What is a virtual PLC system, exactly? It has always sounded enigmatic, but there are now more practical acts. At this year's Hannover Fair in Germany, a start-up company called Software Design Automation displayed a virtualized PLC system solution in Amazon's AWS partner exhibition area. The virtualized PLC system can not only replace the required binding of traditional PLC hardware and software via the digital twin of the CPU, but it can also run the software on the cloud to complete the deployment and management of the PLC group, as well as manage the man-machine interface for PLC group operation.
A near-practical solution
Because hardware-based functions are gradually being replaced by software, the words software-defined technology and software-defined equipment are commonly used in the IT industry. But, can this notion be used to manage industrial machinery and equipment in real-time? Although this appears to be an absurd concept, the answer is yes. The concept is that a proper framework for developing, deploying, and monitoring the operation of virtualized automation assets must be in place.
The SDA-named Munich-based start-up is following in the footsteps of software-defined technology in the IT industry, driving the OT area to produce a software-defined automation (Software Defined Automation, SDA) solution. It virtualizes and manages traditional PLC hardware on top of it. Similar to managing software assets. The PLC operating suite they created for automation engineers virtualizes commercial PLCs using controller digital twins. For example, it can collaborate closely with Bosch Rexroth and Tulip, a Massachusetts-based low-code provider. Alternatively, it can use Siemens' or Beckhoff's open-source PLCs hosted on GitHub to implement industrial control as a service ICaaS.
This virtualization and service-oriented technology route enable industrial automation practitioners to benefit from hardware-independent remote connections, simpler collaborative PLC engineering, and real-time sexuality determination of a virtual PLC. According to SDA data, this virtual real-time controller has so far achieved the actual impact of a deterministic control cycle time of 10ms. At the moment, this may be the most viable option for commercializing virtual PLC. This vPLC solution enables deterministic real-time control on virtual edge servers in conjunction with a full vPLC management interface that is cloud-based.
It helps companies to boost flexibility, productivity, and safety while achieving independence from vendor-specific industrial automation gear when combined with cloud automation engineering solutions. Customers may convert from traditional PLCs to fully virtualized PLC controls operating on the VMware Edge edge computing stack on traditional IT servers near to the plant floor using SDA's solution. Like a traditional PLC, automation engineers can continuously monitor the vPLC via a cloud-based control panel. SDA's cloud-based application enables users to the commission, manage, and monitor vPLC instances from a factory-based server.
SDA Control-as-a-Service Service deconstructs proprietary silos in the control technology stack, allowing a microservices architecture built on top of a real-time control layer to interface natively via APIs like any other contemporary corporate information system, transforming factories into software systems. The current cloud-based PLC management software (SDA TechOps), the PLC code versioning and collaboration software (SDA DevOps), and the software that virtualizes the PLC on the edge server (SDA Virtual PLC) all work together. Install a virtualized PLC system.
Automation experts can now manage PLCs from Siemens, Bosch Rexroth, and Beckhoff as cloud-based software systems, with complete transparency of deployed code, full traceability of code changes, and the capacity to automate code refreshes in minutes, using SDA TechOps. SDA DevOps provides Git-based version management for PLCs, easing the shift to contemporary developer collaboration. Every project update is safely backed up, and changes to specific objects are versioned and clearly presented in a structured text and ladder diagram application via a simple online interface. These approaches enable the automated engineering team to collaborate more effectively, accelerate development, and reduce risk.
When a new feature is required, it may be distributed across the whole PLC system in minutes by pressing a button. Through virtualization, SDA's Virtual PLC decouples real-time control from proprietary hardware. SDA collaborates with VMware, a well-known virtual machine software vendor, to run virtual PLCs on any x86 server, assuring a scan cycle time of 10ms for each virtual PLC. Like traditional PLCs, automation professionals may continually monitor the operation of the vPLC via a cloud-based control panel. Automation engineers may also quickly commission new Codesys controllers and pay a monthly charge for each virtual controller.
This is a significant shift in the industry's game rules, according to SDA founder Josef Waltl, who believes that this method of working makes automation the beginning point for the transformation of industrial processes. All PLCs can be handled remotely, and there is no need to watch PLCs all day long like firemen, whether it is a huge team of engineers driving the complexity of automation further or one automation specialist within the organization. It provides end-to-end solutions to clients as a leading front-line operation, closely connected with equipment providers such as Bosch Rexroth and Tulip. Any Tulip Edge IO, for example, can be converted into a PLC if the front-line operating platform is integrated with the real-time controller via simple API calls without increasing hardware costs.
This advancement would put industrial automation on par with other industries in terms of IT software development. Automation can finally move at a faster pace.
