The Virtual PLC (vPLC) concept is gaining traction, and for good reason. It brings software-like flexibility to automation and eliminates the dependency on proprietary hardware. But let’s be honest: legacy PLCs aren’t just going to disappear overnight. They work, they’re reliable, and they’ve been the backbone of industrial automation for decades.
So, how do we introduce a more software-driven approach without the cost and risk of replacing the entire control system?
Virtual PLC: Designed for Gradual Integration
The good news? The Virtual PLC isn’t an all-or-nothing proposition. They can be phased into an existing automation stack with minimal disruption, primarily because they support the same industrial protocols, programming standards, and languages as their hardware-based predecessors. If your legacy PLC communicates over EtherNet/IP, Profinet, or Modbus, a virtual PLC can do the same, allowing it to slot into the system without breaking everything else.
Once it’s in place, the real advantage kicks in: the ability to tap into modern software workflows, remote management, and seamless integration with higher-level systems.
This post provides a clear, step-by-step approach to implementing the vPLC in both brownfield and greenfield facilities, ensuring smooth integration without disrupting operations.
What is a Virtual PLC?
A Virtual PLC represents a fundamental shift in how control systems are deployed. Unlike traditional PLCs, which are tied to dedicated hardware, a vPLC runs as a service on industrial PCs, edge devices, or really any open and off-the-shelf hardware, including PLC hardware with a Linux operating system. This hardware abstraction means greater flexibility in deployment, scaling, and maintenance.
That said, ‘virtual’ doesn’t mean ‘hardware-free.’ The control logic still executes on a computing platform; it’s just no longer locked to a single-purpose PLC box, and when paired with a cloud-native environment for programming, maintenance, and version control, a vPLC creates a foundation for more efficient and scalable automation operations.
Find out how a virtual PLC solves three major automation problems in this guide.
Transitioning with Existing Infrastructure (Brownfield)
The key to integrating a virtual PLC in brownfield facilities is to work with what’s already there rather than against it. The transition can happen step by step, allowing operators to adopt new capabilities at their own pace.
Example use-case case: A Wastewater Pump Station
Let’s consider a simple pump station as you’ll find them all around you if you look closely: A (typically) underground tank, which continuously fills with wastewater, and a redundant pump setup that activates when the level transmitters report a certain fill level.
Let’s add to that some connectivity via modem so that operational data can be sent to a central server, from which SCADA commands can be received, too.
Step-by-Step Transition Guide
Convert or update your PLC Program
Break Free from Vendor Lock-in: Moving away from vendor-specific programming languages and dialects is key to building a more modern and flexible automation system. Converting your PLC program to an open, internationally recognized standard like IEC 61131 ensures greater independence, easier maintenance, and long-term scalability.
Leverage Existing Code: Many traditional PLCs already use IEC 61131-compliant languages, making the transition smoother. If not, conversion tools and not least the rapidly evolving AI landscape are your friends. This is low risk in any case, as you can convert your automation logic without touching your current operations at all, and one of the strong points of vPLCs is their easy deployment to simulation environments to troubleshoot and optimize your code before going into production.
Use a Cloud-Native IDE: a cloud-native integrated development environment (IDE) for virtual PLC programming gives you additional benefits like collaborative engineering and always up-to-date functionality without jumping through the hoops of license management and version matching - it also simplifies centralized code management and bulk updates of your vPLCs, as also described in point 5. further down.
Minimal Physical Intervention – Goodbye, vendor-locked PLC, hello low-cost open-edge device!
Not all traditional PLCs are the same. Some vendors continue to develop their PLCs as a proprietary gatekeeper to lock their customers into their product ecosystem. Others are pushing toward openness and empowering their customers to install the apps and services on the hardware as they see fit.
Replace or Reuse Hardware: Depending on where you find yourself on that scale, if your PLC runs on an open, Linux-based device, you may continue using it. Otherwise, replacing it with a ruggedized, off-the-shelf industrial PC running virtual PLC software delivers the same functionality at a fraction of the cost of traditional PLCs.
