DMC was approached by Natoli to help improve the reliability and maintainability of the controls software for an existing product line. DMC collaborated with Natoli's controls engineers to identify key points of instability and encapsulate what is expected to vary into the future. What we found was an organizational structure often seen in systems that have been developed by several engineers over the course of many years. The software accomplished each individual goal of the system independently. Yet, due to this the lack of encapsulation, adding new features created bugs - sometimes in unrelated, previously tested functionality.
DMC was a good match for this project. We have extensive experience refactoring machine-level control for OEM machine builders across many industries (packaging, frozen food, automotive). A “state machine" model provided a solid foundation for the execution of individual subsystems. While this press is not a piece of packaging machinery, the PackML state model (based on ISA TR88) is time tested, familiar to those integrating machinery into production lines, and available as a piece of reusable code in the Rockwell Application Code Manager.
Without modifying validated code, DMC was able to integrate the PackML state machine's structure into the PLC program. This program structure has been easier to modify, commission, and service. Furthermore, the PackML state machine makes higher-level line-control exceptionally easy to integrate, as many line-level or supervisory systems contain integration templates for PackML-compliant machines.
Learn more about DMC's Allen-Bradley PLC expertise.