Deep Thoughts on PLC Virtualization
The notion of virtualization is simple: software whose exterior traits and behavior are compatible with specific hardware is really virtualizing specific hardware. No other advancement in the last 60 years of IT development has delivered more quantitative advantages, such as lower costs, higher flexibility, greater scalability, enhanced dependability, and improved performance, than virtualization. Virtualization has had a massive influence on the IT sector. So, why didn't the virtualization movement expand swiftly to OT? In reality, it took the OT sector almost ten years to determine if virtualization could be employed in industrial automation. People gradually learned that there are an increasing number of virtualization applications in the OT environment, and an increasing number of providers completely support the operation of SCADA and DCS platforms in the virtualization environment. Recently, numerous DCS providers have been reported to install virtual controller CPUs when they need to boost the performance feasible with their existing range of controllers or to lower controller prices for important clients. These virtual DCS controllers run on standard IT hardware like Windows or Linux servers.
These virtualized DCS controller devices are not often seen in product catalogs and lack even a model name or stock number. How will the PLC sector, another essential pillar of industrial automation, deal with the virtualization process? To be fully virtualized, a PLC's vendor-specific CPUs, backplanes, racks, IO modules, and accompanying networks must all be virtualized. It necessitates the virtualization of functions executed by PLC CPUs on general-purpose industrial PCs or clusters of PLC controllers executed centralized on general-purpose IT server hardware. The deterministic field bus and/or real-time Ethernet system can be switched while using the optical fiber backplane; similarly, the virtualized IO module can contemplate using an independent I/O terminal block based on ARM.
It also works with commercially available redundant I/O modules/controllers, among other things. These elements combine to produce a virtual PLC software container. So, what are the advantages of this virtual PLC software container for the OT industry? PLCs are an extremely developed form of an industrial controller. The Modicon PLC, which was introduced in 1969, virtually immediately established its structure and shape, although current PLCs have not altered much in these areas. This unique design has endured the test of time. Even the bidding materials presented by General Motors GM in 1968 are out of date in terms of their activities and qualities. Its functional needs are still a critical component of current PLCs. PLC has evolved into an evergreen tree of industrial control after more than 60 years of development.
If we try to increase PLC performance and compensate for some of its shortcomings by virtualizing PLC, the first thing to consider is aiming at plausible application scenarios. For OEM machinery that employs a large number of tiny PLCs, there is no need to virtualize them. Unless this industrial equipment is concentrated in a workshop and has established a PLC cluster, the outcome is plainly not worth the candle.
A PLC's dependability is high enough, its anti-interference ability is strong enough, it can work normally in difficult industrial environments for more than 10 years, and its maintenance cost is extremely low. It is insignificant if the virtualized PLC can be substituted functionally but cannot attain its reliability, electromagnetic compatibility, and environmental adaptability. When it comes to high-volume, high-value items (such as cigarette machines and high-speed filling machinery), the virtualization of PLC will not be worth the candle if the shutdown results in significant losses. Similarly, virtualized PLCs are ineffective when the production cycle is short and high-speed motion control is required.
This is due to the fact that all studies and software products involving virtual PLCs have been carried out since 2012. The deterministic real-time control cycle has never exceeded 10ms. Is this a stumbling block for virtual PLCs? It needs to be seen whether this is the essence of virtual PLC functioning. How can the value of PLC virtualization be realized? PLCs have established a reputation in industrial settings for being cost-effective, dependable, durable, modular, and simple to maintain. So, can virtualization assist PLCs in becoming quicker, less expensive, and more robust? When enterprises count their company's OT assets and IT assets separately, they frequently discover that OT equipment assets not only outnumber IT assets in number but also in value. According to statistics from one of the world's top three energy companies, this multinational company with over 50,000 employees has more than twice the amount of OT equipment assets than global IT assets.
The rationale is obvious. There are several types of OT assets, and standardization and generalization are lacking, whereas IT asset equipment has long been well-standardized and generalized. In this way, once PLC is virtualized, individuals will be able to run PLC systems from multiple manufacturers, such as Siemens, Schneider, and Rockwell, on the same PLC hardware. A PLC cluster can therefore operate as software on a shared IT server or on industrial PCs, similar to running several Windows and Linux operating system environments in VMWare or VirtualBox. Full PLC virtualization will enable operating Schneider Electric's Unity XL programming environment and then switching to a Rockwell Automation Studio 5000 environment or Siemens' STEP 7 environment without the need to change any hardware assets on-site. This potential must be compelling enough to entice additional corporate executives; the key is that it be sufficiently practical and trustworthy.
How Can Virtualization Reduce OT Costs? First, it will develop a "PC-compatible" version of the PLC, allowing many more vendors to participate. Later commercial devices can still be programmed using the engineering tools supplied by major PLC providers. Second, clients will no longer be forced to purchase all of their gear from a single vendor. Field buses and other open standards have helped to alleviate vendor lock-in to some extent throughout the years. Many clients, however, are still at the mercy of the PLC/DCS provider for a major amount of their hardware and software decades after the initial implementation. The binding traces are extremely visible. Finally, it will have an impact on the electrical distributor model. The middleman's position has grown fragile, and it is no longer required to buy PLC/DCS software and equipment from authorized vendors. Because more general-purpose, commoditized technology reduces the necessity for these middlemen, the profits produced by these middlemen are automatically wiped away.
