N4AIA04: 4-Channel Analog Input Acquisition Module with RS485 Modbus RTU

 N4AIA04 is a compact four-channel analog signal acquisition module designed to measure voltage and current signals and transfer the measurement data to a host controller through an RS485 interface.

Supporting the Modbus RTU communication protocol, the N4AIA04 is suitable for industrial automation, sensor monitoring, PLC integration, embedded systems, and remote data acquisition applications.

One of its key advantages is its combination of two voltage measurement channels and two current measurement channels on a single compact board. This allows engineers to monitor different types of analog sensors without using separate acquisition modules for each signal type.

According to the manufacturer's published specifications, the module operates from a DC 8–25 V supply and supports Modbus RTU function codes 03 and 06. Its compact dimensions make it suitable for space-constrained control panels and embedded monitoring projects.

2. Key Features

  • Four analog input channels: Two voltage inputs and two current inputs.

  • Multiple voltage ranges: One channel supports 0–5 V, while another supports 0–10 V.

  • Industrial current signal acquisition: Two channels support 0–20 mA and 4–20 mA sensor signals.

  • RS485 communication: Enables remote acquisition and communication over a shared serial bus.

  • Modbus RTU protocol: Compatible with suitable PLCs, PCs, embedded controllers, and Modbus master software.

  • High-resolution measurement: Voltage resolution of 0.01 V and current resolution of 0.1 mA.

  • Measurement accuracy: Manufacturer specifies approximately 1% accuracy, with calibration available if required.

  • Flexible power supply: DC 8–25 V operating range.

  • Compact size: Approximately 45 × 30 × 15 mm.

  • Multi-device networking: The manufacturer specifies support for up to 247 devices in Modbus command mode, subject to addressing and network requirements.

3. Technical Specifications

Parameter Specification
Model N4AIA04
Number of channels 4 analog inputs
Channel V1 0–5 V voltage measurement
Channel V2 0–10 V voltage measurement
Channels C1 and C2 0–20 mA / 4–20 mA current measurement
Operating voltage DC 8–25 V
Operating current Approximately 10–14 mA
Voltage resolution 0.01 V
Current resolution 0.1 mA
Measurement accuracy Approximately 1%, according to manufacturer
Communication interface RS485
Communication protocol Modbus RTU
Supported function codes 03 and 06
Dimensions Approximately 45 × 30 × 15 mm
Weight Approximately 10 g

Specifications are based on the manufacturer's published product listing. Refer to the applicable manual for register addresses, communication parameters, wiring details, and calibration procedures.

4. How the N4AIA04 Works

The N4AIA04 measures analog voltage and current signals from external devices, converts them into digital measurement data, and makes that data available to a Modbus RTU master through RS485.

A typical system consists of the following components:

  1. Analog sensors or transmitters.

  2. The Eletechsup N4AIA04 acquisition module.

  3. An RS485-to-USB adapter, PLC, or embedded controller.

  4. Host software for reading, displaying, recording, or processing measurements.

For example, an industrial monitoring system could use the module to collect a 0–5 V sensor output, a 0–10 V control signal, and two 4–20 mA transmitter signals.

The host controller can then retrieve the measurements periodically and use them for monitoring, alarms, data logging, or further automation.

5. GitHub Integration and Software Examples

The N4AIA04 is documented in public GitHub projects, providing useful references for developers who want to integrate the module into software-based monitoring systems.

GitHub Project 1: Modbus RTU Integration for Home Assistant

Repository: arturmietek/ha-modbus-manager

This project provides a Modbus integration for Home Assistant, including YAML-based device definitions. Its documented device library includes an N4AIA04 definition.

The project demonstrates a possible approach to integrating the module into a home or industrial monitoring dashboard.

Potential applications include:

  • Displaying analog sensor readings in Home Assistant.

  • Monitoring current-loop transmitters.

  • Tracking voltage signals from compatible equipment.

  • Building dashboards and automated alerts.

  • Combining analog measurements with other Modbus devices.

The integration requires correct bus settings, the appropriate device definition, and matching register addresses and data scaling.

