8-Ch ESP32-S3 WiFi Relay Module
4.8Editor score
Ethernet, Wi-Fi, and Bluetooth
Isolated RS485 interface
Eight relay and input channels
Integrated PoE networking
In this guide
An Ethernet relay module connects remotely controlled switches to a local network, making it useful for industrial equipment, smart buildings, agriculture, access systems, and home automation. A capable unit should offer dependable network communication, clear configuration options, adequate relay channels, and suitable electrical protection for the intended installation.
The products in this guide were compared using the supplied specifications, focusing on relay count, supported protocols, Ethernet and wireless connectivity, digital inputs, power options, isolation circuits, enclosure design, and development resources. The list includes both dedicated Modbus modules and more flexible ESP32-S3 models with RS485, Wi-Fi, Bluetooth, and programmable control.
Each review explains the strongest reasons to consider a particular module while identifying trade-offs that may affect a purchase. Ratings and product details reflect the supplied marketplace information, while pricing, availability, and configurations can change. Always verify the exact version, electrical ratings, documentation, and accessories before ordering equipment for a project.
Top 3 Picks for Best Ethernet Relay Module
8-CH Ethernet Relay Module (B)
4.9Editor score
Eight isolated digital inputs
Modbus and MQTT support
PoE plus wide DC input
Web and software configuration
Pinhaijing LAN Ethernet 2-Way Relay
4.8Editor score
Compact two-relay board
TCP and UDP control
Built-in web server
Password-protected remote access
Top 10 Best Ethernet Relay Module in 2026 Compared
The comparison below organizes the ten modules by channel count, control protocol, input options, power methods, and connectivity. It highlights the main differences between compact boards, Modbus-focused industrial units, and programmable ESP32-S3 systems.
ProductsSpecificationsEditor scorePrice
Best Budget
8-CH Modbus PoE Relay
Eight relay channels
Modbus RTU and TCP
PoE and wide DC input
Rail-mount ABS enclosure
3.4Editor score
Editor's Choice
Waveshare 8-CH Modbus Relay
Eight relay channels
Modbus RTU and TCP
MQTT remote control
Industrial rail enclosure
4.1Editor score
Best Premium
8-Ch ESP32-S3 PoE Relay
Eight relay channels
Wi-Fi and Bluetooth LE
Isolated RS485 interface
PoE Ethernet connectivity
4.8Editor score
8-CH Ethernet Relay Module (B)
Eight relay channels
Eight digital inputs
Modbus, HTTP, and MQTT
PoE and wide DC input
4.9Editor score
8-Ch ESP32-S3 Ethernet Relay
Eight relay channels
Eight digital inputs
Wi-Fi and Bluetooth LE
Isolated RS485 interface
4.6Editor score
Waveshare 30-CH Ethernet Relay
Thirty relay channels
Modbus RTU and TCP
PoE and wide DC input
Industrial rail enclosure
4.2Editor score
Waveshare ESP32-S3 PoE Relay
Eight relay channels
Isolated RS485 interface
Wi-Fi and Bluetooth LE
Wide DC voltage input
4.7Editor score
8-CH Ethernet Relay Module (B)
Eight relay channels
Eight digital inputs
Modbus and MQTT support
PoE and wide DC input
4.2Editor score
Pinhaijing LAN Ethernet Relay
Two relay channels
TCP and UDP control
Integrated web server
Compact FR-4 circuit board
4.8Editor score
8-CH Modbus PoE Relay
Eight relay channels
Modbus RTU and TCP
Multiple network modes
PoE and wide DC input
4.0Editor score
1. 8-CH Modbus PoE Relay – Versatile Network Switching
8-CH Modbus PoE Relay
Eight independently controlled relays
Modbus RTU and TCP
DC and PoE power options
Optocoupler and reverse protection
The 8-CH Ethernet Relay Module provides eight relay outputs, Ethernet control, Modbus RTU and Modbus TCP support, and a rail-mount ABS enclosure. Its supplied rating is 3.4, the lowest in this comparison, so buyers should not treat it as a universally proven favorite. The specification set is nevertheless focused and practical for users who need network-controlled switching without a large programmable controller.
