MAKING SENSE OF INDUSTRIAL NETWORKS

At the New Freedom wastewater plant, a fiber-optic ring connects these redundant RFC 460R controllers and the Profinet Media Redundancy Protocol provides millisecond fault recovery time.

hundreds of automation vendors. This includes programmable logic controllers (PLCs), programmable automation controllers (PACs), drives, robots, input-output devices (I/Os), and diagnostic tools.

At Milstead Farm, Profinet was initially installed as part of an upgrade project aimed at fine-tuning the company’s process controls and adding some new moisture-control equipment to help the humidifier keep pace with rising production levels. The company was already using Profibus for its plant floor fieldbus communications. The upgrade included replacing an obsolete PLC with a more powerful one and changing a local I/O rack at the end of the 2017 ginning season. At the end of the following season, Profinet was installed to network the two controllers in the plant.

Profinet also prepares Milstead Farm’s gin for the future. Although the existing Profibus network was still performing quite well, it was approaching its design limits in terms of node counts and cable distance, according to David Adams, the systems integrator at Design Automated Controls who performed the upgrade.

Besides extending these limits, Profinet also increased data transfer rates and integrated easily with the company’s existing Profibus network. The new central processing unit (CPU) has Profibus and Profinet onboard, so it permits the machinery still using the Profibus protocol to communicate seamlessly with the control system.

Perhaps just as important is the path that Profinet opens for future upgrades. Among the first upgrades Milstead Farms has planned are the new Ethernet-based human-machine interfaces (HMIs) to replace the five aging HMIs on the Profibus network. The new HMIs will provide Milstead Farms with more—and better— troubleshooting tools.

Building on the past to create the future

In a way, the migration toward Profinet at Milstead Farm reflects the lessons learned from its predecessor, the Profibus fieldbus. “The experiences gained from building Profibus during the 1990s helped immensely when the time came to introduce Profinet in the early 2000s,” explains Michael Bowne, executive director, Profibus and Profinet International (PI) North America.

His reasoning is that a fully functional fieldbus does more than simply transfer bits and bytes among devices on the factory floor. It also