Virtualization is well-known for its versatility and flexibility. A completely virtualized PLC may significantly increase OT flexibility, especially as the market becomes increasingly low-volume and diverse. Intelligent manufacturing relies on the speed and flexibility of production line design, and virtualized PLCs can completely satisfy this requirement. It uses general-purpose IT equipment to enter the production line's control link, allowing low-cost hardware to equip more modern automation systems, promoting innovation in the OT environment, and shortening the coordination and debugging time of PLC clusters necessary when changing varieties.
Simultaneously, when production is switched over, establishing a virtual representation of the operating process and testing the updated process against real-time data to understand the impact of changes on the system is a much-needed capability. PLC virtualization even allows for the easy transfer of automation hardware product providers. For example, if a firm decides to alter production direction, it may transition from a Rockwell system to a Schneider Electric system in preparation for the following product run. At present point, the virtualized PLC may not require or seldom require hardware changes, merely changing and deploying application software. Because virtualization at all levels above L2 in the OT environment has made operations like patch deployment, backup creation, and endpoint protection easier, similar actions have now targeted the L2 level, which is the control layer. Virtualization of facilities.
Most PLC CPUs today have significantly less processing capacity than standard IT CPUs. Even taking a step back and using an industrial PC as the PLC's CPU can result in significant cost savings. Of course, unlike PLC CPUs, industrial PCs are not meant to have a 10- to 15-year lifespan, but this risk is mitigated by clustering and extra tiers of redundancy. In terms of information security, a virtualized PLC may acquire significantly more technical help than a standard PLC. Virtual containers, for example, can enable software firewalls to restrict traffic to and from PLCs; virtual container environments will operate on Linux or Windows environments, which are more secure in terms of network security than traditional real-time operating systems (RTOS) implemented on PLCs.
Of course, several obstacles must be overcome before PLC virtualization becomes a reality. The most critical of these is how to solve PLC determinism and the uncertainty of IT cloud services; how to solve functional problems in the OT industry through virtualization of products that bundle specific software and hardware such as PLCs with consistent external characteristics and behaviors; and some fundamental challenges posed by the performance-centric nature of IT virtualization. Furthermore, the virtualization of PLCs anticipates the participation of numerous vendors, including conventional PLC manufacturers, in this technological revolution. Suppliers that make this potential advantage a reality may become "VMWare in OT," gaining market dominance.
Judgment for the future
The three most generally used fundamental systems in the OT industry, DCS, SCADA, and PLC, have all demonstrated a virtualization trend, which has piqued the interest of several domestic enterprises with high technological sensitivity. For example, Huawei's Zijin Laboratory collaborated with Baoxin and Shanghai Jiaotong University to test a virtual PLC system using deterministic IP communication; China Guangdong Nuclear Power Co., Ltd. collaborated with Shanghai Jiaotong University and Huawei to develop a virtualized DCS for conventional islands of nuclear power plants, employing multiple hot backups of virtualized controllers to replace one-to-one hardware backups. The author has the following fundamental judgments on the worldwide and domestic study of virtualization in the OT field:
The advancement of virtualization in the OT industry is promising and has significant promise, particularly the realization of low-cost software hot redundancy and the flexibility and adaptation of PLC clusters to production process changes, both of which are very appealing. This is not a significant worry for management in the event of a single PLC or DCS system. However, for a large organization, the cost and performance advantages provided by the switch to virtualized PLC/DCS have already piqued the interest and support of certain forward-thinking senior management. This is the enormous potential of virtualization in the realm of OT.
There are still certain obstacles to overcome before PLC virtualization becomes a reality, the most important of which is how to handle the time determinism of PLCs and the uncertainty of IT cloud services. Because PLC frequently needs to cope with high-tempo and high-speed control requirements, it must deal with application programs with scan times on the order of 1ms. In this regard, the virtualization requirements of DCS and SCADA are rather low. With the existing technology, the virtualized PLC can only realize the application program with an order of magnitude of roughly 10ms, therefore the virtualized PLC's application scenarios should be constrained. For example, employing edge servers and edge I/O virtualization technologies to build a data collection system fit for the needs of the Industrial Internet can overcome the problem of insufficient time certainty caused by virtualized PLCs. At the same time, there is no need to try to address the motion control problem with a virtualized PLC.
At the moment, it appears that implementing the deployment and monitoring of virtualized PLC on the cloud server and the operation control of virtualized PLC on the edge server is a more appropriate approach. This option is appropriate for bigger PLC cluster systems.
Overall, classic PLCs have a number of distinct benefits, including long-term reliability in severe industrial settings, good usability, a high degree of modularization, ease of maintenance, and so on. How to inherit and go on in new conditions necessitates tempering and gathering experience, all of which is dependent on engineers and technicians with extensive practical expertise in the OT sector and the ability to handle practical difficulties. In this regard, virtualized PLC must consider the role of current conventional PLC practitioners in order to obtain a strong footing and thrive in industrial control. Only pure software developers are capable of progressing in the technical reform of virtualized PLC.
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