I/O termination that virtualises the signal-processing and protocol-conversion layer in software running on standard servers, rather than in dedicated I/O card firmware.
Software-defined / virtualised DCS & PLC
Control Systems — DCS · PLC · ESD · HMI
Over-Promise
Near-term · 2–5 yrs
Evidence E3 · First production use
Control software that runs on standard servers or industrial PCs instead of proprietary controller hardware. The first open-architecture plant and server-based controllers from mainstream suppliers are now in production; the long-term support model is still unproven.
Separating control software from hardware
A conventional DCS controller or PLC is a closed product: processor, real-time operating system and control runtime are designed, certified and supported together. When the hardware becomes obsolete the owner usually replaces the controller and often migrates the application, even though the control strategy has not changed. Over a plant's 20- to 30-year life this can happen several times.
Software-defined control keeps the runtime but moves it onto general-purpose computing, as a virtual machine or a container on a real-time-capable host. Redundancy becomes a function of the hosting layer, controllers can be created from templates and backed up as images, and I/O is reached over the network. There are two distinct routes. In vendor-integrated platforms one supplier provides the runtime, the hosting stack and support. In open architectures, such as the Open Process Automation Standard (O-PAS), components from different suppliers are combined by the owner or a system integrator.
| Vendor-integrated | Open architecture (O-PAS) | |
|---|---|---|
| Who integrates | The control-system supplier | The owner or a system integrator |
| Examples in production | Siemens S7-1500V at Audi; Emerson DeltaV IQ | ExxonMobil Baton Rouge Lighthouse |
| Main benefit | Hardware independence with one point of support | Hardware independence and component-level competition |
| Main open question | Lock-in moves to the software layer | Who carries lifecycle responsibility |
What is actually running
ExxonMobil's Open Process Automation "Lighthouse" project at its resins finishing plant in Baton Rouge, Louisiana, is the most cited open-architecture example. It is built on O-PAS version 2.1, with distributed control nodes running IEC 61499 runtimes, about 1,000 I/O points, and a system integrator rather than a DCS supplier responsible for support. It passed factory acceptance testing in August 2024, was cut over during a scheduled outage in November 2024, and produced its first saleable product on 18 November 2024 12. Reports from early 2025 describe stable operation since start-up, about a week of operator training because the HMI graphics were kept unchanged, and a next project of around 200 I/O 1. Published accounts differ on whether the system has around 100 controllers or around 100 control loops 12; we have used the I/O count, on which they agree.
On the vendor-integrated side, Siemens describes its SIMATIC S7-1500V as the first TÜV-certified virtual fail-safe controller. It runs on Audi's Edge Cloud 4 Production infrastructure on the e-tron GT line at Böllinger Höfe, after roughly three years of requirements definition and testing 3. Emerson's DeltaV IQ controller packages real-time control and redundancy in virtual machines on hyperconverged servers. Emerson introduced it with DeltaV version 15 Feature Pack 3 in March 2025 4 and, at its user conference in May 2025, said that a pair of servers can run up to 36,000 I/O, against about 1,500 for a hardware controller 5.
The hard questions are about the life cycle
The technical questions are reasonably well bounded: real-time performance on the chosen hardware, deterministic network paths to I/O, and failover behaviour when a host fails. Suppliers and early adopters have answered them for the configurations they have tested.
The harder questions are about the life cycle. A hardware controller is supported as one unit for decades. A software-defined controller depends on a hypervisor, an operating system, server firmware and network switches, each with its own patch and end-of-life schedule, typically far shorter than the plant's. Somebody has to own compatibility testing of every combination. In an IT data centre that is routine; in an OT environment that must run for years between turnarounds it is a new discipline. Cybersecurity changes shape for the same reason: the hosting layer becomes part of the control system and must sit inside the same zone design, patching regime and monitoring.
There is also a skills shift. Commissioning a controller now includes server, virtualisation and network configuration, and a fault may sit in any layer. Owners considering the move should be honest about whether their own OT team, the supplier or an integrator will hold that knowledge for the next twenty years.
Where to start
The sensible early applications are those where flexibility has obvious value and the consequences of a mistake are contained: simulation and operator training systems, migration of obsolete controllers where the application can be preserved, modular and batch plants, and new units with non-critical control. Safety systems are a separate question. Certified virtual fail-safe control has appeared in discrete manufacturing; process-industry safety instrumented systems are likely to stay on dedicated hardware for some time.
Evidence timeline
- Aug 2024ExxonMobil OPA Lighthouse passes factory acceptance testing. 1
- Nov 2024Lighthouse cut over and producing saleable product from 18 November. 2
- Mar 2025Emerson releases DeltaV v15 Feature Pack 3, including the server-based IQ controller. 4
- May 2025Emerson states DeltaV IQ can run up to 36,000 I/O on a pair of servers. 5
- 2025Siemens describes the TÜV-certified S7-1500V virtual controller in use at Audi Böllinger Höfe. 3
Why it sits at the Over-Promise stage
Real systems are now in production, and supplier marketing has run well ahead of them. We keep the entry at the Over-Promise stage because the number of production plants is still very small, no software-defined system has yet been through a full hardware refresh in a process plant, and expectations of cost savings are ahead of the evidence. The 52 percent hardware and software saving often quoted for the ExxonMobil approach comes from an earlier analysis rather than measured project results 1, and should be read that way.
We expect the near-term horizon to hold for new projects and controller migrations. Replacement of the installed base will take much longer.
Adoption signals to watch
- A second and third O-PAS production system from operators other than ExxonMobil.
- A software-defined control system completing a hosting-hardware refresh without changes to the control application.
- Published lifecycle-support commitments for hosting stacks that match plant life.
- Certified virtual safety controllers used in process-industry applications.
Questions to ask before committing
- Who is responsible for testing compatibility between the control runtime, hypervisor, operating system and server firmware after each update?
- What cycle time and jitter are guaranteed on the proposed hardware, and how was that demonstrated?
- What happens to control when a host fails, and how long does failover take?
- Is the hosting layer inside the control-system security zone, with OT-appropriate patching and access control?
- Who will hold the virtualisation and networking skills on site in ten years?
Terms used on this page
- Virtual PLC
- A controller runtime delivered as software to run on standard computing hardware.
- IEC 61131-3
- The standard that defines the common PLC programming languages.
- IEC 61499
- A standard for event-driven, distributed function-block applications, used by some software-defined platforms.
Sources
- New insights: 100-controller ExxonMobil Open Process Automation
- Plug-and-play punches in
- Factory automation: virtual PLC at Audi
- Emerson enhances control system software to increase operational agility
- Innovations sparkle at Emerson Exchange 2025
Related technologies
See this entry on the full maturity map · All Control Systems entries · How placements are made. Stage and time-horizon placements are editorial judgements based on the public sources listed above, as of October 2026. They are not engineering, safety or investment advice; see the Terms of Use.