Pros
- Eight channels in one enclosure
- Supports standard Modbus protocols
- Accepts broad DC input voltage
- Includes timed relay operation
- Works with MQTT platforms
Cons
- Lowest customer rating here
- Fewer documented input features
- No onboard RS485 stated
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Power flexibility is one of its most useful characteristics. It accepts DC 7-36V input and also supports PoE, while optocoupler isolation helps reduce interference between the relay side and control electronics. A reverse-proof circuit is also listed. The flash-on, flash-off function allows a relay to remain active for a specified interval and then switch off, which is useful for temporary outputs rather than simple on/off commands.
The trade-offs are that the supplied information does not highlight digital inputs, broad protocol modes, or an onboard RS485 interface. MQTT control and an Alibaba Cloud MQTT application demo are useful, but buyers with highly specific SCADA, BACnet, or custom hardware requirements may need documentation that is not summarized in the product details. The lower rating may also reflect customer experiences, installation issues, or version differences that cannot be determined from the specifications alone.
This module is a sensible candidate for Modbus-based control cabinets, equipment automation, and remotely managed relay tasks where eight outputs and PoE support matter more than wireless control or custom firmware. It is also appropriate for integrators already familiar with Modbus register mapping. For buyers prioritizing rich input support, many network modes, or a newer programmable platform, one of the more highly rated models may offer a clearer feature match.
Flexible Power and Network Operation
The combination of broad DC input and PoE gives installers more options for cabinet power. Ethernet control and MQTT support also provide a useful path from local programming to connected automation.
Useful Temporary Switching Behavior
The timed flash-on and flash-off feature makes the unit better suited to pumps, valves, warning devices, and other outputs that may only need to run for a defined period.
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2. Waveshare 8-CH Modbus Relay – Industrial Enclosure Choice
Waveshare 8-CH Modbus Relay
Eight standard relay outputs
Modbus RTU and TCP
PoE and DC power
Status and network indicators
This Waveshare 8-CH Ethernet Relay Module combines eight outputs with Modbus RTU and Modbus TCP operation, PoE capability, and an industrial-grade rail-mount case. Its supplied rating of 4.1 places it above the first module in the ranking without matching the strongest customer ratings. It is aimed particularly at control-panel users who value a protected enclosure and familiar industrial protocols.
Pros
- Rail-mounted industrial enclosure
- Multiple standard control protocols
- Isolation and reverse protection
- Clear status indicator layout
- MQTT and timed operation support
Cons
- No digital inputs specified
- Onboard RS485 not listed
- Programming details are limited
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The module accepts DC 7-36V input or PoE and supports relay control through MQTT, including an Alibaba Cloud MQTT application demo. Optocoupler isolation, reverse-proof circuitry, and relays rated up to 10A at 250VAC or 30VDC support its industrial positioning. Four LEDs and network indicators provide visible feedback for microcontroller status and signal transmission, which helps during commissioning and troubleshooting.
The primary limitation is that the supplied specification does not identify digital inputs or an RS485 interface. That makes it less versatile than several other eight-channel options when a project needs to read sensors, accept external trigger signals, or connect Modbus RTU devices locally. The MQTT demonstration may also be aimed at a particular ecosystem rather than a general cloud platform, so integrators should review its documentation before depending on it.
For users building fixed Modbus control systems, this is a well-aligned module with a practical enclosure and straightforward power options. It is especially attractive for equipment that needs scheduled outputs, MQTT integration, or a rack-friendly installation. Users who need input monitoring or additional serial devices should compare a model that explicitly includes those interfaces.
Built for Control Cabinet Installation
The rail-mounted ABS case makes the module easier to integrate into a structured cabinet than a bare circuit board. Status lights further improve visibility during installation and routine checks.
Protocol and Timing Support
Modbus RTU, Modbus TCP, MQTT, and timed flash operation cover both industrial command structures and connected control tasks. This variety supports projects with several possible integration paths.
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3. 8-Ch ESP32-S3 PoE Relay – Maximum Control Flexibility
8-Ch ESP32-S3 PoE Relay
Eight relays and digital inputs
Dual-mode wireless connectivity
Onboard RS485 interface
Integrated PoE Ethernet module
The Industrial 8-Ch ESP32-S3 WiFi Relay Module is the most connectivity-rich product in the list, with eight relays, eight digital inputs, Ethernet, Wi-Fi, Bluetooth LE, RS485, and PoE. It carries a supplied rating of 4.8 and centers on the ESP32-S3 dual-core microcontroller. That makes it a strong premium option for developers and advanced integrators who want more than a fixed protocol appliance.
