Ethernet at the factory-floor level was a hotly debated topic in the late 1990s, but many companies sidestepped arguing in favor of doing. In the process, they are proving that Ethernet can yield financial rewards for manufacturing.

One example is a chemical plant where engineers use high-speed Ethernet with Foundation Fieldbus to provide all the functions required by the project without the cost of additional controllers. A discrete parts manufacturing plant needed to automate online testing and communicate real-time product data. Ethernet comes to the rescue, again. When a parts supplier to Jaguar required the speed and coordination of a, well, Jaguar, an Ethernet vision network helped assure quality and parts coordination with the assembly plant. Retrofitting old die cast machines proved to be a challenge met with Ethernet control networks hosted on programmable logic controllers (PLCs). And, when a heavy vehicle manufacturer wanted to build its “plant of the future,” wireless Ethernet I/O devices saved the day.

A 1940s vintage plant, Merisol’s Greens Bayou cresylic acid production facility, located near Houston, Texas, includes process units that upgrade and refine phenol, cresols and xylenols—products used in the manufacture of resins, solvents, antioxidants, functional fluids, cosmetics, disinfectants, agricultural chemicals and many other chemical intermediates.

Engineers and managers wanted to modernize Merisol’s process automation systems while improving plant-wide data access. Legacy Honeywell TDC 2000 and older Moore distributed control systems (DCSs) were slated for replacement with PLCs, with the goal of an integrated system providing full access to process information and displays from any plant location.

Henry Marks of Henry Marks Associates was hired to provide detailed engineering for the first two phases of the project, and to serve as project manager for the first phase. Marks was product manager for the TDC 2000 DCS at Honeywell when it was developed in the 1970s. He was also product manager for the next two generations of the product line. Marks says he became really interested in Foundation Fieldbus when the wraps came off the Foundation Fieldbus high-speed Ethernet (FF-HSE) protocol at the ISA Show in 1999. He knew that would be the perfect fit for this project.

Marks continues, “Merisol’s Brad Bonnet was the real pusher for the project. A former control engineer, he was now with the information technology operation and provided the needed communications infrastructure. He had already implemented plant-wide Ethernet systems, so I knew as soon as I saw FF-HSE that we could superimpose it on that network, providing a whole new dimension to the architecture.”

The existing TDC 2000 and Moore DCS didn’t talk to anything, according to Marks, so the engineers had already begun implementation of a GE Fanuc PLC in part of the plant. Their intention was to install a control network of FF-HSE so that they could install operator displays in various locations using Wonderware HMI, a human-machine interface system. Marks decided to build upon this architecture to implement an entirely different control scheme.

Rather than buy more PLCs, he decided to accomplish control with intelligent positioners on control valves in the field, leveraging the promised interoperability of built-in Foundation Fieldbus. He explains, “This interoperability is supposed to be the greatest thing, so we did just that—mingling products from Rosemount, Yamatake and several more. Because this was the first implementation of FF-HSE, we were the ones who identified the interoperability that wasn’t all that great and helped correct it. Even though that slowed us down, we still got the project done. FF-HSE plus OPC [Object Linking and Embedding for process control] can communicate with just about anything. One of the first things we did when it was all connected was to expand the Wonderware installation for redundant Microsoft SQL database so that reports were not only meaningful but were available to all who needed the information, while still maintaining the firewall.”

This project required close coordination between Marks and other engineers and Bonnet and the IT department. Was this a culture clash leading to acrimony and delays? Marks replies, “Bonnet had been in charge of control systems, then moved to IT. Plus it wasn’t a big plant so there were no empires involved. Now you have the support of the IT people since with FF-HSE, they don’t have to get on their knees to beg help from control. Although the Fieldbus Foundation started with an independent protocol, it decided to maintain standard high-speed Ethernet media. This simplified the architecture and built support in IT and management.”

Marks states that with the new devices and parameters available, ...