IoT Edge Gateways Emerging as Enterprise Connectivity Option

Edge gateways are using the MQTT protocol as a way to enable secure data flow between edge devices and the cloud, and create a new class of IIoT connectivity.

Industrial IoT edge gateways represent an emerging product category and key technology for connecting both legacy controllers and edge devices to the Internet of Things (IoT). Along with integrating a variety of protocols for networking, they provide resources for managing data storage and analytics, along with enabling secure data flow between edge devices and cloud services.

New Option for IIoT Applications

The idea behind edge gateways is to provide a way to use data already created by operational technology and translate data from existing control applications into IoT-friendly formats that can be easily accessed via the cloud. One argument is that, because data is often aggregated and displayed for operators on a Human Machine Interface (HMI), the same data can be presented to other users and provides a powerful additional capability for IoT applications.

This is the approach that Maple Systems is taking with new additions to its HMI line-up by offering extensive libraries of industrial protocol drivers for operating on different network architectures. For example, the company’s HMI5097DXL offers three serial ports and a CANbus port which can operate simultaneously utilizing over 200 different protocols. Two Ethernet ports can be used for real-time industrial control network demands, external network connections and IIoT functionality.

By building MQTT support into the HMI, data can be organized into topics and presented to upstream IT applications in a flexible, modular and efficient way. According to the Maple Systems website, “The MQTT broker is responsible for maintaining client connections and sending/receiving messages. Client devices, edge gateways, and IT applications (or publishers/subscribers in MQTT language), are freed up to focus on producing and consuming data.”


To realize benefits of the IIoT, data transmitted by an edge gateway-enabled HMI can use the MQTT protocol to communicate with multiple types of devices. MQTT is organized into topics which can contain single data points, or a group of related data, and the HMI can be configured to transmit data from a specific topic whenever a change occurs, or on a periodic basis, lowering the bandwidth required for connection. Image source: Maple Systems


It’s easy to see how, as MQTT is a lightweight protocol, and up to 1,000 connected clients can be easily supported, the ability to publish data as topics can provide an effective method for monitoring a specific machine or industrial process. The more difficult task seems to be the application programming and analytics required to transform raw data into actionable information.

netIOT Edge Gateway

Another excellent example of edge gateway technology is the netIOT product line from Hilscher, which can act as a bridge between the IT (information technology) and OT (operations technology) domains for data collection, aggregation and abstraction tasks.

The architectural vision of the Hilscher products is to leverage techniques and protocols that are already available for “crossing the edge” including, for example, HTTP and web services. But to address the needs of automation networking, the hard real-time benefits of protocols like PROFINET and EtherNet/IP will offer additional networking options.

The approach is to use OPC UA as a technology that can exist on both sides of the divide between IT and OT, along with use of the MQTT protocol for transmitting data over long distances for SCADA implementations. The thinking is that both MQTT and OPC UA will become de facto standards for IIoT applications, and that AMQP has the potential to support data management functions needed for MES and ERP connectivity.

An embedded module for building IIoT-ready smarter sensors can be enabled using netIOT interface technology. Image source: Hilscher

According to the Hilscher website, the netIOT Edge is more than a simple gateway, providing an independent computing platform capable not only of conventional gateway tasks but also of acquiring, processing, storing and analysing data locally, as well as interfacing data to cloud-based systems. It can be deployed as a passive device that simply listens to traffic on a network, or as an active device handling complex functions such as rule-based decision making.

Looking ahead: edge solutions

With the Industry 4.0 initiative in Germany making progress, along with the work of the Industrial Internet Consortium, the Avnu Alliance, OPC UA, and the IEEE 802.1 Time Sensitive Networking standards groups, there is an unprecedented effort to unify industrial connectivity standards. But edge gateways, on the other hand, provide a way that companies can immediately utilize data from edge devices to implement solutions that don’t require these other technologies to move ahead with IoT applications.

Use of MQTT, and potentially AMQP, provides connectivity options for linking to cloud services, and new options including OPC UA make implementing these systems more realizable.  Edge gateway technology is not only preparing automation networks for edge computing and data aggregation, but also provide a system architecture for configuring and monitoring IoT field devices that typical PLC and PC-based control systems aren’t able to implement.


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