Patrick Bunn, owner of Bunn Automation Consulting, has been a long-time contributor to Control Design. Based in Birmingham, Alabama, Bunn has previously shared his skills and expertise with CMC Steel Alabama, Revere Control Systems, EC&S, Hargrove Controls & Automation and Enercon. Additionally, he's also done volunteer work with younger people in technology, engineering and automation.

His first Control Design contributed article, published in March 2025, explained the seven layers of the OSI model, as well as the standards and protocols relevant to industrial control systems. Understanding the OSI model has been able help control engineers troubleshoot network issues and optimize industrial communication systems.

His next article, published in March 2026, shared who is responsible for defining acceptance criteria for factory acceptance testing (FAT) and site acceptance testing (SAT). According to Bunn, without a shared baseline for "correct" behavior, FAT and SAT often only prove a system was built and wired correctly, rather than verifying it actually works as the process requires.

"When the owner does not define acceptance criteria, the responsibility implicitly shifts to the contractor," Bunn wrote in the article. "And contractors, rationally, will define acceptance in a way that minimizes their risk exposure, not necessarily in a way that ensures operational success for the end user. That is the core issue."

In addition to contributing articles for Control Design's readers, he's also been a guest on the Control Intelligence podcast and joined us on our YouTube channel.

In this three-part video series, Bunn discussed his history as a controls engineer, the differences between programmable logic controllers and distributed control systems and how to best upgrade older control systems, plus much more.