Summary

In this chapter, we analyzed the main devices involved in the I-IoT data flow in an industrial plant in detail. We started from the generation of the data, looking at how physical measurements are captured by the transducers, converted to a digital signal, and passed through the industrial networks by controllers. We learned that industrial networks provide determinism in message delivery, which is a fundamental requisite in the control process. We discovered the enabling mechanisms that can guarantee deterministic networks. We compared a simplified networking model (an EPA) with the full model of the ISO/OSI stack and we looked at the methods that are used to access the physical link of the control network to ensure that the packet is transmitted within a determined time interval. We also learned that there are different types of industrial networks according to the length of the message and the complexity of the industrial device.

After that, we analyzed controllers in detail, looking specifically at microcontrollers, PLCs, and DCSs. We explained their main characteristics, how they differ from one another, and which industrial scenarios they each cover. We learned that they all get their measurements from the sensors as an input, they perform control algorithms, and they provide the values for the actuators, acting on the physical process as an output.

We then moved our discussion to a higher level, that is, analyzing the SCADA system and Historian. We looked at the main features of a SCADA system and the main mechanisms that allow a Historian to collect, store, and retrieve a huge amount of time series data. We learned a wide range of key terms, including tags and tag names, time series, sampling, polling and unsolicited, store and forward, data filtering, and data compression. Finally, we outlined the ERP system and explained what a MES system is. We also looked at the asset model, as it plays a key role in managing industrial data.

In the next chapter, we will learn more about the OPC and the edge device, looking closer at how the OPC allows data to pass to the edge. We will then analyze the edge and follow the I-IoT data flow until it reaches its destination in the cloud.