Design_World_-_Internet_of_Things_Handbook_April_2020

eeworldonline.com | designworldonline.com 4 • 2020 DESIGN WORLD — EE NETWORK 41

Figure 3: MQTT creates a secure, highly

scalable, many-to-many architecture

for industrial applications and IIoT.

device, and the broker will deliver them as they
occur. If a device goes offl ine, the broker also
delivers that notifi cation to any subscribers.
This publish-subscribe communication
model allows for reliable, many-to-many
communication with reduced network traffi c
overall, making MQTT the kind of scalable
infrastructure that plant engineers are looking for.
MQTT is also inherently more secure than
traditional protocols. With the MQTT broker as
the single node in charge of routing all traffi c,
data access rights for the entire network can be
managed in one location. And because MQTT
connections are established by the device client,
not the MQTT server, there is no need to create
fi rewall exceptions for inbound MQTT traffi c,
even from outside the company network. With

the addition of SSL/TLS encryption, MQTT

traffi c can be safely routed over public networks,

and in fact, is the standard for all the major

cloud IoT platforms, like Amazon Web Services,

IBM Cloud, and Microsoft Azure.

But it is the OEM who unlocks the full

potential of MQTT for end users, because

direct support for MQTT in fi eld devices and

equipment produces the simplest integration

experience.

GET ON THE BANDWAGON

Fortunately for manufacturers, MQTT was

designed for use with resource-constrained

devices, and as such, has a simple specifi cation

with a small in-memory footprint. Open source

reference implementations of MQTT and

Sparkplug B are available in many programming

languages through the Eclipse Paho and Tahu

projects, and can be incorporated into PCB

fi rmware without royalties.

For manufacturers that use a dedicated

gateway as a customer data interface,

there are also MQTT-enabled controllers

and I/O gateway options available (Figure

4). This approach can be used to combine

communication functions with real-time control

or visualization in one device, but it also has

the advantage of tailoring data processing

IoT TECHNICAL TIPS