16-Channel Ethernet Relay Module – Modbus, PoE Support, Isolation Protection

Jargon buster

Plain-language definitions for the technical terms used above.

DC

DC means direct current, where electricity flows in one constant direction, as supplied by batteries, USB ports and many plug-pack power supplies. When a product specifies DC, it runs from a DC supply rather than mains AC, so you need to provide the correct voltage and polarity.

DIN

As a pin label, DIN stands for 'data in', the input through which a device receives serial data from a controller, as found on SPI displays, LED drivers and other serial modules. DIN can also refer to the German standards body of that name, as in a round multi-pin DIN connector or DIN-rail mounting.

DIN rail

DIN rail is a standard metal mounting rail used inside industrial electrical cabinets. When a product is DIN rail mountable, it can be clipped neatly alongside power supplies, relays and other automation hardware in a panel.

IoT

Short for Internet of Things, meaning physical devices that connect to networks or the internet to send data or be controlled remotely. It matters if you want projects such as connected sensors, remote controls or classroom data-logging activities.

LED

A light-emitting diode (LED) is a small electronic component that emits light when current flows through it in the correct direction. Because it only conducts one way, its polarity matters, and a through-hole LED must be soldered the correct way around to light up.

Modbus

Modbus is an industrial communication protocol used by many meters, sensors, PLCs and automation devices. When a product lists Modbus support, it is generally easier to integrate with existing industrial equipment that speaks the same protocol.

Modbus RTU

Modbus RTU is a version of the Modbus protocol that runs over serial wiring, commonly RS485. When a product lists Modbus RTU, it can connect to industrial sensors, meters or drives that use serial Modbus rather than Ethernet.

Modbus TCP

Modbus TCP is a version of the Modbus protocol that runs over Ethernet networks. When a product lists Modbus TCP, it can connect to industrial systems that communicate over standard network cabling.

MQTT

A lightweight messaging protocol often used for IoT devices to publish and receive data through a server called a broker. It matters for home automation and sensor networks because it is simple, efficient, and widely supported.

PoE

Power over Ethernet lets one Ethernet cable carry both network data and electrical power. This is useful when installing a device where running a separate power adaptor would be difficult.

Relay module

A relay module uses an electrically controlled switch to let a low-power microcontroller control a separate circuit. It matters when switching devices that need different voltages or more current than a microcontroller pin can safely handle.

Terminal block

A terminal block is a connector that joins wires together in a neat, removable, or serviceable way, usually clamping each wire under a screw or spring instead of soldering. It makes it easier to connect, change, or service wiring without permanent joints.