Five Critical Factors in Industrial Control System Integration

Ali Awais Amin

Control system integration is fundamental to industrial automation. Automation professionals with even a rudimentary knowledge of system integration realize and understand that isolation is coming to an end. In fact, control system integrators provide maximum value to the client by designing the system called for by the project parameters rather than having to tailor a particular proprietary system according to the specific requirements.

There are five factors involved in integrating different control systems:

1. Software infrastructure
2. Process databases  
3. Operator interface
4. Alarm management
5. Network security.

Each has a vital role to play. Here is an in-depth look at each one:

1. Software infrastructure: A modern automation system needs more than just configuration and monitoring functions. Applications also must be integrated, which is why software infrastructure is important for system integration. In an open software architecture employing a client-server scheme, the client application displays data from a server application.

Developed by the OPC Foundation, the OLE for process control-unified architecture (OPC-UA) technology is designed to provide simpler browsing and real-time and historical data exchange. OPC-UA provides integrators more flexibility to integrate different systems in a desired configuration instead of being locked into a specific setup by proprietary technology. The standard's focus is interoperability and is designed to connect many devices to create a bridge from legacy products to new devices. 

2. Process database: Database components primarily include three main components: one or more tables for the data, a query language (e.g., SQL), and forms for displaying or entering data. Additional components include customized page views of data and reporting tools. Moreover, a relational database is a collection of data items. These data items are organized as a set of formally described tables from which data can be accessed in many ways without the need to reorganize the database tables.

A database management system (DBMS) collects interrelated files and programs, which allow users to access and modify files. This is an efficient way to modify, store, and retrieve information. A query language such as SQL is used to interact with DBMS. 

3. Human-machine interface: The human-machine interface (HMI) allows operators to monitor the state of a control process and issue commands to change the control objective. In emergency situations, it can also be used to manually override automatic controls. The primary aspects of HMI configuration are graphics, historical trend, alarms, reports, and scripts. These capabilities may either be merged into a single software application or made available as individual components in a suite. 

4. Alarm management: Alarms mark the boundary between normal and abnormal conditions in the process and serve as the primary means of alerting operators of abnormal situations in their facilities. Plant operation requires alarms to be prioritized, relevant, and timely to be effective. Alarm management is critical when integrating different control systems and so alarm systems need to be designed to help identify critical issues. 

5. Network security: Integrated control and safety systems (ICSS) operate within a complex environment with organizations increasingly sharing information between business systems and industrial systems. In addition to this, industrial systems, which include process control systems, safety systems, and programmable logic controllers (PLCs) have relied on commercial, off-the-shelf (COTS) technologies such as Ethernet, TCP/IP and Microsoft Windows for critical and noncritical functions. However, the isolation from the outside world is significantly less. In fact, in an event of security breach, the potential loss of life or production, environmental damage, and compromise to operational safety are far more serious consequences than loss of trade secrets. 

These may have ramifications beyond the targeted organization and may also damage the infrastructure of the host region or nation. 

A detailed cybersecurity analysis and cyber risk assessment are required. They should include detailed specifications, policies and procedures for OS patch management, antivirus implementation, and backup and restore procedures. 

Automation does not merely comprise of equipment control. It includes higher levels of control that manage personnel, materials, and equipment across all factory production areas. This usually is accomplished using the documented procedures and software collectively known as the manufacturing execution system (MES) layer. MES is a control system for managing and monitoring important tasks in a plant. It supports the planning and control all the way to finished product, which brings transparency to the highly complex production tasks. 

Four categories of enterprise and control systems are defined by the ISA-95 depending on their roles. These categories are organized in a hierarchical model in which activities associated to each category are specified. The image below illustrates the ISA-95 Functional Hierarchy Model.

Level 0 defines the actual physical processes. 

Level 1 defines the activities involved in sensing and manipulating the physical processes. 

Level 2 defines the activities of monitoring and controlling the physical processes. These systems are typically implemented on PLCs and distributed control systems (DCSs). 

Level 3 activities are usually automated using MES, which also acts as the interface layer between the control layer (Level 2) and the enterprise resource planning (ERP) layer (Level 4).

Level 4 defines business-related activities that manage a manufacturing organization and is called Business Planning and Logistics. Level 4 activities are automated using ERP systems.