Control Narratives: Bridging the Gap Between Technical Teams and Plant Operations

• Control narratives translate complex automation logic into accessible language that non-programmers can understand, serving as a shared reference point between operations staff, process engineers and technical teams throughout project lifecycles. 
• They help engineers identify inefficiencies and streamline processes before programming begins, ultimately reducing engineering hours and resources during testing phases. 
• The upfront investment in creating thorough control narratives pays dividends long-term through improved project clarity, smoother knowledge transfer during personnel changes, and fewer costly surprises compared to projects that lack proper documentation.

The success of industrial automation projects often hinges on clear communication between technical teams and plant stakeholders. A powerful yet sometimes overlooked tool in achieving this clarity is the control narrative, which outlines system functionality in plain language and serves as a foundation for design, programming and testing.

A control narrative, sometimes referred to as a functional specification, outlines how a control system is expected to operate. It translates logic and code into accessible language that even non-programmers can understand. Rather than requiring familiarity with ladder logic or function blocks, the narrative provides a concise, readable description of system behavior under various process conditions.

How to develop a strong control narrative

A well-crafted control narrative documents functionality and serves as a comprehensive reference point throughout the project lifecycle. Common components include:

• Cause-and-effect matrices that outline expected system responses. 
• Descriptions of interlocks and logic to explain why systems are programmed a certain way. 
• Input/output (I/O) information that links specific loops to field devices. 
• References to drawings, such as P&IDs, loop diagrams or HMI screen locations. 

The best narratives prioritize clarity and context. Using descriptive labels like “dilution pump” instead of tag names like “Pump P52” can make the document more intuitive. While the writing may include complex "and/or" logic, the goal is to maintain readability.

Control narratives are often treated as living documents and updated as the system evolves, then handed over to the plant team at project completion. It’s not enough to have a control narrative; its value depends on how thoroughly and clearly it’s written. 

When are control narratives most useful?

Control narratives are especially valuable in logic modifications and system migrations. Even when adjusting a small section of code, a narrative can help clarify what’s changing and why. 

Typically, narratives are developed early in the project. In a migration scenario, engineers begin by exporting and analyzing the existing code. From there, a narrative is written and then reviewed by the operations and engineering personnel to be used as a foundation for programming and factory acceptance testing (FAT). 

For greenfield installations or system additions, engineers collaborate with process teams to review P&IDs and consult instrumentation groups to confirm field I/O, which is synthesized into the control narrative. In many cases, plant teams prefer to focus documentation on the updated portion rather than retroactively covering the entire system, especially if no existing narrative is available.

Why control narratives matter

The value of a control narrative is often underestimated. It provides a shared understanding of how the system is designed to operate, which is essential for sites where project handoffs occur across different teams or personnel.  In some cases, engineers discover unused or outdated code during the narrative review process, leading to cleanup and simplification.

Control narratives also provide a benchmark for testing. Whether it’s a major migration or a small logic change, having a defined reference helps guide and validate FAT.

The end user’s perspective

Some project stakeholders are reluctant to include control narratives because of perceived upfront costs. Yet in practice, the long-term value, through improved clarity, efficiency and fewer costly surprises far outweighs the initial investment.

During a recent migration project for a manufacturing facility, a well-written narrative helped identify inefficiencies and streamline several process steps before programming even began. As a result, the plant team reduced engineering hours and minimized use of resources during FAT.

In a different project that lacked a control narrative, both the plant team and integrator experienced leadership turnover. The absence of documentation made it difficult for incoming personnel to understand the project’s status or intent, leading to confusion and delays. With a control narrative in place, knowledge transfer would have been significantly easier.

A tool for team alignment

One of the most overlooked advantages of control narratives is their ability to align cross-functional teams. Operations staff, process engineers and electrical and instrumentation (E&I) technicians each bring different insights and the control narrative helps them communicate effectively by providing a shared reference point.

By bridging these different roles, control narratives translate technical detail into operational clarity. Operations personnel may understand daily processes without being familiar with the programming. Process engineers contribute knowledge of system intent, while E&I technicians help identify unused or misallocated I/O. The narrative brings these viewpoints together into a single, cohesive plan.

Although not the most visible part of an automation project, control narratives play a critical role in ensuring alignment, clarity, and long-term project success. Whether undertaking a large-scale migration or a focused logic change, investing in a strong control narrative can be the difference between guesswork and precision.

Chase Beard, P.E., is controls and automation engineer at Hargrove Controls & Automation, certified members of the Control System Integrators Association (CSIA). For more information about Hargrove Controls & Automation, visit its profile on the Industrial Automation Exchange.