HMIs Double as Edge-of-Network Gateways
The Industrial Internet of Things (IIoT) is here and it’s changing
the way manufacturers think about business. These days, everyone
wants to be wirelessly connected, synced up and remoted in. You name
it, we want to be connected to it. Within the manufacturing
industry, there is great need and desire for more connectivity and
access to valuable data from our factory machines.
Enter the edge gateway. The edge gateway unlocks valuable data
created by existing assets. In the manufacturing sphere, edge
gateway devices translate data used by control applications into an
IIoT-friendly format, sending that data to the Internet for use by
An edge gateway device must fulfill key requirements. It must be
efficient, reliable and scalable. It must also be easy to configure
and put into service. Above all, it must be secure. And it must
communicate with a wide range of existing equipment and support
emerging IIoT protocols such as MQTT (formerly MQ Telemetry
Transport). This is an ISO standard (ISO/IEC PRF 20922)
publish-subscribe-based “lightweight” messaging protocol for use on
top of the TCP/IP protocol. It is designed for connections with
remote locations requiring a small code footprint or a limited
An HMI is a good candidate for serving as the edge gateway device.
The HMI, the operator’s window into the machine, can easily be
extended to play the same role in the virtual world. The HMI is the
place where data is aggregated, filtered and presented to the
operator. This same data can easily be presented to users connecting
to the HMI through the IIoT.
A primary requirement of the IIoT is interoperability. The dizzying
array of communication protocols used in manufacturing today present
a significant barrier. Fortunately, modern HMIs possess extensive
libraries of industrial protocol drivers operating on different
network architectures. This makes Maple Systems HMIs the perfect
means of handling the interoperability challenge.
Data transmitted by the edge gateway-enabled HMI must be presented
to upstream IT applications in a way that is flexible, modular and
efficient. The MQTT feature available on Maple Systems HMIs
exemplifies the power of this protocol. MQTT is organized into
topics that can contain single data points or a group of related
data points. The HMI can be configured to publish data to a specific
topic whenever a change arises, or periodically, lowering the
bandwidth needed for data transmission.
A fundamental advantage of MQTT is that data goes to a central
“broker” instead of directly transmitting to multiple clients such
as remote interfaces or management software. 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. This division of labor greatly
enhances scalability. As the overall system size grows, the CPU
resources and bandwidth requirements of the edge gateway remain
In addition, MQTT is a lightweight protocol. Common broker
implementations consume only about 3 MB of RAM with 1,000 connected
clients. This small footprint means the HMI can be configured as
both an edge gateway and as an MQTT broker, reducing the need for
Applications engineers have a lot of flexibility using the data an
edge gateway produces as an MQTT publisher. Engineers can assign
topic names to the variables or tags they wish to publish to the
broker. Topics provide the structure for organizing data in the MQTT
protocol. MQTT allows topics to be divided in intuitive ways. A
single data point can be assigned to multiple topics, and one topic
can contain more than one data point. An application can subscribe
to all topics from a single HMI, creating an application monitoring
all data from one specific machine. Or, if a parameter (say
temperature) exists on many machines, the programmer can use a topic
“wild card” to instantly subscribe to the same parameter across all
machines. This enables efficient and easy detection of abnormal
conditions across an entire installed base of machines.
The HMI configuration process is easy for the controls engineer who
incorporates an edge gateway into a system. The engineer simply
creates an authenticated broker connection, then selects the tags to
publish. The engineer organizes tags into topics, then downloads the
project to the HMI.
MQTT is one of many Internet-enabled applications available on edge
gateway devices, such as Maple HMIs, which offer many notable
communication and data collection features. HMIs can send emails
containing data logs and alarm conditions. Remote access
applications let remote users monitor and control machines through
secure VPN connections. They also enable remote download of project
updates. Database integration allows machines to log data directly
to database servers over an Internet connection (LANWAN). The cMT
Viewer and HMI Viewer applications enable Android and Apple tablets
and smartphones to monitor and control your HMI. Compared to a full
machine replacement, our edge gateway-enabled HMIs are an
inexpensive option for upgrading machines or adding to new machine
Here’s an example of how the configuration process typically works.
Company A wants to offer customers remote access/monitoring, remote
email alarms, off-site troubleshooting and configuration, and
similar benefits. Company A goes with the MQTT protocol for its
extensive use, excellent documentation, cloud compatibility, and
ability to efficiently transport large amounts of data across
networks. MQTT also allows Company A to seamlessly expand its Amazon
Web Services functionality without hogging all available network
bandwidth at each manufacturing site.
The company’s engineering departments use many different PLC brands,
all with different protocols. So, Company A decides to use a Maple
Systems Dual-Ethernet HMI, which serves as both an HMI and edge
gateway. The HMI supports MQTT and more than 350 other control
protocols, letting it link existing control networks with the IIoT.
Dual-Ethernet ports separate networks inside the plant from external
information technology networks. This secure connection allows for
advanced remote access and monitoring, remote email alarms and
remote programming. Dual-Ethernet HMIs let Company A maintain an
isolated network dedicated to its machinery, yet still offer access
to the internet through the customer’s ISP. The publish/subscribe
architecture of the MQTT network means Company A personnel won’t
have to issue any change requests to their customers’ IT
Because their systems are widely distributed, Company A hosts its
MQTT broker off-site. The new data stream connects to a web
application that customers can log into for real-time machine
Remote functions built into the HMI allow Company A to update
projects (including performing off-site MQTT setup) to meet changing
customer demands without spending time and money on-site. It can
respond faster to software and data demands across deployed
equipment. Company A uses predictive maintenance instead of
preventative maintenance to cut costs, improve troubleshooting and
reduce downtime. New machines added to the network send smart data
back to the central database for analysis.
Consider another example involving a single-facility food processing
company. Like many in the manufacturing industry, Company B’s
biggest obstacles for IIoT adoption are budget and interoperability.
Its factory hosts both Ethernet and serial control networks unable
to share data because of incompatible protocols. The company wants
to centralize data without buying a new server and remote hosting.
Key requirements for IIoT hardware include support for the MQTT
protocol, legacy protocol support and secure remote access. A Maple
Systems Headless HMI fits Company B’s needs because there’s no
requirement for new displays. This unit has a small form factor that
fits into existing panels.
Company B creates both a project and the MQTT broker inside its new
interfaces using EBPro configuration software. They define MQTT
topics to bring data from the plant floor to dashboards and
analytics programs in use by management. Analytics software can now
offer a live data stream from operating machinery.
Remote access for the Headless HMI securely connects over a VPN to
laptops, Android and Apple smartphones or tablets, giving floor
managers mobile access. The email alarm feature alerts staff
immediately when something runs amiss regardless of location.
Dual-Ethernet ports plus serial communication offers a safe
connection to office networks exposed to the Internet.
The centralization of data from facility machinery boosts overall
system awareness. Maintenance costs drop thanks to the linking of
data about machine wear and usage. Software identifies data patterns
that indicate likely failures, so machines can run to full life
without risking costly shutdowns.
All in all, Company B
can derive new insights using detailed statistics on both its
highest-profit machines and on its process bottlenecks. The Maple
Systems HMI edge gateway performs local machine control while
opening these new possibilities in the IIoT.
⇐ Back To IIoT Solutions
Please Sign in or Register to continue reading this article.