Whatever the differences in their applications, situation or locations, all industrial networks need a few common things to survive and function. So just as people require air, water, food, shelter, healthcare, education for the kids and the local equivalent of Monday Night Football, all industrial networks need wire and cable, connectors, switches, power, signal conditioning, communication protocols, and support and monitoring software to make sure all their elements are running properly.
None of these needs are very difficult to fulfill. All they require is a little awareness and the initiative to go out and get them. Unfortunately, despite their many common needs, industrial networks have grown up quickly in all kinds of different applications and industries, so knowledge of their basic needs and providing for them is often lacking. Thankfully, many new methods and tools, usually from veteran, IT-based networks and their users, are showing up to help their industrial counterparts.
Can't find the problem
Israel-based N.R. Spuntech Industries manufactures non-woven, hydro-entangled, Spunlace fabric used in the medical, construction, agricultural and consumer products industries. The production line at its new, 20,000-m2 plant in Roxboro, N.C., runs seven PLCs and about 350 nodes on a Profibus network. The line can turn any combination of raw cotton, cotton, viscose, polyester or polypropylene fibers into rolls of finished fabrics via a complex and tightly monitored series of operations, including opening, cording, drying and packaging.
Though the facility was new, the production line's network began experiencing random and sporadic instances of nodes dropping on and off. "Each occurrence cut the lines of communication between the line's monitoring station and critical pieces of equipment, leaving us without eyes or ears on the production floor," says Paul Hall, process control and IT manager at the Roxboro plant. "Because of these intermittent issues, we were forced to stop the production line multiple times, sometimes for hours. The resulting costs in lost revenue were substantial."
Hall was further frustrated that these interruptions in the network's communications happened without warning, without any pattern and often self-corrected without providing any clues as to what triggered them. "We were unable to physically or programmatically determine the root of the problem, and so we had to approach each new day ready for anything," Hall says. "This unresolved problem felt like a ticking time bomb and caused us a lot of stress."
Get inside, look around
To cure his sick network, Hall researched various monitoring and diagnostic solutions that could provide accessible and in-depth visibility into its performance and eventually selected Th Link central network access point components and Th Scope diagnostic software from Trebing + Himstedt. Th Link provided immediate OPC compatibility, which allowed Hall to tie the new access points directly to his existing SCADA system and monitor the real-time health of his network (Figure 1). It also enabled his operators and technicians to centralize their activities on one system instead of jumping from PC to PC to monitor and diagnose network issues.
Within the first week of adding Th Link and Th Scope to the Roxboro plant's network, Hall used it to monitor the next network interruption when it occurred, and identified and isolated a particular unit on the production line that caused the chronic node dropouts and downtime. "When this problem occurred before, we could only guess at the cause," Hall explains.