This step alone will cut your PLC hardware spending. If we imagine replacing traditional with vPLCs on not just one pump station but many or all pump stations in our example use case, these savings become substantial.
Decouple I/O from the PLC: On the I/O side, you can most likely keep what you have, with a little twist: If you had your I/O cards on the same backplane and directly connected to your legacy PLC, then we’re suggesting you decouple them and turn them essentially into remote I/O.
Example: If a pump station uses EtherNet/IP, connect the I/O to an EtherNet/IP communication module instead of the PLC’s backplane. Then, link this via Ethernet to the virtual PLC host device, same protocol, same control logic, just now it's “remote” and physically decoupled from your PLC unit.
Optimize the Network Setup: To further decouple by scope and purpose, consider adding a switch to manage communication between remote I/O, the virtual PLC host, and your modem instead of using direct Ethernet connections. However, this comes down to preference and balancing hardware costs, cabinet space, and risk distribution. You might also opt for a single device that acts as a switch, modem, and virtual PLC host all in one!
SCADA/HMI Integration
Keep Your Existing SCADA/HMI Setup: What applies to the field-level communication applies equally to SCADA and other higher-level systems in the stack: Your virtual PLC supports the same protocols (OPC UA, MQTT, …) and communication principles as your legacy system and more. In short, you will be able to keep your SCADA and HMI integrations largely intact.
Example: If in our pump station example, every local PLC was supported by a local HMI panel, and SCADA was running on a central server, then you can simply keep it that way.
Third-Party Application Integration
Now, we’re tapping into another benefit of the virtual PLC that may not be obvious at first. However, the software-defined approach of virtual PLC makes them an ideal partner for decentralized publish-subscribe data frameworks that can radiate their value through your entire automation stack.
Choose a Virtual PLC Vendor That Supports a Pub-Sub Data Framework: Look for virtual PLC vendors that offer a Pub-sub data framework out of the box. This means that all operational and system data the virtual PLC generates is published to its nearest data server in a structured, human-readable format. That data server, forming a cluster with other instances in the decentralized framework, can then share data upon request, provided the right permissions are in place.
Having this communication backbone in place makes integrating other data sources much easier, whether it’s SCADA, MES systems, or external services running on the edge or in the cloud.
Bi-Directional Communication & Smart Control: This approach enables bi-directional communication of course, which opens possibilities ranging from monitoring and data collection to machine-to-machine communication to external data sources driving shop floor control.
Enable Remote Operations & Smart Updates
Fleet-Wide Virtual PLC Operations: A virtual PLC, a standardized code base, a Pub-sub data framework, and wireless access create the foundation for centralized updates and fleet-wide vPLC operations at scale.
In our use case, all pump stations are similar, but as is often the case in industrial automation, no two setups are exactly the same. With our virtual control system in place, the same PLC program can now be deployed across multiple pump stations, with minor differences handled through customized tag files or configurations for each station.
In this article, you can find out how the introduction of a virtual PLC overcomes the complexities of multi-vendor PLC fleets.
Centralized Code Management & Bulk Deployment: The master program file is centrally managed in a cloud-based IDE, allowing for version control and bulk rollouts to multiple local vPLCs without disrupting operations.
Smart Control with External Data: You are now also able to build more ‘smartness’ into your control system. As a simple example, you could feed external data from a power price forecasting service directly into your logic and optimize your pumps’ operations for electricity cost. Thanks to the publish-subscribe data framework, this integration is simple and secure, and lets external data trickle down all the way to the local virtual PLC.
Virtual PLC Deployment in a New Infrastructure (Greenfield)
If you’re designing a new automation system from the ground up, you have the luxury of thinking differently. This isn’t just about replacing physical PLCs with virtual ones—it’s an opportunity to rethink control architectures entirely and design your facility in a way that makes it more adaptable to future technological advancements.
