MODBUS RTU 7-24V 2-Channel Relay Module RS485/TTL

MODBUS RTU 7-24V 2-Channel Relay Module RS485/TTL is a professional-grade industrial control board designed for remote switching applications over long distances using the robust Modbus RTU protocol. This module integrates two independent high-quality relays capable of handling significant AC and DC loads, while offering dual communication interfaces via RS485 and TTL UART. Consequently, users can easily interface this device with PLCs, industrial computers, or low-voltage microcontrollers like Arduino and ESP32. Furthermore, the wide input voltage range ensures compatibility with standard 12V and 24V industrial power rails. Therefore, you can implement reliable, addressable hardware control in complex automation environments with minimal wiring complexity.

Key Features:

• Standard Modbus RTU Protocol: Supports industry-standard function codes for reading coil status and writing multiple or single coils, ensuring seamless integration with existing SCADA systems.
• Dual Communication Interface: Features both an RS485 port for long-range differential signaling and a TTL UART port for direct connection to local logic-level controllers.
• Addressable Control: Allows for daisy-chaining multiple modules on a single bus by configuring unique device addresses from 1 to 255.
• Flash-Off and Flash-On Functionality: Includes specialized Modbus commands to trigger relays for a set duration, which is highly useful for momentary pulse applications.
• Onboard Protection: Incorporates diode anti-surge protection and optocoupler isolation to safeguard the control circuitry from high-voltage transients.

Technical Specifications:

• Operating Voltage: DC 7 V to 24 V
• Communication Protocol: Modbus RTU (Baud rate options: 4800, 9600, 19200 bps; Default: 9600)
• Relay Load Capacity: AC 250 V / 10 A or DC 30 V / 10 A
• Input Current: ≥ 100 mA (With both relays engaged)
• Isolation: Optocoupler isolation between signal and power stages
• Status Indicators: Onboard LEDs for Power (PWR), Relay 1 (D1), and Relay 2 (D2) status.

Mechanical Specifications:

• Mounting Type: Standard PCB mounting holes for secure enclosure installation.
• Terminal Blocks: High-quality screw terminals for robust electrical connections.
• PCB Material: FR-4 high-density fiberglass board with a protective solder mask.
• Interface Protection: RS485 circuit includes TVS surge protection.

Dimensions:

• Board Length: ≈ 75 mm
• Board Width: ≈ 42 mm
• Height: ≈ 20 mm
• Mounting Hole Diameter: 3 mm
• Net Weight: ≈ 55 g

Pinout and Wiring:

• VCC / GND: Power input terminals (7-24 V DC).
• 485A / 485B: RS485 differential signal pair for bus communication.
• RXD / TXD: TTL UART pins for 3.3V/5V logic level communication.
• COM / NO / NC: Common, Normally Open, and Normally Closed terminals for each relay channel.
• Wiring Note: However, always ensure that the RS485 bus is terminated with a 120 Ω resistor at the furthest node to prevent signal reflections over long cables.

Datasheet Reference:

• Download Modbus RTU 2-Channel Relay Module Datasheet

Commonly Used in:

• Industrial Automation: Controlling pumps, valves, and heaters through a central PLC or computer.
• Smart Building Systems: Managing lighting and HVAC zones via RS485 building management networks.
• Remote Monitoring Stations: Enabling remote power cycling of equipment in solar-powered or remote telecommunication sites.

Applications:

• PLC Expansion: Adding additional relay outputs to existing PLCs that support Modbus RTU.
• Data Center Management: Remotely rebooting servers or networking hardware through a management console.
• Agricultural Automation: Managing irrigation cycles and climate control systems in large greenhouses.

Equivalent Models:

• LC-Modbus-Relay-2: The standard LCTECH variation often used as the primary reference design.
• Waveshare Modbus RTU Relay: A functionally identical model nonetheless featuring a DIN-rail mountable enclosure for professional cabinet installation.
• XY-IO88: A higher-density Modbus relay board that provides similar logic control over RS485.

Package Includes:

• 1 x MODBUS RTU 7-24V 2-Channel Relay Module RS485/TTL