In this chapter, we'll take a close look at the equipment, devices, protocols, and software layers that manage industrial data along its path in the factory. We'll start from the sensors and track the path of data until we reach the edge, which is the external boundary of the I-IoT data flow inside the factory. We'll look at how industrial signals are generated and how they are managed, exchanged, and enriched by passing through the different levels of the CIM pyramid. We'll also consider what the main OT devices that are involved in each level are. The reader will learn about analog to digital conversion and vice versa, sensors and actuators, remote terminal units (RTU), embedded controllers, programmable logic controllers (PLCs), distributed control system (DCS), Supervisory Control and Data Acquisition (SCADA), Historian, industrial protocols, and fieldbus. We would require a specific chapter for each system in order to explain them exhaustively, so instead we will focus on analyzing them in this chapter from the point of view of the I-IoT data flow. We'll briefly highlight their main mechanisms, but we'll explain in detail how they are important and relevant from the perspective of data acquisition and collection. Acquiring industrial data from sensors and controllers is one of the most critical processes in I-IoT and comes with its own specific challenges and constraints to overcome.

In this chapter, we will cover the following topics:

• The I-IoT data flow in the factory
• The measurement and actuator chain
• Controllers
• Industrial protocols
• SCADA
• Historian
• Enterprise Resource Planning (ERP) and the Manufacturing Execution System (MES)