Dual Ethernet 8-Channel Relay Module (C) - Modbus RTU/TCP, PoE, 8 Digital Inputs

Eight high-power relay channels and eight optically isolated digital inputs, driven over standard Modbus from anywhere on your network.

Industrial panels normally pay for that reach twice: a switch port for the data and a separate supply for the hardware. Two cascadable Ethernet ports change the arithmetic — chain one module to the next and carry both the traffic and the power along the chain, so a row of enclosures can run off a single drop instead of one run per device.

Isolation is built into both halves. The inputs sit behind bi-directional optocouplers with a debouncing algorithm, the relay side runs a dedicated driver chip with flyback protection, and a reverse-proof supply circuit tolerates a terminal block wired backwards. The whole lot ships in a DIN-rail ABS enclosure rated for -15°C to 70°C.

It speaks Modbus RTU or Modbus TCP over TCP, UDP or MQTT, and is configured either through Waveshare's VirCom utility or any web browser. Python demo code for the Raspberry Pi is published on the wiki. Note that a DC supply is not included - power the module over PoE, or add a 5.5 x 2.1mm DC adapter (7-36V).

Features

• Runs its own logic without a controller - each channel can be set to Normal, Linkage, Toggle or Edge Trigger, so an input can drive its relay directly even if the network drops
• Timed pulses without polling: flash-on and flash-off take an interval argument, energising a channel for a set period and releasing it automatically
• Accepts either dry-contact or wet-contact inputs (NPN or PNP), so existing field wiring rarely needs rework
• Switches 230V appliances directly thanks to 1NO 1NC contacts rated to 10A, with no intermediate contactor
• Tolerates unregulated panel supplies across a 7-36V range, alongside the DC jack and PoE options
• Integrates with cloud tooling out of the box — MQTT and HTTP GET/POST control are documented, with an Alibaba Cloud demo included
• Four status LEDs plus per-port link and activity indicators make a wiring or link fault visible at the rail rather than from a terminal

Specifications

Resources

• Waveshare wiki - setup, register map and full Modbus command reference