GitHub Project 2: Python-Based Modbus RTU Control

Repository: ul-gh/cheap_modbus_rtu

This Python library documents support for the Eletechsup N4AIA04 analog input module. It offers a software-oriented starting point for engineers developing their own data acquisition applications.

A typical Python implementation would follow this general workflow:

from pymodbus.client import ModbusSerialClient

client = ModbusSerialClient(
    port="/dev/ttyUSB0",
    baudrate=9600,
    parity="N",
    stopbits=1,
    bytesize=8,
    timeout=1
)

if client.connect():
    # Read holding registers using the
    # correct address and quantity from
    # the N4AIA04 register documentation.
    response = client.read_holding_registers(
        address=0,
        count=1,
        device_id=1
    )

    if not response.isError():
        print(response.registers)

    client.close()

Important: This is a generic Modbus RTU example, not a verified, ready-to-run N4AIA04 register-reading script. The slave ID, baud rate, register address, register quantity, and data conversion must match the actual module configuration and its protocol documentation. Check the installed PyModbus version because parameter names can differ between releases.

Once configured correctly, a Python application can periodically acquire the measurements and forward them to a database, dashboard, or another control system.

6. Practical Applications

Industrial Automation and PLC Systems

The N4AIA04 can collect voltage and current signals from compatible industrial transmitters and provide measurement data to a PLC or supervisory controller. Its mixed-input design can simplify small automation projects that require both voltage and current measurement.

Pressure, Flow, and Level Monitoring

Many industrial pressure, flow, and liquid-level transmitters provide a 4–20 mA output. The N4AIA04's current input channels can acquire compatible transmitter signals for monitoring and data logging.

The engineering software must convert the measured current into the corresponding physical quantity using the sensor's calibration range.

For example, a 4–20 mA pressure transmitter can be scaled from its 4 mA minimum to its 20 mA maximum according to the transmitter's rated pressure range.

Voltage Sensor Monitoring

The 0–5 V and 0–10 V inputs are suitable for compatible analog sensors, voltage-output transmitters, and control signals within their specified measurement ranges.

Engineers should verify the output range and electrical compatibility of each connected device before wiring it to the module.

Smart Home and Building Automation

With a suitable RS485 master and software integration, the N4AIA04 can be used to monitor compatible analog sensors in building management and home automation systems.

Embedded Systems and Remote Data Acquisition

The RS485 interface makes the module suitable for integration with computers, industrial gateways, and embedded controllers. Developers can use Modbus-compatible software to retrieve measurements and build customized monitoring applications.

7. Why Choose Eletechsup N4AIA04?

The N4AIA04 offers a practical combination of four analog inputs, mixed voltage and current measurement, RS485 communication, and Modbus RTU compatibility.

Its main advantages include:

  • Mixed-signal capability: Two voltage inputs and two current inputs on one board.

  • Simple system integration: Standard Modbus RTU communication for compatible industrial controllers.

  • Compact hardware: Suitable for embedded applications and small control cabinets.

  • Software development options: Public GitHub references for Python-based Modbus projects and Home Assistant integration.

  • Cost-conscious design: A compact alternative for projects that do not require a large industrial analog I/O system.

Before selecting the module, engineers should confirm input ranges, measurement accuracy, electrical isolation requirements, register mapping, and compatibility with their chosen Modbus master.

Conclusion

The Eletechsup N4AIA04 is a compact four-channel analog acquisition module designed for voltage and current measurement in industrial automation, sensor monitoring, and embedded data acquisition applications.

Its combination of 0–5 V, 0–10 V, and 0–20 mA / 4–20 mA input capabilities makes it useful for projects involving different types of analog sensors. RS485 and Modbus RTU support provide a straightforward path to integration with PLCs, computers, and compatible monitoring software.

Public GitHub projects further demonstrate how the N4AIA04 can be incorporated into Python-based applications and Home Assistant monitoring systems, helping developers move from hardware acquisition to practical software integration.

Official product page: https://eletechsup.com/products/n4aia04-dc-12v-4-20ma-0-5v-0-10v-voltage-signal-acquisition-rs485-modbus-rtu-module

GitHub — Home Assistant Modbus integration: https://github.com/arturmietek/ha-modbus-manager

GitHub — Python Modbus RTU library: https://github.com/ul-gh/cheap_modbus_rtu

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