MQTT, or Message Queue Telemetry Transport, is a publish/subscribe messaging protocol that was originally created for resource-constrained devices over low-bandwidth networks. It is useful as an IoT protocol because it has a small footprint, is reasonably simple to use, and features “push” architecture which can solve problems with a typical Master – Slave polled response model and is inherently more secure.
MQTT allows our HMI/PLC to connect to a server called a “broker”, and publish their data to it. Any device or program that wants to receive the data can subscribe to that channel on the Broker. The broker does not examine the data payload itself, but simply passes it as a message from each publisher to all subscribers which allows the use of low bandwidth networks.
The publish/subscribe approach has advantages for general IoT applications. “Push” architecture is inherently more secure, because it avoids the client-server (Master Slave) architecture problem, allowing devices to make outbound connections without opening any firewall ports. And, by using a central broker, it is possible to establish many-to-many connections, allowing multiple devices to connect to multiple clients.
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The Horner name is synonymous with automation controllers with a built-in operator interface and I/O, but now Horner Automation also provides software that allows customers to remotely monitor and control machines.