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May 26, 2023


When VMware developed an efficient virtual machine (VM) for computer operating

When VMware developed an efficient virtual machine (VM) for computer operating systems, it transformed IT and eventually paved the way for cloud and modern IT services. Now Siemens is paving the road for a VM for the brains of industrial equipment called a Programmable Logic Controller (PLC).

It's not the first virtual PLC (vPLC), but it's coming from Siemens, which provides the brains for about a third of the PLCs currently in factories, power plants, water treatment facilities and other industries. They just introduced the first one working in production equipment and showed how it could be integrated into the Siemens industrial cloud ecosystem it calls the Xcelerator portfolio.

This will pave the way for bringing operational technology (OT) into the cloud and connecting it to IT systems. Further, it will help bring the kinds of agile software development processes pioneered in the cloud to industrial equipment.

Mind you, people will not be running plant equipment from the cloud directly. Safety critical and expensive equipment can't tolerate the kind of delays we are willing to suffer accessing Slack or Zoom. Rather Siemens is developing a strategy of running vPLCs on a private cloud running within factories and facilities located adjacent to or directly connected to industrial equipment via low latency and resilient networks.

A second benefit of this approach is that it extends the utility and testability of digital twins for equipment. In addition to being able to design the physical devices, testers will be able to run different configurations of vPLCs on the device to identify and remediate problems earlier in the development cycle. They could also explore the impact of different control algorithms virtually to improve product quality or output and extend the underlying equipment's life.

CODESYS has offered hardware-independent VLCs for over 20 years, promising cost savings in hardware acquisition, increased flexibility, and improved security updates. The company promises to let enterprises transform any modern system into an industrial control with support for Windows, Linux, and ARM computers.

Last year, Software Defined Automation announced a partnership with VMware to run virtual PLCs on any x86 server with a cycle time of less than 10 milliseconds. SDA developed a DevOps workflow for operational technology that supported the cloud-based management of existing PLCs, a Git-based versioning and collaboration tool, and an edge server for running PLCs.

Because of the tighter integration with its own industrial ecosystem, Siemens has been able to get the cycle time down to 1 millisecond, further extending the use cases. The new vPLCs run on virtual edge devices, which can run on virtual machines like EXSI server and vSphere. In the future, they will also be able to run on Kubernetes.

Bernd Raithel, Director of Product Management & Marketing in the Factory Automation business unit of Siemens Digital Industries, says:

There were SoftPLCs before, i.e., PLCs running on an IPC, but up to now, it hasn't been possible to run PLCs in a virtual environment due to missing real-time features to guarantee a sufficient response time. Over the last years, the real-time features in CPUs and virtualization environments improved to the extent that running a PLC in virtualized environments with response times of 1ms is now possible. With increased workloads in manufacturing processes for quality control, track & trace, and predictive maintenance, the PLC Control is just one of many applications running during manufacturing. Running all these processes in virtualized environments allows for centrally managing and deploying these applications, increasing the flexibility to change manufacturing as needed.

The new virtual technology will complement rather than replace existing hardware PLCs, just like the VMs have not replaced the need for bare metal servers for the most performant applications. Hardware controllers are extremely robust, reliable and have been used for many years. The new vPLCs will initially provide the most value for companies looking into more flexible production. They will make scaling and fine-tuning automation applications easier without relying on specific hardware.

They will also make it easy to roll control over to a backup if a problem happens with the primary controller. While the most safety-critical industrial equipment today might need a parallel backup, it will allow teams to provide resilience with the same kind of approach used in RAID today, where one system could provide fault tolerance to multiple primary systems instead of just one.

It could also expand the role of app stores in powering industrial equipment down the road. For example, experts in different kinds of manufacturing processes could code their domain expertise into vetted golden images, as is done with IT today. Enterprises could download these for a specific process, version them, and then deploy them across one or more machines. If problems are discovered, they could roll back to the last working version. Raithel says:

Virtualized applications (vPLC and others) allow companies to react faster to changing market conditions and production requirements. Like on a smart phone, operators can add and delete applications depending on the current need of their production. Having everything virtualized also brings the real and digital worlds closer together. Companies can run their PLC (vPLC) and digital twins on the same platform and use digital twins during production as xDT (executable digital twins) and provide additional input to the PLC to control the production process.

Another big bonus is that it will improve the ability to collect data from equipment to enhance predictive maintenance and operational performance. Raithel explains:

These new offerings allow customers to collect more data from their automation equipment (i.e., new SINAMICS drives) and enhance it better with ERP and other IT data on a vPLC / Virtual Edge device to create more sophisticated algorithms for predictive maintenance, which will help customers to reduce downtime and direct maintenance precisely to the machine need. More data will also lead to more insights into the production processes, which can be fed back into digital twins of the machine and production process, which will help improve factory operations. Virtual workloads are centrally managed, which increases the speed to react to changing production requirements and reduces the need for PLC technicians at every site, which will be helpful due to changes in the workforce demographics.

Innovation in the deployment and management of virtual machines has underpinned all the major innovations in IT over the last couple of decades. This new work in virtualizing PLCs could similarly impact industrial equipment.

One area where this could become critical is security. Industrial control systems have traditionally been protected by obscurity since hackers familiar with IT equipment may not be familiar with the intricacies of OT systems. The impact of Stuxnet on destroying the Iranian reactors in 2010 was a wake-up call for the devastating impact of a cyber attack on physical infrastructure. The evolution of robust vPLCs will make identifying and fixing vulnerabilities like these easier.

The development of vPLCs will also make it easier to virtualize more of the infrastructure to scale processes faster and with increased reliably across one or more facilities. When combined with better digital twins for representing physical equipment, it will also extend the concept of infrastructure as code to industrial automation.

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