Embedded IoT Gateways: Connecting Legacy Devices and Sensors

Introduction

The Internet of Things (IoT) is transforming industries by connecting physical devices and assets to the internet. This enables data collection, remote monitoring, control, and analytics. However, many existing devices and sensors lack native internet connectivity. Embedded IoT gateways provide a solution to bridge these legacy devices to the IoT.

In this article, I will provide an in-depth look at embedded IoT gateways. I will cover:

• What are embedded IoT gateways and why are they needed
• Major components and architecture
• Key protocols and standards
• Security considerations
• Use cases across industries
• Leading gateway vendors and products

What are Embedded IoT Gateways?

Embedded IoT gateways are purpose-built devices that enable connections between sensors, machines, and other endpoints to the cloud. They act as a bridge between legacy devices without internet connectivity and an IoT platform.

Gateways provide protocol translation, data filtering, security, and other functionality to facilitate useful data flows. They also often manage connections to a diverse set of heterogeneous endpoints.

The key value of IoT gateways is simplifying the integration of existing equipment and sensors into new IoT applications. This avoids costly replacement of devices while still enabling IoT benefits like predictive maintenance, efficiency optimizations, and automation.

Major Components and Architecture

Embedded IoT gateways typically contain both hardware and software elements:

Hardware

• Processor – Often an ARM-based processor, providing computing power for the gateway. More intensive applications may require multi-core processors.
• Memory – RAM and storage to run the gateway software and buffer data.
• Networking interfaces – Wired and wireless connectivity like Ethernet, WiFi, Bluetooth, Cellular, etc. This allows connections to devices, routers, and the cloud.
• Protocol support – Chipsets for interfaces like digital I/O, RS232, RS485, and Modbus. This enables connectivity to PLCs, sensors, meters, drives, and more.
• Security capabilities – Hardware security modules like TPMs (trusted platform modules) help provide secure key storage, encryption, and authentication.

Software

• Real-time OS – Handles scheduling processes and resource allocation. Often Linux-based.
• Device drivers – Enables communication with the various connected endpoints. Supports many protocols.
• Protocol stacks – Implements standardized protocols like MQTT, OPC-UA, and Modbus.
• Data processing – Functionality for filtering, transforming, aggregating, and encrypting data flows.
• Remote management – Allows monitoring, configuring, updating, and managing the gateway remotely.
• Edge logic – Some gateways can run local analytics or rules engines for edge intelligence.

A generic architecture of an IoT gateway. Source: ResearchGate

Gateways manage traffic between field devices and the cloud platform using both wired and wireless networking. They run protocol stacks to communicate with diverse endpoints. Data processing, security, and remote management capabilities provide centralized control.

Key Protocols and Standards

IoT gateways support a wide set of protocols for northbound and southbound communications:

Northbound protocols connect the gateway to the cloud and network core:

• MQTT – Lightweight publish-subscribe messaging protocol for IoT telemetry
• AMQP – Advanced Message Queuing Protocol for reliable messaging
• OPC-UA – Open connectivity standard for industrial automation
• LWM2M – Lightweight M2M protocol by Open Mobile Alliance
• HTTP/S – Simple RESTful APIs for web connectivity

Southbound protocols connect to field devices and sensors:

• Modbus – Serial communications standard for connecting industrial devices
• BACnet – Building automation protocol for HVAC, lighting, access, and fire systems
• CAN bus – Controller Area Network protocol for automotive and industrial apps
• Bluetooth – Wireless protocol for audio, peripherals, and IoT
• Zigbee – Mesh networking standard for low-power IoT devices
• Proprietary – Vendor specific protocols, often via serial or IP

This flexibility to support new and legacy protocols is a key benefit of gateways.

Security Considerations

Security is crucial for IoT gateways since they aggregate sensitive data and controls from across an organization. Best practices include:

• Encrypting all data in transit and at rest
• Secure boot to ensure only trusted software is executed
• Trusted Platform Modules (TPMs) for hardware-based security functions
• Regular security audits and firmware updates
• Authentication and access controls for gateway management
• VLAN segmentation of critical network traffic
• Monitoring for suspicious network activity
• Disabling unused hardware interfaces, protocols, ports, and services

A secure gateway architecture is essential as a foundation for building safe and resilient IoT systems.

Use Cases Across Industries

IoT gateways deliver value across many verticals:

Industrial

• Connecting legacy PLCs, sensors, and drives to enable industrial analytics and predictive maintenance
• Aggregating data from machines in a factory for centralized monitoring

Energy

• Collecting usage data from smart meters for utility billing and grid analytics
• Monitoring operations in oil fields, pipelines, and generation plants

Building Automation

• Bridging building systems like HVAC, lighting, and physical security to facility management dashboards
• Enabling smartphone control of buildings using legacy automation infrastructure

Transportation

• Ingesting telematics data from commercial truck fleets for fleet tracking and diagnostics
• Connecting sensors across railway cars and stations for condition monitoring and analysis

Agriculture

• Pulling data on soil moisture, crop health, and equipment status from the field into farm management software
• Allowing control of irrigation systems and agricultural machinery remotely

The applications are wide-ranging across any industry with legacy equipment.

Leading Vendors and Products

The gateway ecosystem includes hardware manufacturers and software platform vendors:

Hardware Manufacturers

• Cisco (IR809, IR829)
• Dell (Edge Gateway)
• Huawei (AR502H)
• Siemens (SIMATIC IOT2000)
• Lantronix (EG4100)

Software Platforms

• Microsoft Azure IoT Edge
• AWS IoT Greengrass
• Google Cloud IoT Edge
• IBM Watson IoT Platform
• Hitachi Lumada

These reliable commercial solutions provide full-featured gateways that integrate with major cloud providers. Most offer developer-friendly APIs and software stacks to simplify building IoT apps.

There are also many open source gateways leveraging platforms like Raspberry Pi for custom use cases.

Conclusion

Embedded IoT gateways are essential products enabling digital transformation across industries. They overcome the connectivity challenges of legacy devices to bridge operational technology with modern IT infrastructure. With their protocol flexibility, processing power, and security capabilities, gateways will remain a key component of IoT architectures for years to come. Leading technology and platform vendors provide proven gateway solutions to accelerate organizations’ journeys toward greater connectivity, automation, and insight.