Waveshare Industrial Modbus RTU 8-Channel Relay Module (D) Instruction Manual

1. Producte acabatview

The Waveshare Industrial Modbus RTU 8-Channel Relay Module (D) is a robust and versatile device designed for industrial control and automation applications. It features 8 relay outputs and 8 digital inputs, communicating via the RS485 bus using the Modbus RTU protocol. This module incorporates multiple isolation protection circuits, including power isolation, magnetic isolation, and TVS diode protection, ensuring stable, reliable, and safe operation. Its rail-mounted ABS plastic enclosure facilitates easy installation in various industrial environments.

Figure 1: Waveshare Industrial Modbus RTU 8-Channel Relay Module (D)

1.1. Vídeo del producteview

Video 1: Modbus RTU Relay Series Overview. This video provides a general introduction to the Waveshare Modbus RTU relay series, highlighting key features and different versions available.

2. Contingut del paquet

Si us plau, verifiqueu que tots els elements que s'enumeren a continuació estiguin inclosos al vostre paquet:

• Modbus RTU Relay (D) x1
• Tornavís x1

Figura 2: Contingut del paquet

3. Característiques i especificacions

The Modbus RTU 8-Channel Relay Module (D) offers a comprehensive set of features for reliable industrial control:

• Configurable device address (1~255), allowing multiple devices to be cascaded on the RS485 bus.
• Features flash-on, flash-off function, enabling temporary relay activation with automatic closure.
• Onboard unibody power supply isolation provides stable isolated voltage, eliminating the need for an extra power supply for the isolated terminal.
• Onboard unibody magnetic isolation ensures signal isolation, high reliability, strong anti-interference, and low power consumption.
• Onboard resettable fuse and TVS (Transient Voltage Suppressor) effectively suppress surge voltage i transient spike voltage, providing over-current/over-voltage protection, lightning protection, and anti-electrostatic capabilities.
• Onboard Optocoupler isolation prevents interference from high-voltage circuits.
• Adopts a dedicated relay driver chip with built-in flyback diode protection for stronger and more stable driving ability.
• Supports passive and active digital input with bi-directional optocoupler isolation and built-in debouncing algorithm. The relay supports digital input linkage control or toggle control.
• Reverse-proof circuit prevents accidental damage from incorrect power connection.
• High quality relay with contact rating: ≤10A 250VAC/30VDC.
• Rail-mounted ABS plastic enclosure for easy installation and safe use.
• Multiple LEDs for indicating MCU status and signal transceiving status.

Figure 3: RS485 8-Channel Relay Module (D) with key features highlighted.

3.1. Especificacions tècniques

Figure 4: Detailed specifications and primary function diagram.

4. Maquinari acabatview i Protecció

The module is designed with multiple protection mechanisms to ensure safe and reliable operation:

• Aïllament de la font d'alimentació: Provides stable isolated voltage, eliminating the need for an external power supply for the isolated terminal.
• Magnetic Coupling Isolation: Ensures signal isolation, high reliability, strong anti-interference, and low power consumption.
• Optocoupler Isolation: Prevents interference from high-voltage circuits.
• TVS Lightning & ESD Protection: Effectively suppresses surge voltage i transient spike voltage.
• Fusible reiniciable: Provides over-current/over-voltagprotecció.
• Dedicated Relay Driver Chip: With built-in flyback diode protection for stronger and more stable driving.
• Reverse-Proof Circuit: Prevents accidental damage from incorrect power connection.

Figure 5: Internal hardware components and protection circuits.

5. Digital Input Functionality

The module supports both passive (dry contact) and active (wet contact) digital inputs, with bi-directional optocoupler isolation and a built-in debouncing algorithm. This allows for flexible integration with various sensors and switches.

• Passive Digital Input (Dry Contact): Connects to devices like button switches (self-reset) or ON/OFF switches (status hold).
• Active Digital Input (Wet Contact): Connects to devices like NPN proximity sensors or IR curtain sensors.

Figure 6: Digital input types and connection diagrams.

6. Interfaces and Indicators

The module features multiple LED indicators to monitor its operating status and communication activity:

• STA LED: MCU indicator, flashes when the MCU is operating normally.
• TXD LED: TX indicator, lights up when sending data.
• RXD LED: RX indicator, lights up when receiving data.
• Relay Working Indicators: Individual LEDs for each relay channel indicate its current state (ON/OFF).

