Control system retrofits — The network is key

With a quick glance through this paper the reader will question if it is being presented at the correct conference. The paper is full of IT jargon and networking concepts that would likely be more at home in an IT conference. That is exactly the point of the paper. Plant Control Systems are being tasked with handling increasing amounts of information from intelligent devices and subsystems in the field. In order to accomplish this, the plant network components are using Ethernet networks in increasingly complex forms. Ethernet can provide flexible and high speed data communications throughout the plant but can also provide major disruptions if the network is not both physically and functionally designed properly. Further, Ethernet networks require specialized knowledge and tools in order to monitor performance and troubleshoot problems. This paper begins with a control system upgrade at a Texas cement plant, provides a brief historical overview of legacy plant networks and tracks the migration to Ethernet. Important Ethernet concepts are defined and applied to highlight key network design and troubleshooting considerations in modern plant control networks. The paper is primarily written around a generic PLC-HMI control system model, but most terms, concepts and recommendations apply to most control systems found in cement plants today.