Pros
- Ethernet, Wi-Fi, and Bluetooth
- Programmable ESP32-S3 platform
- Eight isolated digital inputs
- Supports wet and dry contacts
- PoE combines network and power
Cons
- More complex than fixed Modbus modules
- Arduino workflow may be required
- Higher feature complexity for beginners
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The digital inputs accept both passive dry contacts and active wet contacts, with bi-directional optocoupler isolation. Power isolation and other protection circuits are included, while the relays are rated up to 10A at 250V AC or 30V DC. The PoE module supplies both a network connection and power through one cable, simplifying installations where a compatible network connection and structured cabling are available.
Compared with the dedicated Modbus units, the ESP32-S3 model introduces a development workflow. The board supports Arduino IDE, so some projects may require custom firmware rather than only register configuration. That additional freedom is also the main drawback: beginners may find the software ecosystem more demanding than a ready-for-network web or Modbus interface. Firmware, security, and remote access policies must be managed carefully for exposed installations.
This is the best choice for sophisticated users who need wireless fallback, local serial devices, sensor inputs, and programmable logic in one module. It suits smart-building prototypes, agricultural controls, custom automation, and connected equipment where Ethernet alone is not enough. For a fixed Modbus installation with simpler administration, the higher-rated dedicated Ethernet module may be a more direct fit.
Three Ways to Connect
Ethernet, 2.4GHz Wi-Fi, and Bluetooth LE allow the same controller to fit different network plans. PoE over Ethernet can also simplify remote powered installations.
Inputs Expand Automation Potential
Eight digital inputs support both dry and wet contact sources. This allows the module to react to external sensors or switches rather than serving only as a remote output controller.
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4. 8-CH Ethernet Relay Module (B) – Complete Industrial Control
8-CH Ethernet Relay Module (B)
Eight outputs and eight inputs
Six communication modes
Modbus RTU and TCP
Three flexible power options
This 8-CH Ethernet Relay Module (B) is the strongest all-around recommendation in the guide, combining eight relay outputs with eight digital inputs and a supplied rating of 4.9. It supports Modbus RTU and Modbus TCP while also offering TCP server, TCP client, UDP, UDP multicast, HTTP, and MQTT modes. The combination of broad connectivity, inputs, and installation features makes it especially compelling for industrial automation.
Pros
- Highest supplied customer rating
- Exceptional input and protocol breadth
- Supports web configuration
- Flexible DC and PoE power
- Rail-mounted protective enclosure
Cons
- No stated onboard RS485
- Full feature set needs documentation
- Advanced configuration may intimidate beginners
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Configuration is flexible, with both software and web browser options, DHCP for dynamic IP assignment, and DNS support. The digital inputs accept dry and wet contacts and use bi-directional optocoupler isolation. Power can come from a DC power port, a screw terminal accepting 7-36V DC, or an IEEE 802.3af-compliant PoE port. An ABS rail-mount enclosure helps position the unit neatly in a control cabinet.
The main trade-off is that this broad feature set requires careful review of the documentation before deployment. A user selecting only Modbus may not need every listed network mode, while a programmer expecting custom firmware may prefer the ESP32-S3 products. The supplied information also does not identify an onboard RS485 interface, so local serial expansion would need separate consideration.
Buyers seeking a balanced, ready-to-integrate Ethernet relay module should look here first. It is appropriate for cabinets, remote equipment control, automated environments, and systems that need both outputs and feedback inputs. Its high supplied rating, extensive communication options, and flexible power design make it the most complete standard Modbus-oriented option here.
Inputs and Outputs in One Unit
Eight digital inputs complement eight relay channels, allowing feedback, interlocks, and sensor-driven operation. Optocoupler isolation helps protect sensitive control signals.
Adaptable Network Configuration
TCP, UDP, HTTP, MQTT, and Modbus modes cover several control architectures. Browser-based setup and DHCP support simplify deployment on managed or dynamic networks.
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5. 8-Ch ESP32-S3 Ethernet Relay – Developer-Friendly Automation
8-Ch ESP32-S3 Ethernet Relay
Eight outputs and inputs
Ethernet, Wi-Fi, and Bluetooth
Onboard RS485 connectivity
ESP32-S3 programmable platform
The Industrial 8-Ch ESP32-S3 Ethernet Relay Module combines an Ethernet port, eight relays, eight digital inputs, RS485, Wi-Fi, and Bluetooth LE. Its supplied rating of 4.6 reflects a strong reception while remaining below the leading fixed-protocol model and the newer PoE-equipped ESP32-S3 version. It is a particularly attractive option for developers who need Ethernet plus flexible local and wireless control.
