Critical Moment in Industrial Automation Development: How Will Virtual PLCs Transform Automation?
[Instrument Network - Industry Science Popularization] Since the advent of Industry 4.0 over a decade ago, information technology (IT) has been influencing industrial automation systems. This initiative has helped risk-averse industrial stakeholders recognize the value and benefits of adopting "IT-enabled" architectures—for instance, achieving continuous optimization by accessing raw process data. It has also fostered a vision of a data-driven future, where digital twins are used to model and test products and production processes.
The "IT-enablement" of automation architectures began with Ethernet-based industrial networks and gave rise to the creation of the industrial edge—a space in factory workshops where traditional automation intersects with the IT world. As this trend continues to evolve, we are now witnessing the migration of real-time control from dedicated hardware to hosted IT environments.
Starting from Data Centers
Data centers were among the earliest domains to adopt virtualization technology. Before virtualization, data centers consisted of dedicated function-specific servers running single applications (databases, email, file sharing, customer relationship management, enterprise resource planning). Each server had to be managed, configured, and scaled independently to meet the maximum demands of its respective application or service. Virtualization significantly reduced the number of physical servers required, lowered energy consumption, and provided better visibility and manageability for IT operations. Server virtualization marked the first step toward today’s software-defined data centers and cloud computing infrastructures.
Industrial automation technology seems to be following a similar path. For automation solutions, this shift means integrating multiple automation functions—such as visualization, production management, or batch control—within virtual machines running on general-purpose hardware and software platforms (factory servers). While electromechanical devices like sensors, actuators, and motors remain on the machines themselves, the traditional functions of programmable logic controllers (PLCs) installed in electrical control cabinets can now be virtualized in containers and deployed on factory servers, alongside other software. For machine operators, the day-to-day functions of the automation system should remain unchanged, but maintenance personnel may need to acquire new skills to address operational issues.
How Will Virtual PLCs Transform Automation?
The emergence of virtual PLCs (vPLCs) has sparked numerous questions: Can virtual PLCs directly replace traditional PLCs? How do they compare in terms of performance? Which applications will remain the domain of traditional PLCs? What new opportunities do virtual PLCs create? Below are some potential advantages and considerations of virtual PLCs in industrial applications.
Virtual Deployment
Unlike some soft PLCs, virtual PLCs can be purchased and downloaded like applications, then installed and integrated in industrial edge environments—without being tied to industrial PCs (IPCs). Edge platforms typically support applications and devices from an expanding ecosystem of products and solutions, including third-party offerings. For example, dedicated platforms like Siemens Industrial Edge provide tools for deploying and monitoring automation assets and service performance. These tools enable seamless communication between applications and devices while occupying minimal space.
Deployment for End Users
Traditional PLCs are usually deployed manually, with parameters often requiring manual configuration. In contrast, virtual PLCs are deployed through "orchestration"—an automated process using common IT tools to configure, provision, and manage assets—just like IT assets. With basic IT skills, automation engineers can deploy and monitor a full set of controllers across machines, production lines, and entire factories configured with a mix of software-defined and physical devices. Today, a large manufacturing plant may contain hundreds or thousands of PLCs, so the potential for cost savings through centralized management of automation assets is substantial.
Deployment for Machine Manufacturers
While most machine manufacturers prefer to deliver machines with identical configurations and PLC programs, standard machines often require modifications to meet customer needs and requirements. Virtual PLCs offer significant advantages to machine manufacturers: Unlike traditional PLC hardware, which comes in various sizes and capacity specifications, a virtual PLC has only one "model" that can be scaled up or down on demand to match the needs of each machine.
Reduced Capital Costs
Virtual PLCs run on servers, and users can lower capital costs by installing multiple virtual PLCs on a single hosted device. But how many virtual PLCs can be installed on one server, and what are the limitations? Generally, a computing cluster with 10 to 20 virtual PLCs per server is feasible, though this depends on the specific workload of the virtual PLCs. Hard real-time motion control is a key test for PLCs. Some virtual PLCs can perform standard motion control tasks as effectively as their hardware-based counterparts, but for advanced motion control (coordinating multiple servo axes), technical experts recommend traditional PLCs with dedicated technology modules for greater reliability.
