Evaluation of Industrial Controllers’ Connectivity using MQTT Message Protocol

The increase of the Industrial Internet of Things (IIoT) and Industry 4.0 led to many interconnections in the control systems. IIoT has begun its evolution and development in the scientific community and industrial application field. As communication between IIoT devices and other equipment needs to be implemented through the network, it is necessary to provide reliable and straightforward data transmission. This thesis investigates how to develop a middleware that provides connectivity between specific industrial environments. Particularly, a prototype design is created to connect an industrial controller with information of interest using the Message Queuing Telemetry Transport (MQTT) protocol. We set up experiments to evaluate the features of the implemented prototype. The experiment examines the effect of the developed prototype's end-to-end response time and scalability characteristics by receiving a different number of messages from the stimulator. By measuring the end-to-end response time, the experiment showed that in the case of many input/output (I/O) signals arriving in the connectivity service, the implemented prototype is well scaled under examined circumstances. Observing the results, the middleware prototype gave acceptable results in terms of response time. Also, it gave us a picture of how different network settings can cause a difference in estimating the end-to-end response time of a message