Waveshare Industrial Modbus RTU Analog Input 8CH Module

1. Introduction

The Waveshare Industrial Modbus RTU Analog Input 8CH module is a high-precision industrial-grade data acquisition device designed for robust and reliable performance in various industrial environments. It supports 8 channels of simultaneous analog input, capable of acquiring both voltage and current signals with 12-bit resolution. Utilizing the standard Modbus RTU protocol over an RS485 interface, this module offers wide compatibility with industrial control systems such as PLCs and host computers.

Key features include a wide DC 7~36V power supply range, multiple isolation protections (power, magnetic, resettable fuse, TVS), and configurable input ranges, making it a versatile solution for precise analog data monitoring.

2. Features At A Glance

• High-Precision Acquisition: 12-bit resolution with an accuracy of ≤3% for precise data.
• Multi-Channel Input: 8-channel simultaneous analog acquisition.
• Flexible Input Modes: Supports single-ended/differential input and simultaneous voltage and current acquisition.
• Configurable Ranges: Multiple voltage and current ranges configurable via software (e.g., 0-5V, 1-5V, 0-10V, 2-10V, 0-20mA, 4-20mA).
• Modbus RTU Protocol: Standard protocol for wide compatibility with industrial systems.
• RS485 Interface: Allows cascading of multiple devices with configurable addresses (1~255).
• Wide Voltage Power Supply: Operates on DC 7~36V.
• Industrial-Grade Isolation: Onboard unibody power supply isolation and magnetic isolation for signal integrity and strong anti-interference.
• Robust Protection: Features resettable fuse, TVS (Transient Voltage Suppressor) for surge, over-current/over-voltage, lightningproof, and ESD protection.
• Stable Operation: Built-in oversampling digital filtering algorithm and watchdog for stable output without crashing.
• Easy Installation: Rail-mount case design (35mm standard guide rail) and support for stacking combination.
• Status Indicators: Three LEDs (RXD, TXD, STATUS) for monitoring MCU and communication status.

3. Specifications

4. Package Contents

The package contents vary slightly depending on the version purchased:

Modbus RTU Analog Input 8CH (Standard Version)

• Modbus RTU Analog Input 8CH x1
• Power supply terminal adapter x1

Modbus RTU Analog Input 8CH (B) (B Version)

• Modbus RTU Analog Input 8CH (B) x1
• Power supply terminal adapter x1
• Jumper cap 10PCS x1

Note: The power supply for this product is not included. A 12V power supply is recommended if needed.

5. Setup and Installation

5.1 Interface Overview

Familiarize yourself with the module's interfaces:

5.2 Power Supply Connection

Connect a DC 7~36V power supply to the 7-36V and GND terminals. Ensure correct polarity. The module features anti-reverse protection, ESD protection, and power supply/signal dual isolation for enhanced safety and reliability.

5.3 RS485 Communication Connection

Connect the RS485 A+ and B- terminals to your host device (PC or PLC). Multiple modules can be cascaded on the RS485 bus by setting unique device addresses (1~255) for each module.

5.4 Analog Input Configuration

The module supports both voltage and current acquisition. The input mode (voltage or current) is switchable via jumpers. Specific ranges are configurable via software.

• Modbus RTU Analog Input 8CH (Standard): Supports 0~5V/1~5V and 0~20mA (default)/4~20mA.
• Modbus RTU Analog Input 8CH (B): Supports 0~10V (default)/2~10V and 0~20mA/4~20mA.

Refer to the detailed wiring and jumper settings in the diagram below for configuring voltage or current acquisition and selecting the appropriate range.

5.5 Physical Installation (Rail-Mount)

The module is designed for 35mm standard guide rail mounting. It comes with a rail-mount buckle for easy installation. For stacking multiple modules, remove the rail-mount buckle from the outer module, then assemble the modules together using screws.

6. Operating Instructions

6.1 Primary Function

The module's primary function is to acquire analog data from 0~20mA or 0~10V sensors and transmit it to a host device (PC or PLC) using Modbus RTU protocol commands via the RS485 interface.

6.2 Modbus RTU Communication

The module operates as a Modbus RTU slave device. Your host system (master) will send Modbus commands to read the analog input registers. The default communication format is 9600, N, 8, 1 (Baud Rate, Parity, Data Bits, Stop Bits). The device address is configurable from 1 to 255.

For detailed Modbus register maps and command structures, please refer to the product's Wiki page mentioned in the 'Warranty & Support' section.

6.3 LED Indicators

• RXD LED: Indicates data reception activity on the RS485 interface.
• TXD LED: Indicates data transmission activity on the RS485 interface.
• STATUS LED: Indicates the MCU's working status. Refer to the Wiki for specific status codes or patterns.

7. Maintenance

• Cleaning: Keep the module clean and free from dust and debris. Use a soft, dry cloth for cleaning. Avoid using liquids or abrasive cleaners.
• Environmental Conditions: Ensure the module operates within its specified temperature and humidity ranges to prevent damage.
• Firmware Updates: Check the Waveshare Wiki periodically for any available firmware updates that may improve performance or add features. Follow the instructions provided for safe updating.
• Connection Integrity: Regularly inspect all wiring connections (power, RS485, analog inputs) to ensure they are secure and free from corrosion or damage.

8. Troubleshooting

• No Power/Module Not Responding:
  • Verify the DC 7~36V power supply is correctly connected and providing the specified voltage.
  • Check the power supply terminal adapter for proper connection.
  • Ensure the power supply itself is functional.
• No Communication via RS485:
  • Confirm RS485 A+ and B- connections are correct.
  • Check the baud rate, parity, data bits, and stop bits settings on both the module (default 9600, N, 8, 1) and the host device.
  • Verify the module's device address is unique and matches the address used by the host.
  • Ensure the RS485 bus is properly terminated if necessary (refer to RS485 best practices).
  • Check the RXD/TXD LEDs for activity. If no activity, check wiring and host communication settings.
• Inaccurate Analog Readings:
  • Confirm the correct input mode (voltage/current) is selected via jumpers.
  • Verify the software-configured range matches the sensor's output range.
  • Ensure the sensor is correctly wired to the AIx+ and AIx- terminals.
  • Check for external electrical noise or interference in the environment.
  • Ensure the sensor itself is calibrated and functioning correctly.
• Module Crashing/Unstable:
  • While the module has a built-in watchdog, ensure the power supply is stable and within the specified voltage range.
  • Check for excessive heat if operating in a confined space.

9. User Tips

• Software Configuration: Always refer to the official Waveshare Wiki for the latest software tools and detailed instructions on configuring input ranges and device addresses.
• Wiring Best Practices: For industrial environments, use shielded cables for analog inputs and RS485 communication to minimize interference. Ensure proper grounding.
• Testing: Before deploying in a critical application, thoroughly test the module with known voltage/current sources across all desired ranges to verify accuracy and stability.
• Documentation: Keep a record of your module's configuration (device address, baud rate, input ranges) for easier troubleshooting and maintenance.

10. Warranty & Support

For detailed technical documentation, programming guides, software tools, and further support, please visit the official Waveshare Wiki:

www.waveshare.com/wiki/Modbus_RTU_Analog_Input_8CH

Waveshare provides comprehensive resources to assist users with their products. Please refer to the Wiki for the most up-to-date information and troubleshooting guides.