Wood processing companies increasingly use high technology equipment to process wood products.
The problem for system integrators, though, is reconciling disparate control systems.

Fulghum Industries, Inc. provides heavy-duty industrial machinery to the forest products industry. It often implements remote wood processing facilities (woodyards) adjacent to pulp and paper mills, and so must integrate its equipment into sophisticated wood handling machinery that has its own embedded control systems. This machinery includes stacker-reclaimers manufactured by Bruks® Rockwood LLC which recover and stack woodchips into stockpiles of up to 6 million cubic feet.

Packaging Corporation of America manufactures about 2.4 million tons of containerboard and 31.2 billion square feet of corrugated products annually. The Rockwood stacker-reclaimer located at the PCA facility in Valdosta, GA includes an Allen-Bradley control system that communicates through the EtherNet/IP protocol.

The reclaimer’s design is similar to that of a giant chainsaw, with a massive boom that rotates and then rakes woodchips back from the stockpile to load onto conveyors. This 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.

Birmingham, Alabama-based systems integrator Electric Machine Control was contracted to program the reclaimer’s Allen-Bradley control system. Fulghum is responsible for the other equipment, including the log handling cranes, debarkers, and conveying systems, which use different control systems, including Opto 22’s SNAP PAC System™.

The SNAP PAC System controls the conveying systems that handle materials from the woodyard chipper and debarker, as well as from two truck dumps. It also monitors chipper motors’ amperage, temperature, oil pressure, and other conditions.

Improving operations where critical control processes are handled by hardware from multiple vendors proved challenging for Fulghum and its integrator partner, Advanced Control Solutions. Engineers at the two companies preferred the SNAP PAC System. The stacker-reclaimer, meanwhile, remained dependent on its embedded A-B control system. As the woodyard expanded, Fulghum, ACS, and Electric Machine Control found themselves having to respond to new control system performance requirements. As processes were added and others modified, newly added equipment and instrumentation needed to be switched, and operating conditions and equipment states needed to be closely monitored. In some cases, alarms needed to be established to warn when conditions (or machine performance) deviated out of specifications.

System integration engineers were able to integrate Opto22 SNAP PAC systems with Allen-Bradley control systems in this woodyard application.

Systems Engineer Sean O’Rourke from ACS implemented and configured SNAP analog and digital I/O and controllers to add the needed functions. Electric Machine Control customized and fine-tuned changes to the Allen-Bradley ControlLogix® PLC and control programs. It was imperative to find a way for these two systems to communicate and share information. It was determined that the best way to accomplish this would be to maintain the local Opto 22 distributed system while using the plant-wide Ethernet TCP/IP network. 

The SNAP PAC System supports EtherNet/IP which allows SNAP controllers to serve as a slave device and integrate seamlessly with the Contol Logix hardware. O’Rourke worked with the Electrtric Machine Control to connect to the Allen-Bradley PLCs through fiber optic connections.

“Configuration and setup was simple,” O’Rourke says. “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.”

The configuration was then downloaded to the 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.”

Opto 22
www.opto22.com