The reference architecture that connects the plant floor to the business — and the model I've used to bring order to fragmented manufacturing systems throughout my career.
ANSI/ISA-95 (internationally, IEC 62264) is the standard for integrating enterprise systems — ERP, planning, business systems — with the control systems that actually run a plant. It gives manufacturers a shared vocabulary and a consistent way to define where one system's job ends and another's begins, which is exactly the kind of question that otherwise gets answered differently by every vendor, every plant, and every consultant. It's built on the older Purdue Reference Architecture and is used, in some form, by the large majority of manufacturers worldwide.
The actual manufacturing process itself — material being cut, welded, assembled, mixed, or moved.
The sensors and actuators that directly monitor and manipulate the physical process — the hardware closest to the work itself.
SCADA and PLC-level control — the systems that monitor and directly control the process in real time.
MES-level systems: production tracking, quality management, scheduling, and the operational data that ties a shift's work together. This is often the least standardized layer in a plant, and the one where the most value gets left on the table.
ERP and business systems — the layer most executives are actually familiar with, and the one that depends entirely on getting the layers below it right.
Early in my career, I introduced the ISA-95 model to an organization that had no standardized way of mapping its manufacturing, quality, and supply chain systems — starting with a footprint of roughly 70 plants and scaling the same framework across a global network of hundreds of sites over the following decade. The value isn't the diagram itself; it's the discipline it forces: every new system, every plant launch, every integration project gets evaluated against the same model instead of reinventing the boundary lines from scratch each time.
For the full technical standard, the International Society of Automation maintains the official reference.
ISA-95 Standard, via ISA.org ↗