The Purdue Reference Model is a reference data flow model for computer-integrated manufacturing (CIM), or using computers to control the entire production process. It is a component of the Purdue Enterprise Reference Architecture (PERA). Enterprises can use the Purdue Reference Model, “95,” which offers a model where end users, integrators, and vendors can work together to integrate applications at crucial layers of the network and process infrastructure of the company.
Introduction to the Purdue Enterprise Reference Architecture
The Purdue Model was developed at Purdue University in the early 1990s with the aim of defining best practices for the interaction between industrial control systems and business networks (Alternatively, to use the words interchangeably, OT and IT). There were three parts in the first version:
- Enterprise Reference Architecture for Purdue
- Reference Model for Purdue
- Manual of Purdue Implementation Procedures
The six network layers of the environment were included in the model over time, along with guidelines for physical systems architecture, and each level’s systems and technologies are shown.
Level 4/5 - Enterprise:
The main business operations normally take place on this level of the IT network as we know it today. This level coordinates production activities and offers company direction. The production schedules, material usage, shipping, and inventory levels in a facility are all controlled by enterprise resource planning (ERP) systems. Offerings from Oracle, SAP, Microsoft, and Epicor are among the most widely used ERP systems. Any interruptions at this level have the potential to cause days or even weeks of downtime and result in severe revenue loss by delaying or stopping downstream activities.
Level 3.5 - Demilitarized zone (DMZ):
This level, which has only been added in the last ten years, includes security solutions like firewalls and proxies that are meant to divide or create an air gap between the OT and IT sectors. The “convergence” of the IT and OT sectors at this point broadens the attack surface for OT systems. This layer is absent from many plants or its capabilities are extremely constrained. The necessity for bidirectional data flows between OT and IT systems has increased due to the advent of automation and improved efficiency. For businesses that are speeding their digital transformation, this OT-IT convergence is ultimately generating a significant competitive advantage.
Level 3 – Manufacturing operations systems:
The factory floor, here is where the production workflow is managed. To control operations and plant performance, collect data, and perform batch management, customised systems based on operating systems like Windows are employed. These systems are referred to as manufacturing operations management systems (MOMS) or manufacturing execution systems (MES). MES/MOMS are particular to the goods being produced/processed. Databases or historians are also included in this tier to store the operational data. A dedicated backhaul network to the main data center or headquarters is often used for communication between the enterprise level and production level. Any interruptions at the production level, like those at the enterprise level, can cause hours or days of downtime and have a significant influence on the entire manufacturing plant’s ability to generate income.
Level 2 – Control systems:
Software for supervisory control and data acquisition, or SCADA, is used to oversee, track, and manage physical processes. The distributed control system (DCS) and programmable logic controllers (PLCs) are often implemented inside the plant, whereas SCADA may manage systems over great distances from the actual location of the facilities. Basic controls and monitoring are possible through the human-machine interface (HMI) coupled with DCS and PLCs, while SCADA systems collect data and send it upstream for level 3 history historians to record. These control system-oriented machines will be connected at this level. . Data diodes like Modbus firewalls can support security at this layer, for devices and strategies commonly communicate through the Modbus and dnp3 protocols.
Level 1 - Intelligent devices:
DCS/PLC Controllers, RTUs, Process sensors, analyzers, actuators, and associated equipment are used at this level to sense and control physical processes. In order to increase efficiency, sensors are increasingly using cellular networks to communicate directly with the vendor monitoring software.
(Level 0)Physical process:
Describes the real physical processes.