Reconciling disparate control systems, each very powerful and having individual strengths, is becoming quite common for systems' integrators, especially as end users look for options to modify and improve their control systems.
For Fulghum Industries Inc., one of the first companies to implement remote wood processing facilities adjacent to paper mills, the challenge was creating an interconnection between a stacker-reclaimer and other conveying systems at the plant.
The stacker-reclaimer is located at the Packaging Corp. of America facility in Valdosta, GA and includes an Allen-Bradley control system which communicates via EtherNet/IP. The system, manufactured by Bruks Rockwood LLC, is basically a belt conveyor on a crane boom that builds a kidney-shaped pile.
"The reclaimer's design is similar to that of a giant chain saw, with a massive boom that rotates and rakes woodchips back from the stockpile to load onto conveyors," says John Lewis, Fulghum's vice president of engineering and construction. The machinery is outfitted with variable frequency drives (VFDs) regulated by Allen-Bradley controllers that, among other functions, speed up or slow down recovery of the wood chips.
Beyond the reclaimer, Fulghum also has responsibility for other equipment at the woodyard such as log handling cranes, debarkers and a variety of other conveying systems which utilize different control systems. Opto 22's SNAP PAC System(TM) is used for controlling conveying systems that handle materials from the woodyard chipper and debarker, as well as from two truck dumps.
Improving operations at the woodyard, with critical control processes handled by hardware from multiple vendors, proved to be a challenge for Fulghum and its integrator partner, Advanced Control Solutions. But a primary goal was to interconnect the two control systems for data throughput and operational coordination. Lewis says it was imperative to find a way for the two mismatched systems to not only coexist, but also communicate and share information utilizing the plant-wide Ethernet TCP/IP network.
Support for Allen-Bradley's EtherNet/IP protocol provided a method for the SNAP PAC System(TM) to communicate directly with the Allen-Bradley PLC. Once it is enabled, Opto 22 I/O can be added to Logix platforms and communicate with PLCs with no programming required.
ACS worked with integrator Electric Machine Control to interface to the Allen-Bradley PLCs via fiber-optic connections that provided a reliable, high bandwidth, long-distance physical medium with a high degree of noise immunity.
"Configuration and setup was simple," says Sean O'Rourke, a systems' engineer from ACS. "We only needed to define the assembly instances and assign inputs or outputs, then specify the number of bits for how long each instance was going to be."
This configuration was then downloaded to the Opto 22 SNAP PAC, and all that remained was to configure the Allen-Bradley RSLogix software and define communication to the SNAP PAC as a "generic Ethernet module."
Fulghum is now considering working with customers to extend the reach and capabilities of EtherNet/IP communication. Many of these customers use the ControlLogix platform for process control within their facilities, and could find value in being able to aggregate and combine operational data relating to their manufacturing and processing equipment with information from the woodyard.