A critical moment in the development of industrial automation: How will virtual PLCs change automation?

Since the advent of Industry 4.0 more than a decade ago, information technology (IT) has been influencing industrial automation systems. This initiative has made risk-averse industrial participants recognize the value and benefits of using "IT-ized" architectures, such as continuous optimization through access to raw process data. It has also created a data-driven future vision, modeling and testing products and production processes through digital twins.

　　The "IT-ization" of automation architecture began with Ethernet-based industrial networks and gave rise to the creation of the industrial edge, a space where traditional automation meets the IT world on the factory floor. As this trend continues, we are now witnessing the migration of real-time control from dedicated hardware to hosted IT environments.

　　 Starting from the data center

　　Data centers are one of the fields where virtualization technology is applied. Before virtualization, data centers consisted of dedicated functional servers running single applications (databases, email, file sharing, customer relationship management, enterprise resource planning). Each server had to be managed, configured, and scaled individually to meet the needs of its application or service. Virtualization greatly reduced the number of physical servers required, lowered energy consumption, and provided better visibility and manageability for IT operations. Server virtualization was a step toward today's software-defined data centers and cloud computing infrastructure.

　　Industrial automation technology seems to be moving along a similar path. Shanghai Automation Instrumentation Third Factory For automation solutions, this shift means integrating multiple automation functions such as visualization, production management, or batch control into virtual machines running on general-purpose hardware and software platforms (factory servers). While electromechanical devices like sensors, actuators, and motors remain on the machines, 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 daily functions of the automation system should remain unchanged, but maintenance personnel may need to learn new skills to handle operational issues.

　　 How will virtual PLCs change automation?

The emergence of virtual PLCs (vPLCs) has sparked much thought. Can virtual PLCs directly replace traditional PLCs? How do they compare in 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 bundled with industrial PCs. Edge platforms typically support applications and devices from an ever-expanding ecosystem of products and solutions (including third parties). For example, dedicated platforms like Siemens Industrial Edge provide tools for deploying and monitoring automation assets and service performance, enabling applications and devices to communicate easily with each other while occupying minimal space.

　　 Deployment for end users

　　Traditional PLCs are usually deployed manually, and parameters often need to be set manually as well. Virtual PLCs, however, are deployed like IT assets through "orchestration"—the process of automatically configuring, provisioning, and managing assets using general IT tools. After acquiring certain IT skills, automation engineers can deploy and monitor a full set of controllers in 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 cost savings from centralized management of automation assets is enormous.
 

　　 Deployment for machine manufacturers

　Although most machine manufacturers prefer to deliver machines with identical configurations and PLC programs, in reality, even standard machines often require modifications to meet customer needs and requirements. Virtual PLCs offer significant advantages to machine manufacturers: traditional PLC hardware comes in different sizes and capacity specifications, whereas virtual PLCs have only one "model" that can be scaled up or down anytime according to each machine's needs.
 

　　 Reducing capital costs

　　Virtual PLCs run on servers, and if multiple virtual PLCs are installed on a single hosted device, users can reduce capital costs. So, how many virtual PLCs can be installed on one server, and what are the limitations? Generally, it is feasible to install clusters of 10 to 20 virtual PLCs per server, but this depends on the specific tasks of the virtual PLCs. Deterministic performance in hard motion control is a key test for PLCs. Some virtual PLCs can perform standard motion control tasks like their hardware-based counterparts, but for motion control (coordinating multiple servo axes), technical experts recommend using traditional PLCs and dedicated technology modules for greater reliability.

　　 Picking (primary packaging)

　　High-speed pick-and-place robots can handle products that need to be boxed. These robots can load blister packaging units or other packaging materials, manage the feeding flight of pillow packaging machines, and form matrices on the discharge conveyor. By using proprietary sorting software integrated with vision systems, these robots can identify the position, orientation, and type of parts and assign tasks to the corresponding robots for processing.

　　 Scalability and flexibility

　　Virtual PLCs make automation systems more flexible and scalable. The system size can be easily expanded or reduced by changing the number of virtual PLC instances in use without installing or removing hardware. Users only pay for the controllers currently in use—a very attractive model for machine manufacturers who regularly produce and ship machines. Due to their size and available space, traditional PLCs pose some challenges for factories wanting to scale quickly. Virtualization allows new control strategies to be developed and tested before implementation on physical PLCs, enabling flexible expansion of factory automation lines. This greatly reduces costs and risks of errors during expansion.

　　 Device and application management

　　Virtualized systems are "orchestrated," meaning applications and devices can be quickly deployed, allocated, and configured through automated tasks. This allows the entire software-defined automation system, smart devices, and applications to be deployed, monitored, and managed using general-purpose tools.

　　 Support for the system

　　Machine manufacturers often invest heavily in PLC code development, so it is not surprising that virtual PLCs usually support code and data structures, enabling users to leverage their existing intellectual property and familiar engineering tools. For example, Siemens' virtual controller Simatic S7-1500V is configured the same way as traditional PLCs using its TIA Portal software, so users can continue to use existing code developed for multiple generations of Siemens PLCs. This also applies in reverse: if needed, users can easily switch back to traditional PLCs to reduce any change risks and support gradual migration.

　　 Higher efficiency

　　Virtual PLCs are deployed at the industrial edge, which is the domain where old and new automation systems integrate within the IT environment. For example, the Simatic S7-1500V runs on Siemens' industrial edge platform, where applications and devices can be centrally monitored in this universal environment that promotes openness and data sharing, bringing a range of benefits. Users can operate and maintain manufacturing equipment based on insights gained from data-driven approaches, helping to optimize processes and even predict unexpected 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

　　Are automation systems using virtual PLCs lower in procurement costs compared to traditional automation systems? How do their lifecycle costs compare to traditional PLC systems? There is no definitive conclusion yet regarding the cost comparison between virtual PLCs and traditional PLCs. Although virtual PLCs still require hardware to operate, users can deploy multiple virtual PLCs on a single server, which reduces the overall number of devices and saves control cabinet space. However, virtual PLCs only replace the central processing unit (CPU) of the automation system. Input/output (I/O) modules, sensors, actuators, and operator panels are still required, and these may account for a large portion of the total control system cost.

　　Engineering costs can be reduced by adopting a DevOps approach for lean software development, which shortens development time while ensuring code quality and consistency, and can also achieve additional cost savings.

　　The introduction of virtual PLCs marks a pivotal moment in the development of industrial automation. By combining the robustness of traditional PLC functions with the agility of virtualization technology, virtual PLCs offer flexibility, scalability, and integration capabilities. As industries continue to embrace digital transformation, adopting virtual PLCs is expected to improve efficiency, reduce costs, and bring new opportunities for innovation in the manufacturing sector.

　　The significance of virtual PLCs is not to replace traditional PLCs, Shanghai Automation Instrumentation Co., Ltd.   but to deploy and manage PLC functions in a data-centric environment and fully leverage all the advantages brought by modern IT tools and developments. Understanding the nuances of virtualization and its impact on automation architecture will be crucial. Embracing these advancements not only enables future-oriented industrial operations but also paves the way for a more connected and intelligent industrial environment.