In its own way, every project in a manufacturing plant covers the collection of data from machines, sensors and RFID readers or the exchange of data between OT systems and higher-level IT applications. OPC servers are often deployed, and data is transferred via the OPC UA protocol.
Nevertheless, OPC UA is only one of several options. Among the widely used lightweight, simple solutions for data transfer, you will also find the MQTT protocol.
MQTT is a popular protocol for sending messages and exchanging data and is based on the publisher/subscriber communication model. In this model, there is one central system – the MQTT broker – that the clients connected to it exchange messages through. Clients can send data to the MQTT broker (acting as publishers) and/or receive it from the broker (acting as subscribers).
Introduced in 1999, MQTT has been here for quite some time. It was first used to monitor oil pipelines within the SCADA industrial control system. The goal of its developers, the companies IBM and Cirrus Link, was to have a bandwidth-efficient, lightweight protocol that would use little battery power. The devices on the pipelines were connected via a satellite link which, at that time, was extremely expensive.