Step-by-Step Guide to Greenfield Virtual PLC Setup
Minimal Physical Constraints—Pick Best-Fit Hardware
Industrial PC or Edge Device: Deploy the virtual PLC runtime on a ruggedized industrial PC (ARM or x86) running Linux. You’re no longer forced to buy a specialized PLC chassis.
Remote I/O Modules: Instead of a single backplane, choose modular, networked I/O (EtherNet/IP, PROFINET, etc.) placed where sensors and actuators physically reside. This reduces wiring complexity and makes expansions easier.
Network Layout: Design from the ground up with industrial Ethernet switches, VLAN segmentation, and redundant links if needed, without having to work around outdated hardware.
SCADA/HMI Integration—All Open from the Start
Native Protocols (MQTT, OPC UA, NATS): Unlike a brownfield scenario, you can standardize on open, publish-subscribe protocols from day one, avoiding “spaghetti” point-to-point connections, which we have explained in this article in more depth.
Local & Remote Dashboards: Place HMIs on the line (touchscreen panels running Linux or Windows) and set up remote SCADA stations. All data flows through your central integration HUB, ensuring consistent, real-time visibility.
Third-Party Application Integration—No Retrofits Needed
Publish-Subscribe Data Framework: The virtual PLC automatically pushes its data to a centralized server (OTee HUB) that can feed MES, analytics, or machine-to-machine coordination. In a greenfield build, this is simple to embed right away.
AI, ML, & Other Services: If you’re aiming for advanced predictive maintenance or adaptive control, you can hook those applications in from the get-go—no bridging or special adapters are required.
Enable Remote Operations & Smart Updates from Day One
Zero-Trust Security & Encrypted Access: Build modern security principles at the blueprint stage. You can use role-based access control (RBAC) and certificate-based authentication from the start, avoiding retroactive “patch” solutions.
OTA Updates & Fleet Management: Even if you have just one packaging line now, a fully software-defined approach lets you rapidly scale to multiple lines in the future—pushing updates and new code versions via the HUB.
Centralized Code & Version Control: Because you’re in a greenfield setting, you won’t juggle older PLC code bases. One modern code repository can handle all lines or machine variants, with site-specific parameters stored in separate config files.
Key Considerations for a Virtual PLC-Based Infrastructure
Think in terms of technology, not products
Don’t just swap one vendor’s PLC for a virtualized equivalent. Rather, design your system around technologies that best support your use case: which field level protocols, which data architecture and integration capabilities, and which cybersecurity principles fulfill your operational requirements? Without being limited to a particular vendor’s product palette, you can now pick best-in-class technology providers to achieve your technology-centered vision.
The PLC is now a commodity
With software-defined control, the virtual PLC can be deployed dynamically where needed. This means you can rethink control distribution based on scope, location, and redundancy. Traditionally, when investing in a costly PLC, you’d try to pack in as much functionality as possible.
Take a pump station: Chances are, the PLC isn’t just controlling the pumps but also handling heating/cooling, access control, and maybe burglar alarms. It works, but it also blurs responsibilities and makes the logic harder to maintain.
A virtual PLC removes these constraints. They don’t translate to cost the same way traditional PLCs do. You can deploy multiple vPLCs on a single host or distribute them across underutilized compute resources, making control more structured and easier to manage.
Redundancy Without Extra Hardware
Designing for redundancy in control doesn’t necessarily mean duplicating PLCs anymore. Back-up vPLCs could be deployed on host devices whose primary function is something else (panel screens operating on a Linux OS, switches, and other edge devices).
Final Thoughts on Implementing the Virtual PLC
Switching to a virtual PLC isn’t about ripping out what already works, but it’s about taking a measured, step-by-step approach that makes your automation system more flexible, cost-effective, and easier to manage.
Whether you’re working with existing infrastructure (brownfield) or designing from scratch (greenfield), the goal is to introduce improvements without disrupting operations or adding unnecessary risk.
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