Picking (Primary Packaging)
High-speed pick-and-place robots efficiently handle products that need to be packed into boxes. These robots can load blister packaging units or other packaging materials, manage the infeed flight of horizontal form-fill-seal (HFFS) machines, and form matrices on discharge conveyors. Using proprietary sorting software integrated with vision systems, these robots can identify the position, orientation, and type of components, then assign tasks to the appropriate robots for precise handling.
Scalability and Flexibility
Virtual PLCs make automation systems more flexible and scalable. The size of the system can be expanded or reduced simply by adjusting the number of virtual PLC instances in use—no need to install or remove hardware. Users only pay for the controllers they currently use, which is an attractive model for machine manufacturers that regularly build and ship machines. Due to size and space constraints, traditional PLCs pose challenges for factories looking to scale quickly. Virtualization allows new control strategies to be developed and tested before being implemented on physical PLCs, enabling flexible scaling of a factory’s automation lines. This significantly reduces costs and the risk of errors during the scaling process.
Device and Application Management
Virtualized systems are "orchestrated," meaning applications and devices can be rapidly deployed, provisioned, and configured through automated tasks. This allows the entire software-defined automation system, smart devices, and applications to be efficiently deployed, monitored, and managed using common tools.
Support for Legacy Systems
Machine manufacturers often invest heavily in developing PLC code, so it is unsurprising that virtual PLCs typically support legacy code and data structures. This enables users to leverage their existing intellectual property (IP) and familiar engineering tools. For example, Siemens’ virtual controller, the Simatic S7-1500V, is configured in the same way as traditional PLCs using its TIA Portal software. This allows users to continue utilizing existing code developed for multiple generations of Siemens PLCs. The reverse is also true: if needed, users can easily switch back to traditional PLCs to mitigate the risk of changes and support phased implementation.
Higher Efficiency
Virtual PLCs are deployed at the industrial edge—the area where legacy and new automation systems integrate within an IT environment. For example, the Simatic S7-1500V runs on the Siemens Industrial Edge platform, where applications and devices can be centrally monitored in a common environment. This environment promotes openness and data sharing, delivering a range of benefits. Users can leverage data-driven insights to operate and maintain manufacturing equipment, helping optimize processes and even predict unplanned downtime and failures before they occur. These capabilities can be further enhanced by other applications running on the same edge platform, such as Profinet monitoring.
Procurement and Lifecycle Costs
Is the procurement cost of an automation system using virtual PLCs lower than that of a traditional automation system? How does its lifecycle cost compare to a traditional PLC system? There is no definitive conclusion yet regarding cost comparisons between virtual and traditional PLCs. While virtual PLCs still require hardware to run, users can deploy multiple virtual PLCs on a single server, reducing the total number of devices and saving cabinet space. However, virtual PLCs only replace the central processing unit (CPU) of the automation system. Input/output (I/O) modules, sensors, actuators, and human-machine interfaces (HMIs) are still necessary—and these can account for a significant portion of the total cost of a control system.
Additional cost savings can be achieved by adopting a DevOps approach for lean software development, which shortens development time while ensuring code quality and consistency.
The introduction of virtual PLCs represents a critical moment in the development of industrial automation. By combining the robustness of traditional PLC functions with the agility of virtualization technology, virtual PLCs offer unprecedented flexibility, scalability, and integration capabilities. As industries across the board continue to embrace digital transformation, the adoption of virtual PLCs is expected to improve efficiency, reduce costs, and unlock new opportunities for innovation in the manufacturing sector.
The significance of virtual PLCs lies not in replacing traditional PLCs, but in deploying and managing PLC functions in a data-centric environment while leveraging all the advantages brought by modern IT tools and advancements. Understanding the nuances of virtualization and its impact on automation architectures will be crucial. Embracing these advancements will not only enable future-proof industrial operations but also pave the way for a more connected and intelligent industrial landscape.