Pros
- Broad wired and wireless options
- Eight isolated input channels
- RS485 expands industrial compatibility
- Supports Arduino development
- Comprehensive SDK and tutorials
Cons
- PoE not explicitly stated
- Custom development may be necessary
- No detailed enclosure specification
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Its ESP32-S3 processor uses a 32-bit LX7 dual-core architecture operating up to 240MHz and supports Arduino IDE development. Digital inputs accept passive and active signals with bi-directional optocoupler isolation, and the relay outputs are rated up to 10A at 250V AC or 30V DC. The supplied information also states that a comprehensive SDK, online development resources, tutorials, and technical support are available.
Unlike the premium ESP32-S3 model with an integrated PoE module, this product's description does not explicitly list PoE. That distinction may matter in installations where a single Ethernet cable must carry both data and power. The lack of a clearly described industrial enclosure in the supplied details may also make it less attractive for straightforward control-panel installations compared with the rail-mounted alternatives.
This relay module is best for makers, integrators, and technical users who want to create custom automation with Ethernet as the primary link. The combination of RS485, inputs, wireless radios, and development resources gives it a broad prototyping canvas. Users who only need a stable Modbus controller with enclosure and PoE may find the dedicated eight-channel module easier to deploy.
Open Development Environment
Arduino IDE support and the stated SDK, tutorials, and technical assistance make custom control logic more approachable. This is a key reason to prefer the model over a fixed-function controller.
Industrial and Wireless in One Board
RS485 supports local industrial devices, while Wi-Fi and Bluetooth add deployment flexibility. Eight inputs and outputs make it useful for complete control tasks rather than simple isolated switching.
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6. Waveshare 30-CH Ethernet Relay – Maximum Output Density
Waveshare 30-CH Ethernet Relay
Thirty relay output channels
Modbus RTU and TCP
PoE and wide DC input
Dedicated relay driver chip
The Waveshare 30-Ch Ethernet Relay Module is the obvious choice when output density matters more than a small footprint. It provides thirty relay channels, Ethernet control, Modbus RTU and Modbus TCP, PoE support, and an industrial rail-mount enclosure. Its supplied rating of 4.2 is solid, and its primary distinction is the ability to consolidate many independently controlled outputs in a single unit.
Pros
- Largest channel count listed
- Industrial rail-mounted housing
- PoE simplifies network cabling
- MQTT and timed control support
- Flyback diode protection included
Cons
- Larger physical footprint
- No digital inputs specified
- Considerable planning for channel use
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The module supports DC 7-36V input and PoE, MQTT control, and timed flash-on and flash-off operation. A dedicated relay driver chip with built-in flyback diode protection supports more stable output driving, while optocoupler isolation and reverse-proof circuitry add protection. Four LEDs and network indicators show microcontroller and signal-transmission status, helping installers diagnose wiring or communication problems.
The trade-off is physical and functional density rather than basic capability. Thirty relays require more panel space, careful terminal mapping, and enough power capacity for the intended loads. The supplied details do not list digital inputs, meaning a system that must read external sensor states may need a separate input module. A smaller eight-channel unit could be considerably easier to deploy in a modest installation.
This model makes sense for industrial control, smart-home equipment, smart agriculture, breeding, farming, and other scenarios where many network-controlled outputs can be consolidated. It is also attractive for installers who want PoE and Modbus in a rack-oriented enclosure. For a small number of loads, a less dense module will usually be easier to wire and maintain.
High Channel Count Simplifies Consolidation
Thirty channels can replace multiple smaller output devices. This reduces the amount of network equipment and cabinet space needed for large switching projects.
Protection for Driving Relays
The dedicated driver chip, flyback diode protection, optocoupler isolation, and reverse-proof circuit support dependable operation. Indicators help confirm that commands and network signals are moving correctly.
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7. Waveshare ESP32-S3 PoE Relay – Polished Development Platform
Waveshare ESP32-S3 PoE Relay
Eight-channel programmable controller
Isolated RS485 interface
Dual-mode wireless connectivity
PoE Ethernet connectivity
The Waveshare Industrial 8-Channel ESP32-S3 WiFi Relay Module is built around an Xtensa 32-bit LX7 dual-core processor running up to 240MHz. It combines an Ethernet chip, PoE option, isolated RS485, Wi-Fi, and Bluetooth LE. The supplied rating of 4.7 makes it one of the strongest choices for buyers who want a polished programmable controller rather than a fixed Modbus-only appliance.
