Modbus RTU RS485 Relay Module 3/4/6/8‑Channel High‑Power 30A Output TTL Communication Control Board For PLC Industrial Automation Switch

Modbus RTU RS485 Relay Control Module 3/4/6/8‑Channel High‑Power Relay Board

📌 Product Overview

This Modbus RTU‑485 relay control module supports standard Modbus RTU communication protocol, equipped with dual communication interfaces of RS485 and TTL. Multiple specifications are optional: 3‑channel, 4‑channel, 6‑channel and 8‑channel versions. It adopts high‑power Hongfa relay with NO/NC contact output, compatible with PLC, industrial touch screen and upper computer software control. Part of the models carry switch quantity detection input terminals, which can read external switch status through the 485 bus. It features reliable industrial‑grade design, widely used in industrial automation, smart home control, equipment power switching and remote switching control projects.

✨ Core Features

1. Standard Modbus RTU communication protocol, easy for secondary development
2. Dual communication ports: RS485 and TTL for flexible connection
3. Optional 3‑channel / 4‑channel / 6‑channel / 8‑channel high‑power Hongfa relays
4. Each relay supports Normally Open (NO) and Normally Closed (NC) output
5. Independent working indicator for each relay to display real‑time status
6. Partial versions reserve multi‑channel digital input for external switch signal acquisition
7. Separate power indicator and program running indicator
8. Dual power supply terminals: round DC‑2.5 socket and 5.08mm green terminal block
9. Reserved program download port for function modification and firmware upgrade
10. Support host computer, PLC, touch screen centralized remote control
11. Compact industrial PCB layout, convenient for cabinet installation

📋 Product Specifications

Item	Parameter
Communication Protocol	Modbus RTU
Communication Interface	RS485 + TTL
Optional Channel	3‑CH / 4‑CH / 6‑CH / 8‑CH
Relay Brand	HONGFA high‑power relay
Relay Contact	NO / NC switch output
Input Detection	4‑way switch input for 4‑CH model; reserved 8‑way for 6/8‑CH
Power Supply	DC 12V
Indicator	Relay working light, power light, program running light
Working Temperature	‑40℃ ~ +85℃

🔌 Terminal Definition

‑ Relay terminal: NO(Normally Open), NC(Normally Closed) for each channel ‑ Communication terminal: 485A, 485B ‑ TTL port: GND, VCC, 3.3V, IN1~INx switch input pins ‑ Power port: DC power input ‑ Download port: Firmware upgrade and parameter configuration

📑 Model Description

‑ 4‑channel model: ME40RM012‑44D1ST, with 4‑channel switch signal input ‑ 6‑channel model: ME40RM012‑68D1ST, reserved 8‑channel input, not welded by default ‑ 8‑channel model: ME40RM012‑88D1ST, reserved 8‑channel input, not welded by default

🛠 Wiring Instruction

‑ Load wiring: Connect the controlled load between NO/NC terminal and power line ‑ Communication wiring: 485A and 485B connect to upper computer or PLC bus ‑ Switch input: External dry‑contact switch connects to INx pin and GND for status reading ‑ Power supply: DC12V power supply access to the power terminal

🎯 Application Scenarios

‑ PLC expansion relay output module ‑ Industrial equipment remote switch control ‑ Smart cabinet power management ‑ Intelligent lighting centralized control system ‑ Automation production line power switching ‑ DIY industrial control and IoT remote control projects