Designed to be light weight, open, and simple, MQTT is a subscriber/publisher messaging transport protocol that is considered a great solution for applications where a small code footprint is required and/or network bandwidth is scarce. It is particularly suitable for continuous monitoring of sensory data such as temperature, pressure, water level, energy monitoring, etc.
Learn more about MQTT
MQTT stands for Message Queuing Telemetry Transport. It is an extremely simple and lightweight publish/subscribe messaging protocol, designed for constrained devices and low-bandwidth, high-latency, or unreliable networks. The design principles are to minimize network bandwidth and device resource requirements while also attempting to ensure reliability and some degree of assurance of delivery. These principles make the protocol ideal for the emerging "machine-to-machine" (M2M) or "Industrial Internet of Things" (IIoT) world of connected devices and for remote applications where network connectivity and bandwidth are at a premium. It was first developed by IBM in 1999 and is now an open standard that has become widely implemented across a variety of industries.
The MQTT protocol allows your system to access IIoT data. MQTT brings many powerful benefits to your process:
To fully realize benefits of the IIoT, data transmitted by the HMI or "edge gateway" must be presented to upstream IT applications in a way that is flexible, modular, and efficient. The MQTT feature available on all Maple Systems HMI products exemplifies the power of this protocol. MQTT is organized into topics which can contain single data points or a group of related data. Topic names are assigned to the variables or tags they wish to publish to the broker. Topics are the titles, or addresses, used to organize data in MQTT protocol. 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.
MQTT allows topics to be broken down 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 on a single HMI, creating an application monitoring one specific machine. Or, if a parameter, say temperature, exists on many machines, the programmer can use a topic "wild card" enabling them 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 publish-subscribe messaging pattern requires a message broker. The publisher/subscriber model allows MQTT clients to communicate one-to-one, one-to-many and many-to-one. Our Advanced and cMT products support all three functions of the MQTT protocol, enabling them to communicate with a wide array of PLCs, sensors, and more, regardless of the machine's protocol.
With support for over 300+ PLC and controller protocols, Maple HMIs convert that data into the universally accepted MQTT protocol, then send it to a broker (hosted locally or in the cloud) for use by IIoT applications. This makes Maple Systems HMIs the perfect edge gateway to the IIoT.
For the controls engineer looking to incorporate an edge gateway into their system, the HMI configuration process in EBPro could not be easier: simply create an authenticated broker connection, then select the tags you wish to publish.
Point and click to organize tags into topics for your specific application, download the project to the HMI, and you're up and running.
Download and follow our cMT/HMI MQTT User Manual to get started. Read how to step up MQTT, create topics, choose a broker, and subscribe to topics. Additional features covered are AWS IoT and Sparkplug B.
2. MQTT Set-Up Tech Note and Sample Project
Along with a MQTT Set-Up Sample project, Tech Note 5111, MQTT Set-up walks through the steps necessary to configure an HMI as an edge gateway for an MQTT network and demonstrates how to use the HMI as an Edge Gateway.
Publisher– A Publisher is a sensor, PLCs, HMI, or anything creating data. Sometimes called a "Server" or "Edge Device". The publisher sends a message to a central topic (broker) which has multiple subscribers waiting to receive the message.
Broker- An MQTT broker is a server that receives all messages from the clients and then routes the messages to the appropriate destination subscribers/client
Subscriber/Client- The end user of the data. This can range from a high-end ERP management program that tracks information for control and data analytics, to a website that simply displays real-time operational facility data, and anything in between. The subscriber/client specifies one or more topics on the MQTT broker that they