Pros
- PoE and Ethernet together
- Isolated industrial RS485
- Bluetooth and Wi-Fi included
- USB Type-C management support
- Wide DC input and RTC
Cons
- Digital input count not specified
- Optional PoE version requires checking
- Custom firmware may be required
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The relay output is rated up to 10A at 250V AC or 30V DC. The module supports passive and active digital input with bi-directional optocoupler isolation and linkage control. An onboard USB Type-C connection handles power, debugging, and firmware downloading, while a 7-36V input range and an RTC support broader installation and scheduled-task requirements. Built-in indicators assist with device monitoring.
A few details need confirmation before purchase. The product description mentions PoE as an optional version, so the selected listing must actually include it. It also discusses digital input support without clearly stating how many input channels are provided, unlike the ESP32-S3 products that explicitly list eight. Finally, programmable behavior means users may need to build or adapt firmware, which is less convenient than web configuration on fixed-function modules.
This model suits developers who want local RS485, wireless access, Ethernet, PoE convenience, and a modern processor in an integrated platform. It can work well for custom building controls, environmental automation, and prototypes that need scheduling. Buyers prioritizing a clearly specified input count or simple out-of-box configuration should examine those points before committing.
Programming and Service Access
USB Type-C supports power, debugging, and firmware downloads, which simplifies development and maintenance. The stated Wiki resources can reduce setup friction for common tasks.
Flexible Control and Scheduling
Ethernet, Wi-Fi, Bluetooth LE, and isolated RS485 provide several ways to connect. The RTC also supports scheduled tasks, making timing-dependent automation easier to implement.
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8. 8-CH Ethernet Relay Module (B) – Balanced Input Control
8-CH Ethernet Relay Module (B)
Eight relay and input channels
Modbus RTU and TCP
PoE and DC power
Dedicated relay driver chip
This Waveshare 8-Ch Ethernet Relay Module (B) adds eight digital inputs to eight relay outputs while retaining Modbus RTU and Modbus TCP support. It also offers PoE, broad DC input, MQTT control, timed flash operation, and a rail-mounted ABS enclosure. The supplied rating of 4.2 indicates a solid product, particularly for users who need both switching and feedback in a single Ethernet controller.
Pros
- Balanced outputs and inputs
- Supports dry and wet contacts
- Debounced input handling
- Linkage and toggle control
- Industrial rail enclosure
Cons
- Network-mode list not fully detailed
- No onboard RS485 specified
- Requires some configuration knowledge
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Its digital inputs support passive and active contacts with bi-directional optocoupler isolation and a built-in debouncing algorithm. Relays can respond to digital input linkage or operate in toggle mode, which helps implement interlocked or stateful control. A dedicated relay driver chip and flyback diode protection support output stability, while reverse-proof circuitry helps reduce risk from incorrect connections.
Compared with the highest-rated eight-channel Module (B), the specification summary here does not list the same breadth of TCP, UDP, HTTP, MQTT, and DHCP configuration modes. The distinction may not matter for a straightforward Modbus system, but it becomes relevant for users who need a specific client, server, or browser-based workflow. The supplied data also does not identify an RS485 interface.
Choose this module when a project needs eight outputs, eight protected inputs, timed commands, and PoE without moving into custom firmware. It is appropriate for equipment control, automation panels, and installations where a rack-mounted enclosure simplifies maintenance. For maximum protocol breadth, the other similarly named Module (B) should receive closer attention.
Debounced and Protected Inputs
Bi-directional optocoupler isolation and debouncing make the digital inputs more suitable for real switch and sensor signals. This reduces unnecessary false events from mechanical contact changes.
Flexible Relay Logic
Linkage control allows an input event to influence an output, while toggle mode supports persistent state changes. These options reduce the amount of external control logic required.
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9. Pinhaijing LAN Ethernet Relay – Compact Two-Channel Control
Pinhaijing LAN Ethernet Relay
Two Ethernet-controlled relays
TCP and UDP operation
Built-in web server
Five to twenty-four volt input
The Pinhaijing LAN Ethernet 2 Way Relay Board is the most compact and approachable option in this guide. It provides two Ethernet-controlled relays, TCP and UDP support, a web server, and a supplied rating of 4.8. Unlike the larger industrial modules, it targets embedded projects where a small board and straightforward browser control are more valuable than high channel count.
