MODBUS RTU 7-24V 1-Channel Relay Module RS485/TTL

MODBUS RTU 7-24V 1-Channel Relay Module RS485/TTL is a versatile and industrially hardened switching solution designed for seamless integration into automated control systems. This module features a high-quality onboard relay capable of handling significant AC and DC loads while communicating via the standard Modbus RTU protocol. Furthermore, it supports both RS485 and TTL UART interfaces, providing engineers with the flexibility to connect directly to PLCs, industrial computers, or low-voltage microcontrollers. Users can easily daisy-chain multiple modules on a single RS485 bus thanks to the programmable device addressing. Consequently, this module serves as an ideal bridge between digital command logic and high-power electrical hardware in demanding environments. Therefore, you can achieve reliable remote load management with minimal wiring complexity using this compact and robust controller.

Key Features:

• Dual Communication Interfaces: The module integrates both RS485 and TTL level UART interfaces, allowing for long-distance industrial communication or short-range logic level interfacing.
• Standard Modbus RTU Protocol: It supports standard function codes for reading coil status and writing single/multiple coils, ensuring compatibility with most SCADA software and PLC systems.
• Wide Input Voltage Range: The onboard power regulation accepts a broad supply range from 7V to 24V DC, making it compatible with various industrial power rails.
• Configurable Baud Rate: Users can modify communication parameters, such as baud rate and parity, to match existing network requirements.
• Onboard Protection: Features diode freewheeling protection and optocoupler isolation to safeguard the control circuitry from inductive kickback and electrical noise.

Technical Specifications:

• Operating Voltage: 7V to 24V DC
• Communication Protocol: Modbus RTU
• Baud Rate Options: 4800, 9600, 19200, 38400 (Default is typically 9600 bps)
• Relay Contact Rating (AC): 10A at 250V AC
• Relay Contact Rating (DC): 10A at 30V DC
• Response Time: ≤ 10ms
• Isolation: Optocoupler isolated input circuitry

Mechanical Specifications:

• Mounting Type: PCB with mounting holes for chassis installation
• Terminal Blocks: Screw-type terminals for secure wire connections
• Indicator LEDs: Onboard LEDs for Power (PWR) and Relay Status (Relay On/Off)
• Construction: High-grade FR-4 PCB with tinned traces for high current paths

Dimensions:

• Board Length: ≈ 45 mm
• Board Width: ≈ 30 mm
• Overall Height: ≈ 18 mm
• Weight: ≈ 25 g

Pinout and Wiring:

• VCC / GND: Power supply input (7-24V DC).
• A+ / B-: RS485 communication differential pair for industrial bus networking.
• TXD / RXD: TTL UART pins for direct connection to 5V microcontrollers.
• COM: Common terminal of the relay switch.
• NO: Normally Open contact; closes when the relay is energized via Modbus command.
• NC: Normally Closed contact; opens when the relay is energized.

Datasheet Reference:

• Download Modbus RTU Relay Module User Guide and Protocol Reference

Commonly Used in:

• PLC Expansion: Adding extra relay outputs to existing Programmable Logic Controllers via the RS485 port.
• Smart Building Systems: Controlling lighting, HVAC, and access points through centralized Modbus gateways.
• Energy Management: Remote switching of electrical circuits to optimize power consumption in commercial facilities.

Applications:

• Industrial Automation: Executing remote start/stop commands for machinery and motors in factory settings.
• Agricultural Monitoring: Automating irrigation pumps and greenhouse ventilation systems based on sensor data.
• Computer-Controlled Switching: However, it is also highly effective for DIY home server projects using a USB-to-RS485 adapter for PC-based control.

Equivalent Models:

• Waveshare Modbus RTU Relay: A functionally identical industrial module often used in professional deployments.
• XY-MR01 Relay Module: A similar single-channel Modbus RTU controller with a smaller footprint.
• LC-Modbus-Relay-1: A common alternative board sharing the same register map and 7-24V input range.

Package Includes:

• 1 x MODBUS RTU 7-24V 1-Channel Relay Module (RS485/TTL)