One of the most common ways to represent the architecture of an industrial plant is as a pyramid.
At the base of the pyramid is the level of sensors and actuators, forming what we call Instrumentation or Level 0. Above that level are the programmable control systems, such as PLCs and DCSs, which are collectively known as Level 1. These, in turn, involve operators through HMI or SCADA systems, which can have their own scripts, that is for a particular line, for example, for the managing recipes or calculating setpoints.
At the top of the pyramid are the decision systems of the company, also known as Business Intelligence, such as MES. These allow the examination of a company’s behavior at the management level using metrics and operation systems known generically as ERP, that track activities such as invoicing, inventory management, purchasing, human resources and other functions.