Pros
- Compact and easy to embed
- Simple web-based controller
- Password-protected remote access
- Wide low-voltage input range
- Individual relay status lights
Cons
- Only two relay channels
- No PoE or Modbus stated
- No digital input specification
- Bare-board construction
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Remote cloud control is described as using local password protection, which is an important basic security measure for an internet-accessible controller. The board accepts 5V or 9-24V input, uses 1.6mm FR-4 construction, and measures 6.8 by 4.8cm. A power indicator and individual relay status lights provide basic operational feedback, while mounting holes simplify physical installation.
The obvious limitation is capacity. Two relays cannot replace an eight- or thirty-channel module in a larger automation system, and the supplied details do not mention digital inputs, PoE, Modbus, isolation circuits, or a rail-mounted enclosure. TCP and UDP control is suitable for many custom applications, but it may not satisfy integrators who need standard industrial register protocols or cloud-ready MQTT workflows.
This board is a strong fit for home automation experiments, small appliance controls, equipment prototypes, and embedded network switching where two outputs are sufficient. It is also easier to prototype with than a large industrial controller. For a permanent high-channel installation, choose a module with more protection, enclosure options, and formal protocol support.
Simple Embedded Networking
The small board, web server, and TCP or UDP control make it straightforward to build lightweight network-controlled devices. Password protection adds a necessary layer for remote access.
Practical Low-Voltage Design
Support for 5V and 9-24V input accommodates common bench and embedded supplies. Individual status lights and mounting holes support easier assembly and diagnosis.
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10. 8-CH Modbus PoE Relay – Straightforward Network Control
8-CH Modbus PoE Relay
Eight Ethernet relay channels
Modbus RTU and TCP
Six supported network modes
PoE and wide DC input
The 8-CH Ethernet Relay Module is a conventional industrial switching controller with Ethernet, Modbus RTU and Modbus TCP, and eight relay outputs. Its supplied rating is 4.0. It offers TCP server, TCP client, UDP, UDP multicast, HTTP, and MQTT modes, creating a broad set of ways to connect equipment and control software.
Pros
- Broad network mode selection
- Standard Modbus command support
- Web and software configuration
- DHCP and DNS support
- Rail-mounted enclosure
Cons
- No digital inputs specified
- Fewer features than leading models
- No onboard RS485 stated
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Configuration can be performed through software or a web browser. DHCP supports dynamic IP assignment, and DNS allows connection through a domain name server. Power options include a DC power port, screw terminals accepting 7-36V DC, and an IEEE 802.3af-compliant PoE port. A rail-mounted ABS enclosure and four LED and network indicators support organized installation and visible troubleshooting.
Timed flash-on and flash-off behavior is included, along with optocoupler isolation for the relay circuitry. However, the supplied details do not list digital inputs, an RS485 interface, or MQTT-specific isolation features. This makes the module less expansive than the highest-rated 8-CH Ethernet Relay Module (B), even though both support a similar collection of network modes.
The module is a solid choice for users who need standard eight-channel Ethernet control and prefer a fixed industrial interface over custom firmware. It suits automation panels, remote equipment, and smart-building projects using Modbus or one of the listed network modes. Buyers who need sensor feedback or local serial expansion should review the input-equipped and ESP32-S3 alternatives.
Multiple Network Operating Modes
Server, client, UDP, multicast, HTTP, and MQTT modes let the controller fit different network architectures. This is helpful when a project evolves beyond a single integration method.
Flexible Installation Power
DC plug, wide-range screw terminal, and compliant PoE options allow installers to use available power sources. Browser configuration and DHCP reduce initial network setup effort.
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Buying Guide – How to Choose the Best Ethernet Relay Module
Choosing an Ethernet relay module means balancing output count, input feedback, protocol support, electrical protection, power method, physical construction, and the level of customization required. The best choice is the one that matches the installation environment and the software ecosystem already used by the installer.
Relay and Input Count
Begin by counting every load that must be switched independently, then add enough capacity for reasonable future expansion. The modules in this guide range from two relays to thirty, while the most capable eight-channel units also provide eight digital inputs. Inputs matter when buttons, sensors, interlocks, or equipment feedback must be read by the controller rather than merely controlled by it.
