NetRelay IoT Development Board

What is the NetRelay IoT Development Board?

NetRelay IoT Development Board is an industrial IoT and automation platform designed to connect software applications with sensors, relays and physical field equipment. Ethernet, Wi-Fi and PoE connectivity make it suitable for factories, facilities, server rooms, agriculture, building automation and remote equipment management.

Relay outputs

NetRelay includes 4 relay outputs rated for switching loads up to 250 V AC and 10 A. Each relay provides normally open, normally closed and common contacts.

The relays can control lighting, fans, sirens, barriers, solenoid valves, pump control circuits, contactors, modems and similar equipment. Suitable contactors, protection devices and drivers should be used separately for high-power motors and inductive loads.

Digital inputs

The device includes 4 digital inputs. Dry-contact devices, magnetic door sensors, float switches, alarm outputs, thermal relays, limit switches and machine status contacts can be connected to these inputs.

Digital input changes can be monitored through the web interface, transmitted to central software through MQTT or HTTP and used to trigger configured relay actions.
https://github.com/mlteknoloji/mqttserver

Analogue inputs and sensor support

NetRelay provides 4 switched analogue inputs with increased gain. Compatible sensors and expansion modules can be used to measure temperature, light, pressure, humidity, soil moisture, electrical current and similar analogue values.

Sensor values can be compared with configured thresholds. A fan can start when temperature rises, irrigation can begin when soil moisture falls or measured values can be transmitted to a central system.

Ethernet and Wi-Fi connectivity

The device can operate through wired Ethernet or 2.4 GHz Wi-Fi. Wi-Fi access point and client modes allow it to connect to an existing wireless network or create its own network during initial configuration.

Ethernet provides stable communication for critical automation projects, while Wi-Fi provides installation flexibility where network cabling is not practical.

PoE and power options

NetRelay supports 802.3af/at PoE, allowing power and network data to travel through a single Ethernet cable. This simplifies installation in control panels, server cabinets, ceilings and remote locations where access to a power outlet is limited.

The device can also be powered through a 7–28 V DC input and used with common 12 V or 24 V industrial power supplies. When the PoE switch is connected to a UPS, NetRelay can continue operating during mains power interruptions.

Expansion interfaces

NetRelay provides 2 external I2C ports, 1 SPI port, 1 UART TTL serial port and additional expansion connections. Optional RS485 support allows field devices using Modbus or similar serial communication standards to be integrated.

The expansion connections support custom sensors, displays, memory modules and communication accessories.

RTC time module

With the optional DS3231 RTC module, the device can retain date and time information without an internet connection. Time-based automations, daily schedules and relay operations can therefore continue independently from online time services.

Sunrise and sunset calculations can be used to automate park, garden, residential complex and building lighting.

MicroSD data logging

An optional MicroSD module can record sensor values, digital input changes, relay actions and system events locally.

Local recording during internet or server outages helps reduce data loss in critical field applications.

DIN rail enclosure

NetRelay is supplied in an enclosed housing compatible with standard DIN rails used in industrial control panels. This provides a safer, cleaner and faster installation than using an exposed circuit board.

Relay, input, power and network connections remain easily accessible inside the panel. The product is delivered as a field-ready enclosed device rather than only as an electronic circuit board.

Internal monitoring

The device can monitor its operating temperature and supply voltage. These values can support system health checks, early detection of power problems and remote maintenance processes.

Supported communication protocols

NetRelay supports HTTP GET and POST, MQTT, WebSocket, TCP server and TCP client communication. It can therefore be integrated with custom applications, production monitoring systems, SCADA platforms, Home Assistant, Node-RED, ERP systems and central management dashboards.

Applications developed with Python, Node.js, C#, C++, PHP, ASP, Delphi and VB.NET can read inputs and control relay outputs.

Ping Watchdog

Ping Watchdog periodically checks IP devices such as modems, routers, cameras, NVR systems, access points and servers. When a target device stops responding for a configured period, NetRelay can automatically power-cycle the relevant relay.

This allows unresponsive network devices to restart automatically without requiring technical personnel to visit the site.

Hardware specifications

• 4 digital inputs
• 4 relay outputs rated up to 250 V / 10 A
• Normally open, normally closed and common relay contacts
• 4 switched analogue inputs with increased gain
• Wired Ethernet connectivity
• Wi-Fi access point and client modes
• 802.3af/at PoE support
• 7–28 V DC power input
• 2 external I2C connections
• 1 SPI connection
• 1 UART TTL serial connection
• Optional RS485 connection
• Optional DS3231 RTC module
• Optional MicroSD data logging module
• Supply voltage and board temperature monitoring
• Enclosed housing compatible with standard DIN rail mounting
• Built-in Turkish and English web interface

Application areas

• Factory and production line automation
• Machine operation and fault monitoring
• Server room temperature and connectivity monitoring
• Remote restart of modems, cameras and network equipment
• Smart irrigation and greenhouse automation
• Water tank and well pump control
• Licence plate recognition and parking barrier integration
• Energy and environmental data monitoring
• Residential complex, park and building lighting automation
• Transmission of alarm and dry-contact signals over a network

Extensible architecture

NetRelay can be used directly with its built-in web interface and existing firmware or integrated into custom software projects. Custom firmware can be developed using environments such as ESP-IDF, PlatformIO and Arduino IDE.

This architecture makes NetRelay more than a network relay controller and turns it into a comprehensive IoT development platform for sensing, communication and automation projects.