Imagine a machine builder preparing the next release of a packaging machine. One customer needs a different set of operator views; another wants additional diagnostics; a third requests an interface to an existing line. The core machine remains recognizable, but its software requirements are diverging.
The question is no longer simply how to program each machine. It is how to develop those variations without maintaining a separate, increasingly fragile project for every configuration, and how to keep the installed machines supportable after delivery.
Our earlier article on why industrial automation is becoming software-defined described the broader direction. For machine builders, its practical meaning emerges in a more ordinary sequence of work: designing a machine family, commissioning individual machines, releasing changes and supporting them years later. Software-defined automation changes how those steps are organized. It does not remove the engineering obligations attached to a physical process.
Many OEMs already reuse control code, visualization objects and communication drivers. The larger change is to treat that reuse as an architectural decision rather than as a collection of files copied from one project to the next.
A machine family might share core sequences, diagnostics and data definitions while differing in I/O, options, interfaces or customer-specific behavior. If those differences are buried throughout the application, every new variant can become a new branch that must be tested and maintained. If common functions and machine-specific configuration have clear boundaries, engineers can see which changes belong to the platform and which belong to an individual machine.
This does not require a single universal program; instead it requires a deliberate relationship among reusable modules, configuration, interfaces and the hardware on which they run. A new option can then be considered as a change to a defined part of the architecture, with its dependencies and tests understood before it reaches a customer site.
The benefit is potentially significant for an OEM building several related machines: engineering effort can be focused on differences that matter to the application. The condition is equally important. Shared software creates shared responsibility. A change to a common module may affect many configurations, so the OEM needs to know exactly where that module is used.
“Hardware independence” is often used as shorthand for software-defined automation. It deserves a more precise reading. There is a difference between reusing a software design on several machines in one environment and running the same application, unchanged, on any controller.
PLCopen’s FAQ on IEC 61131-3 portability makes this distinction unusually clear. Even when controllers support the same programming standard, I/O addressing, supported features, task scan rates and implementation-specific limits can prevent a project from being copied directly from one vendor’s PLC to another. A common language is useful; it does not by itself guarantee a common runtime.
The practical consequence is that an OEM has to define the scope of portability before promising it. A common application structure can make code easier to reuse across a machine family. Moving that code to another runtime or controller still requires checking its hardware interfaces, execution behavior and supported features. These are different claims, with different levels of testing behind them.
For a machine builder, the useful question is therefore specific: which part of the software should remain reusable if the hardware changes? It may be a diagnostic module, a visualization concept, a data model or a control function. Each has different dependencies. Listing them early is more useful than assuming portability will appear later because a component has been called “software-defined.”
When applications can be configured and deployed more independently, commissioning starts to look different. An OEM may create a tested baseline for a machine family and then apply the approved options for each order. The engineering team needs to know which version was installed, which configuration it used and which hardware and runtime it was validated against.
That record matters after delivery. A service engineer investigating a fault needs to distinguish a software defect from a site-specific configuration change or a hardware dependency. The OEM also needs a controlled way to move a tested improvement to other eligible machines without assuming every machine in the field is identical.
This is where software-defined automation becomes a lifecycle discipline. The release is a version that may need to be identified, tested, installed, supported and eventually replaced. For the OEM, this means planning how changes are validated and how service teams can tell which machines are eligible for a given update.
In fact, NIST’s Guide to Operational Technology Security, section 6.2.11, pp. 124–125 emphasizes testing patches for operational effects, documenting how and when they are applied and planning deployment around OT outages. Those principles are especially relevant when software changes could affect control applications or machine availability. Easier distribution should be matched by clearer approval, testing and recovery procedures.
A machine may have computing resources capable of running several applications. That creates opportunities to place visualization, communication, data processing and, in some architectures, control on a shared platform. It also creates a question that cannot be answered by software packaging alone: what happens when these workloads compete for resources or when one of them fails?
The documentation for Intel Edge Controls for Industrial is instructive here. It describes virtualization and containerization for workloads with different criticality levels, but also details the real-time kernels, CPU isolation and other measures used to address deterministic behavior. The need for those measures shows why running a control application as software is only the beginning of the design work.
An OEM must still assess timing, fault behavior, availability, safety requirements and the expected effect of updates on neighboring applications. Some functions may be suitable for a shared compute environment; others may remain on dedicated controllers. Software-defined automation gives engineers more placement options. It does not make those constraints disappear.
Even a well-structured application needs to exchange information with the rest of the machine. Stable interfaces can let an OEM change a diagnostic or visualization function without rebuilding every integration around it. The OPC UA overview and concepts specification shows one way to define the structure and exchange of industrial information across applications and devices. That is an interoperability mechanism; moving executable control code to another runtime remains a separate engineering task.
For maintenance, the distinction is useful. A diagnostic application may be updated independently if it reads a documented machine interface and the OEM controls changes to that interface. The benefit depends on version compatibility and testing, not simply on choosing a common communication protocol.
The most practical change for the machine builder is a shift in what the OEM designs. Alongside the machine’s mechanical and electrical architecture, it must define the boundaries of its software: what can be reused across variants, what belongs to a particular installation, how versions are tracked and which functions can change without disturbing others.
This may lead to more modular applications, shared engineering assets and a more controlled release process. It can also expose dependencies that were previously hidden inside a project file. The result is not automatic hardware independence, faster updates in every case or a reason to consolidate every function. It is the opportunity to make software evolution an intentional part of machine design.
For a machine builder, the decisive question is simple: when this machine needs to change, which parts can evolve, and what must be revalidated before it runs again? A credible software-defined architecture should make that answer easier to give throughout the machine’s life.