Choose a channel count that simplifies distribution without creating an oversized and difficult-to-wire system. Eight channels are versatile for a single panel, while thirty can consolidate a large installation. A two-channel board is more appropriate for compact prototypes or isolated appliances.
Ethernet and Wireless Connectivity
Confirm whether Ethernet is mandatory or simply one option among several. Dedicated industrial modules prioritize wired control, while the ESP32-S3 products add 2.4GHz Wi-Fi and Bluetooth LE. Wireless access can simplify deployment where cabling is difficult, but it also introduces considerations involving signal coverage, network security, and predictable recovery after an outage.
For a fixed cabinet, Ethernet is often the most consistent choice. For flexible or custom installations, a controller supporting Ethernet, Wi-Fi, and Bluetooth provides more ways to integrate. Verify whether the product version actually includes every advertised connectivity option.
Protocol and Software Compatibility
Match the module's command format to the equipment that will supervise it. Modbus RTU and Modbus TCP are common in industrial environments, while HTTP, MQTT, TCP, and UDP can be convenient for connected devices and custom software. A programmable ESP32-S3 module can support custom logic, but it generally requires firmware development rather than only register-level configuration.
Look for documented register maps, command examples, configuration utilities, and application demonstrations. The most useful controller is the one your team can operate and maintain confidently. Confirm TCP client or server behavior as well when a host, cloud service, or supervisory system has a specific connection model.
Power Supply Architecture
Several modules accept both broad-range DC input and PoE, which can simplify cabinet wiring. PoE carries network data and power over one cable, provided the network switch or injector supports the required PoE standard. Models offering a plug-in DC port and screw terminals give additional flexibility for installations without PoE infrastructure.
Calculate the power available for the relays and attached loads rather than considering only the controller's own supply. Verify voltage range, connector type, PoE standard, and grounding requirements. A controller that works well with a bench supply may need a more carefully engineered supply in a permanent installation.
Isolation and Electrical Protection
Optocoupler isolation, power isolation, reverse-proof circuits, and flyback diode protection can reduce the risk of interference, wiring mistakes, and electrical stress. The listed relay contact rating of up to 10A at 250VAC or 30VDC describes maximum contact capability, not permission to switch every load at that level. Inrush current, coil characteristics, switching frequency, and the device manufacturer’s guidance all matter.
Prefer models that clearly identify protection features and status indicators. Isolation is particularly valuable when the control electronics and field devices share an enclosure. For high-current or inductive loads, verify that the relay type, protection, wiring method, and safety provisions are appropriate for the application.
Enclosure and Mounting Style
Rail-mounted ABS enclosures are well suited to organized control cabinets, while compact bare boards are easier to include inside a custom enclosure. The supplied dimensions and mounting details matter when space is limited. An industrial enclosure can simplify cable routing and reduce exposure, but it does not by itself guarantee compliance with local installation rules.
Decide whether the module will be a finished control device or a component within a larger enclosure. Choose the physical format that suits the enclosure, ventilation, wiring space, and service access. Also consider indicator visibility because network and relay status lights can shorten troubleshooting time.
Programmability and Documentation
A fixed-function module is often easier to deploy when it already supports the exact required protocol. A programmable ESP32-S3 board offers much greater flexibility for custom behavior, local schedules, wireless access, and integration with sensors. That flexibility comes with responsibility for firmware, updates, recovery procedures, and network security.
Review the stated SDK, tutorials, Wiki resources, Arduino support, and technical assistance before choosing a programmable unit. For a non-programmer, a browser-configurable controller may be more appropriate. For a developer, documented examples and an active development workflow can be more valuable than any extra fixed protocol.
Environmental Suitability
The products are described as industrial or industrial-grade, but those terms should not be treated as universal guarantees. Consider temperature, humidity, dust, moisture, vibration, electrical noise, and the enclosure environment where the module will operate. Conductive grounding, cable segregation, surge considerations, and correct fusing are equally important for reliable operation.
The most capable features do not compensate for an unsuitable environment. Ensure the module, power source, wiring, and connected load are all rated for the installation. If the enclosure is exposed to condensation, heavy dust, or outdoor weather, use an appropriate protective enclosure and verify that its temperature limits remain acceptable.
How to Use and Care for Your Ethernet Relay Module
Start by creating a wiring plan that identifies every relay load, digital input, power source, Ethernet route, protective earth connection, and required network address. Confirm that the selected module version supports the protocols and power method you intend to use. With power disconnected, terminate the input and load wiring according to the product documentation, then check polarity and voltage ratings before energizing the controller.
