Monitor More Signals with Fewer I/O Modules

Modern automation systems often need to monitor dozens of switches, sensors, status signals, and digital control points. Connecting all these signals individually to a PLC can increase wiring complexity, installation costs, and the amount of space required in a control cabinet.

The Eletechsup 24DIA16, 24DIB32, and 24DIC48 series offers a practical solution for digital signal acquisition through RS485 communication. With 16, 32, or 48 digital input channels, optical isolation, and Modbus RTU support, these modules help engineers collect multiple field signals and integrate them into centralized monitoring and control systems.

Official product page: https://eletechsup.com/products/24dia16-24dib32-24dic48-16-32-48ch-di-npn-pnp-digital-switch-plc-io-expansion-3000vdc-optical

1. High-Density Digital Input Expansion

The biggest advantage of the 24DI series is its ability to collect many digital signals through a single module.

• 24DIA16: 16 digital input channels

• 24DIB32: 32 digital input channels

• 24DIC48: 48 digital input channels

Instead of using multiple small input boards, users can select a model that matches the number of signals required by their application.

This is particularly useful when monitoring many switches, sensor outputs, equipment status signals, or digital control points across a machine or building.

For systems with numerous field signals, higher channel density can simplify wiring organization and reduce the number of separate I/O devices required.

2. NPN and PNP Digital Signal Compatibility

Industrial sensors and switching devices are available in different output configurations. Choosing an input module that matches the sensor type is essential for reliable signal acquisition.

The 24DI series supports NPN and PNP digital input configurations, depending on the model and version. The inputs can accommodate compatible 3.3 V, 5 V, 12 V, and 24 V digital signals.

Potential signal sources include:

• Proximity sensors

• Limit switches

• Push buttons and contact switches

• Equipment running or fault signals

• Door and access status sensors

• Digital outputs from compatible controllers

This flexibility makes the series useful for a variety of industrial and building automation installations.

Important: Confirm the exact NPN or PNP configuration of the selected model before ordering. Sensor wiring and signal voltage must match the input circuit.

3. Optical Isolation for Better Electrical Separation

Electrical isolation is an important consideration when connecting external sensors and field wiring to a control system.

The 24DI series uses optical isolation for its digital inputs. The published product specifications also identify optical isolation on the RS485 communication interface.

The listed isolation ratings are up to 5,000 VDC for digital inputs and 3,000 VDC for RS485 communication isolation.

Optical isolation helps separate connected signal circuits from the module's internal electronics and can reduce the risk of electrical disturbances being directly coupled between those circuits.

This makes the series suitable for applications where multiple external signal sources need to be monitored through a common communication interface.

These ratings describe the specified isolation barriers; they should not be interpreted as allowable continuous operating voltages or as a guarantee of protection against every surge or transient.

4. Standard RS485 Modbus RTU Communication

The 24DI series uses RS485 communication with the Modbus RTU protocol, making it suitable for integration with compatible PLCs, industrial controllers, computers, and automation software.

Supported communication settings include:

• Baud rates from 1,200 to 115,200 bps

• None, even, and odd parity

• Modbus RTU function codes 02, 03, 06, and 16

Using a standard industrial communication protocol makes it easier to integrate the module into existing systems, provided that the host software and selected Modbus operations are compatible.

RS485 also allows digital signals to be collected remotely over a serial communication bus, reducing the need to route every individual field signal directly to a central controller.

5. A Practical Choice for Remote Signal Monitoring

The 24DI series is designed for applications where the primary requirement is to read and monitor digital signals rather than directly switch loads.

Typical applications include:

Industrial automation

Monitor machine status, limit switches, sensor states, and equipment fault signals.

PLC input expansion

Add more digital input channels to compatible PLC-based systems through RS485 communication.

Building automation

Collect door contacts, switch states, equipment status, and other digital signals from multiple locations.

Security and access systems

Monitor compatible door contacts, alarm signals, and status outputs from security equipment.

CCTV and equipment monitoring

Collect compatible digital status signals from cameras, control equipment, and other connected devices.

Remote data acquisition

Gather multiple on/off signals for centralized monitoring, logging, or supervisory software.

For all these applications, the module provides a way to consolidate digital inputs without requiring a separate communication connection for every signal.

6. Flexible Power Supply and Enclosure Options

The modules operate from a DC supply within the published 6.5–25 V range, allowing use with compatible 9 V, 12 V, and 24 V power systems.

A protective enclosure option is available for installations that require a more organized and protected assembly inside a control cabinet.

The approximate dimensions are:

Model	Digital inputs	Board dimensions	Enclosed dimensions
24DIA16	16	68 × 72 × 25 mm	70 × 88 × 47 mm
24DIB32	32	120 × 72 × 25 mm	122 × 88 × 47 mm
24DIC48	48	167 × 72 × 25 mm	169 × 88 × 47 mm

The different sizes allow system designers to choose between a smaller installation footprint and a higher number of input channels.

7. How to Choose the Right Model

Selecting the right model depends primarily on the number of signals you need to monitor and the required input configuration.

• Choose the 24DIA16 for smaller systems requiring up to 16 digital input channels.

• Choose the 24DIB32 for medium-sized systems requiring up to 32 input channels.

• Choose the 24DIC48 for applications requiring up to 48 digital input channels in a single module.

Before purchasing, confirm the model's NPN/PNP input configuration, signal voltage, wiring requirements, and compatibility with your Modbus master or PLC.

8. Why Choose the Eletechsup 24DI Series?

The Eletechsup 24DIA16, 24DIB32, and 24DIC48 provide a straightforward solution for high-density digital input acquisition.

Key advantages include:

• 16, 32, or 48 digital input channels

• NPN/PNP input configurations available across the series

• Optical isolation for digital inputs

• Isolated RS485 communication interface

• Standard Modbus RTU protocol

• Configurable serial communication parameters

• Support for compatible 3.3 V, 5 V, 12 V, and 24 V digital signals

• Optional protective enclosure

For engineers, system integrators, and automation developers, the series offers a practical way to expand digital input capacity while simplifying signal collection and integration with compatible control systems.

Explore the Eletechsup 24DI Series

Need to monitor more digital signals without adding numerous separate input boards?

The Eletechsup 24DIA16, 24DIB32, and 24DIC48 offer three channel-count options for industrial signal acquisition, PLC input expansion, and RS485-based monitoring systems.

Visit the official product page to compare the available models and select the input configuration that fits your application.

Official product page: https://eletechsup.com/products/24dia16-24dib32-24dic48-16-32-48ch-di-npn-pnp-digital-switch-plc-io-expansion-3000vdc-optical

Note: Input configuration may differ by model or version. Always refer to the applicable product documentation for wiring, voltage limits, isolation specifications, and supported Modbus functions.