Figure 7: Module interfaces and LED indicators.

7. Modes de funcionament

The module supports multiple relay control modes for various automation scenarios, with each channel supporting independent control settings:

• Normal Mode (Command Direct Control): Relays are controlled directly by sending Modbus commands.
• Flash ON / Flash OFF: Allows turning the relay ON for a specified duration and then automatically turning it OFF (Flash ON), or turning it OFF for a duration and then automatically turning it ON (Flash OFF). The duration is set by passing an argument to the command.
• Linkage Control: The output status of a relay follows the digital input status, enabling direct control based on sensor readings or switch states.
• Commuta el mode: When a pulse is input, the output status of the relay will toggle once (ON to OFF, or OFF to ON).

8. Comunicació RS485

The module communicates via the RS485 interface using the Modbus RTU protocol. It supports configurable device addresses (1-255), allowing multiple modules to be cascaded on a single RS485 bus. For long communication distances or a large number of cascaded devices, RS485 repeaters may be necessary to maintain signal integrity and system efficiency.

Figure 8: RS485 communication setup with multiple cascaded devices.

9. Relay Connection

The onboard relays have a contact rating of ≤10A 250VAC/30VDC, allowing direct control of various devices. Ensure proper wiring according to the load type:

• AC 220V Device Connection: Connect the AC load to the COM and NO (Normally Open) terminals of the relay.
• DC 30V Device Connection: Connect the DC load to the COM and NO (Normally Open) terminals of the relay.

Always ensure the power supply to the module is within the 7~36V range.

10. Enclosure and Installation

The module is housed in a rail-mounted ABS plastic enclosure, designed for easy installation and secure mounting on standard DIN rails. This design simplifies integration into industrial control cabinets and systems, providing both convenience and safety.

11. Aplicacions

The Waveshare Modbus RTU Relay series products are suitable for a wide range of applications requiring intelligent and automated control:

• Control Industrial: Valve control, pump station control, unattended industrial control systems.
• Casa intel·ligent: Controlling appliances like air conditioners, access control, purifiers, water heaters, etc.
• Agricultura intel·ligent: Controlling door curtain motors, air blowers, and other agricultural equipment.
• Breeding & Farming: Controlling ventilators, lighting, water supply, feeding systems, etc.

12. Cotes del contorn

The physical dimensions of the module are provided below for planning and integration purposes. All units are in millimeters (mm).

Figure 9: Outline dimensions of the Modbus RTU Relay (D) module.

13. Solució De Problemes

If you encounter issues with your Waveshare Industrial Modbus RTU 8-Channel Relay Module (D), please consider the following common troubleshooting steps:

• Sense alimentació/Indicadors apagats: Comproveu la connexió de la font d'alimentació i assegureu-vos que el volumtage is within the 7~36V range. Verify the power adapter is functioning correctly.
• Falla de comunicació: Ensure the RS485 A+, B-, and GND connections are correct and secure. Check the baudrate, parity, data bits, and stop bits settings on your Modbus master device match the module's default or configured settings. Verify the device address is unique and correctly set.
• El relé no s'activa: Confirm that the Modbus commands sent are correct for the desired relay action (ON/OFF, Flash, Linkage, Toggle). Check the load connected to the relay is within the specified contact rating (≤10A 250VAC/30VDC).
• Digital Input Not Responding: Ensure the digital input connections are correct for either passive (dry contact) or active (wet contact) input. Verify the external switch or sensor is functioning properly.
• Funcionament intermitent: Check for loose connections or environmental interference. Ensure proper grounding.

For persistent issues, refer to the detailed product documentation available on the Waveshare website or contact Waveshare technical support.

14. Garantia i Suport

Waveshare products typically come with a standard manufacturer's warranty. For specific warranty terms and conditions, please refer to the warranty information provided with your purchase or visit the official Waveshare website. Technical support is available through the Waveshare support channels, including online documentation, forums, and direct contact options. Please have your product model and purchase details ready when seeking support.

For the latest drivers, software, and detailed technical resources, please visit the Waveshare official weblloc: www.waveshare.com