Configure the network settings through the supported software or browser interface, or load and configure firmware when using a programmable ESP32-S3 model. Assign a unique address, test each relay with a harmless low-load connection, and verify each digital input. After confirming local operation, test commands over the intended Ethernet, Modbus, MQTT, TCP, UDP, or wireless path and confirm that the module's status indicators reflect the expected activity.
For long-term use, secure cables, keep ventilation paths clear, tighten terminals according to the manufacturer's instructions, and avoid exceeding the relay contact or system power limits. Update documentation with addresses and wiring changes, restrict access with strong credentials and appropriate network controls, and periodically inspect for heat, discoloration, loose connections, and abnormal noise. Test operation after maintenance so that a successful network response is not mistaken for proof that the physical output is functioning correctly.
Frequently Asked Questions
What is an Ethernet relay module used for?
An Ethernet relay module lets a computer, controller, or network service operate electrical switches remotely. It is useful for controlling lights, pumps, valves, alarms, access equipment, and industrial machinery. Its network interface also makes scheduled, monitored, or centralized control easier than a standalone manual switch.
Do all Ethernet relay modules support Modbus?
No. Many of the industrial eight- and thirty-channel products in this guide support Modbus RTU and Modbus TCP, but the compact Pinhaijing board emphasizes TCP, UDP, and web-server control. The ESP32-S3 models support programmable operation and may use Modbus through RS485 with custom or supplied software. Check the exact protocol and command documentation before selecting a controller.
Can PoE power an Ethernet relay module?
Several models in the guide support PoE, allowing network data and power to travel over one Ethernet connection. Compatibility depends on the exact module version and the connected switch, injector, or controller. One listed product mentions PoE as an optional version, so buyers should verify the configuration included in their chosen listing.
How many relays do I need?
Count the independently switched loads in the installation and include any planned expansion. A two-channel board suits a small prototype, while eight channels cover many automation panels and thirty channels consolidate larger systems. Digital inputs should be counted separately when the controller must read switches, sensors, interlocks, or equipment status.
What is the difference between dry-contact and wet-contact inputs?
A dry contact applies no voltage to the input and simply closes or opens a circuit, like a passive switch. A wet contact already presents a voltage or powered signal. Modules that support both can accommodate different sensor types, but installers must still observe each input's voltage and polarity requirements.
Are these relay modules suitable for controlling household appliances?
Some models state that their relays can directly control 220V AC appliances or devices below 30V DC. The contact rating is a maximum capability rather than a blanket safety approval for every load. For mains equipment, follow local electrical rules, use appropriate enclosures and protection, and consult a qualified electrician when needed.
Should I choose a fixed Modbus module or an ESP32-S3 model?
A fixed Modbus module is generally easier to deploy when it supports the required protocol and configuration method. An ESP32-S3 model is better when you need custom firmware, Wi-Fi, Bluetooth, RS485, or flexible application logic. The programmable route requires more software expertise, while a fixed module often offers a shorter path from installation to operation.
How do I keep network-accessible relay modules secure?
Use strong local credentials, change any default access settings, restrict the controller to required network segments, and avoid direct exposure to the public internet without a properly secured gateway or VPN. Maintain current firmware, log unexpected commands, and document the addresses and behaviors of every output. Network security is especially important because a connected relay can operate physical equipment.
Final Thoughts on Choosing the Best Ethernet Relay Module
The 8-CH Ethernet Relay Module (B) with digital inputs stands out as the strongest all-around option because it combines eight outputs, eight protected inputs, several network modes, Modbus support, flexible power, and a high supplied rating. The 8-Ch ESP32-S3 WiFi Relay Module is the premium choice for programmable control, wireless access, RS485, and PoE, while the Pinhaijing LAN Ethernet 2 Way Relay Board is the practical compact option for smaller embedded projects.
Prioritize the requirements that cannot be changed after deployment. Verify channel counts, input types, protocol compatibility, PoE version, isolation features, enclosure requirements, and the availability of documentation before purchasing. Fixed-protocol users should favor simple configuration, while developers may gain more from an ESP32-S3 platform and its custom control potential.
Ratings, availability, included accessories, and pricing can change over time, so review the current listing before ordering. Comparing the supplied specifications against a written project plan will produce a more reliable result than choosing solely by channel count or product name. Always confirm the exact module version and follow appropriate electrical and network security practices during installation.