitations.

This output design is useful for applications that require electronic switching of compatible low-current loads, including:

• Indicator lamps and LEDs with suitable current limiting

• Compatible control inputs

• Low-current interface circuits

• Electronic switching signals

• Compatible auxiliary control modules

Semiconductor outputs do not have mechanical relay contacts, making them suitable for applications where electronic switching is preferred.

However, the outputs are not intended to replace high-current mechanical relays. Check the load voltage, current, polarity, and inductive-load requirements before connecting equipment. External driver stages may be required for higher-current loads.

5. Standard RS485 Modbus RTU Communication

The 23IO series uses RS485 communication with the Modbus RTU protocol, allowing integration with compatible PLCs, industrial controllers, computers, and automation software.

The documented communication settings include:

• Default baud rate: 9,600 bps

• Selectable baud rates: 1,200 to 115,200 bps

• Modbus function codes covering supported read and write operations

The product documentation describes two Modbus command modes with different supported function codes. This gives developers options when integrating the modules into existing control software.

RS485 communication is especially useful for distributed I/O installations because multiple compatible devices can communicate over a shared serial bus, reducing the need to route every individual signal directly to a central controller.

6. Multiple Output Control Modes

The 23IO series supports several output control modes, helping users adapt the module to different automation tasks.

Open/Close control: Switch an output on or off through a supported command.

Momentary control: Activate an output temporarily.

Self-locking control: Change an output state and retain that state until another command changes it.

Interlocking control: Apply interlocking behavior to coordinate output states.

Delay control: Use a configurable delay for timed switching operations.

The documented command mode supports delays of up to 255 seconds.

These features can be useful for timed switching, remote activation, lighting control, and other applications that require more than simple on/off commands.

The input ports can also be configured to control output ports on another compatible board through the RS485 bus, provided that the relevant registers and command mode are configured correctly.

7. Support for Multi-Module Systems

Some projects need far more I/O points than a single board can provide. The 23IO series supports multi-device configurations, with the official documentation specifying up to 64 devices in parallel in the applicable Modbus command mode.

This makes the series suitable for larger systems where I/O points are distributed across different machines, zones, or control panels.

Potential applications include:

• Multi-zone building automation

• Distributed industrial control

• Centralized monitoring of multiple machines

• Remote switching and status acquisition

• Large sensor and switch installations

The actual system capacity depends on device addressing, the selected command mode, RS485 bus wiring, communication timing, and the capabilities of the host controller.

8. Flexible DC Power Supply and DIN-Rail Enclosure

The modules operate from a DC supply within the specified 6.5–30 V range, making them suitable for compatible 9 V, 12 V, and 24 V systems.

A DIN-rail enclosure option is available to simplify installation inside suitable control cabinets.

The approximate enclosed dimensions vary with the channel count:

Model	I/O channels	Enclosed dimensions
23IOA08	8 DI + 8 DO	85 × 80 × 30 mm
23IOB16	16 DI + 16 DO	130 × 80 × 30 mm
23IOC24	24 DI + 24 DO	173 × 80 × 30 mm
23IOE48	48 DI + 48 DO	293 × 80 × 30 mm

This range of sizes allows users to balance the number of I/O points against the available installation space.

9. Why Choose the Eletechsup 23IO Series?

The 23IO series combines digital input monitoring, NPN transistor output control, and standard RS485 communication in one remote I/O platform.

Its key advantages include:

• Four channel-count options from 8 to 48 inputs and outputs

• Optically isolated digital inputs

• NPN transistor outputs rated up to 300 mA per channel

• NPN input options, with PNP input available on selected versions

• Standard RS485 Modbus RTU communication

• Multiple output control modes

• Configurable serial communication speeds

• Support for multi-module installations

• Optional DIN-rail enclosure

For engineers, system integrators, and automation developers, the 23IO series offers a practical way to expand digital I/O capacity while keeping field signal acquisition and low-current output control organized in a compact module.

Choose the Right 23IO Model for Your Project

Choose the 23IOA08 for smaller systems, the 23IOB16 for medium-sized installations, the 23IOC24 for applications requiring 24 input and output channels, or the 23IOE48 when higher channel density is required.

Before ordering, verify the input type, wiring, output load requirements, Modbus command mode, and enclosure configuration against the official product documentation.

Explore the Eletechsup 23IO Series:
https://eletechsup.com/products/23ioa08-23iob16-23ioc24-23ioe48-8-16-24-32-48ch-multifunction-rs485-remote-io-module-plc-di-do-expansion-board-din-rail-box-standard-modbus-rtu-protocol

Note: These modules use transistor outputs rather than mechanical power relays. Always check the applicable datasheet and wiring instructions before connecting field equipment.