Virtual Controllers for EtherCAT Networks
Leveraging acontis’ extensive expertise in EtherCAT and hypervisor technology enables the virtualization of EtherCAT controllers. Virtual controllers for EtherCAT can be directly connected to EtherCAT networks using EtherCAT Direct Mode, or, with the EtherCAT Open Mode Feature Pack (EOM), utilize EOM to control remote EtherCAT network segments over conventional switched Ethernet IT networks.
Virtual EtherCAT controllers optimize hardware usage by leveraging high-performance, commonly available platforms that can host multiple EtherCAT MainDevices, maximizing both performance and sustainability while ensuring efficient use of available hardware resources.
Figure 1: Virtual controllers can share common hardware while independently controlling separate networks.
By combining the acontis EC-Master with hypervisors such as the acontis real-time hypervisor RTOSVisor, or soft real-time hypervisors like Proxmox, new opportunities emerge for creating factories where Information Technology (IT) and Operational Technology (OT) networks seamlessly integrate. This allows EtherCAT-based machinery to be directly controlled from the IT server room, eliminating the need for specialized gateways.
Virtual Controllers with EtherCAT Direct Mode
Virtual controllers offer an optimized approach to controlling complex machinery with multiple EtherCAT networks.
Applications might be multi-axis motion or robots as well as measurement and data acquisition systems – as the flexibility of hardware resources in combination with the possible direct data-exchange within the controller-system can boost overall performance.
Figure 2: Two Virtual MainDevices controlling two independent EtherCAT networks using Direct mode
Software Architecture
The EC-Master is operated in multiple virtual machines – according to the number of controlled EtherCAT segments. To achieve best performance in EtherCAT direct mode, the network layers of the operating systems and hypervisor are bypassed:
- The hypervisor provides direct access to defined Ethernet hardware for each virtual machine using pass-through technology.
- The acontis real-time Ethernet drivers are used within the virtual machines to directly access the defined Ethernet hardware.
In the figure below, an additional Ethernet hardware is used in virtualized / shared mode for all virtual machines to provide standard TCP/IP data exchange – e.g. for remote access, configuration and diagnosis.
The EC-Master instances are set up similar to classic EtherCAT controller, no specific adoptions are necessary when standard real-time OS like RT-Linux or VxWorks and standard Ethernet Hardware are used.
Figure 3: Software architecture for two virtual EtherCAT MainDevices on one System for maximum performance via EtherCAT Direct Mode with direct hardware access.
Benefits
Compared to multiple physical controllers, virtual controllers provide several key benefits:
- Optimized Hardware Usage: Traditional controllers are often oversized for their specific tasks, resulting in unnecessary use of space, energy, and maintenance. Virtual controllers address this by utilizing optimized hardware for precise requirements, reducing oversizing caused by worst-case planning or standardization.
- Improved System Performance: In systems using multiple controllers, communication between them (e.g., through EtherCAT Automation Protocol) is necessary. Virtual controllers simplify this with controller-internal virtual networks, offering diverse options for inter-controller communication such as file exchanges, streams, or shared variables, depending on the OS or hypervisor used, resulting in more efficient and faster data exchange.
- Optimal Hardware for Specific Use-Cases: Virtual controllers can combine multiple controllers into a single unit, saving space and allowing the use of highly robust hardware with additional functions like Human-Machine Interfaces (HMI).
- Reduced Costs and Maintenance: A single hardware unit running multiple virtual controllers reduces total cost of ownership (TCO). Even with increased performance, the cost per controller is generally lower compared to traditional physical controllers. Additionally, maintenance is simplified with modern IT tools that allow for remote management, reducing the need for on-site support.
Virtual controllers using EtherCAT Direct Mode with real-time capable operating systems and hypervisors can match traditional EtherCAT controllers in performance, offering simple configuration, easy diagnostics, and and maximum performance with extremely fast cycle times with minimal jitter.
Virtual Controllers with EtherCAT Open Mode
Virtual controllers offer an optimized approach to controlling complex machinery with multiple EtherCAT networks.
Figure 4: Two Virtual MainDevices controlling two independent remote systems using EtherCAT Open Mode.
Software Architecture
Same as the virtual controller using EtherCAT direct mode, the EC-Master is operated in multiple virtual machines.
However, to achieve maximum flexibility, this setup makes use of a shared Ethernet hardware for all EtherCAT MainDevices:
- The acontis EtherCAT Open Mode Layer enables the transport of the EtherCAT frames via the switched IT network – using RAW or UDP communication methods.
- The acontis Ethernet drivers are using the standard OS and hypervisor network stacks to access the shared Ethernet hardware.
- The hypervisor provides access to a shared Ethernet hardware for all EtherCAT Main Devices.
In this example, we see a second Ethernet hardware which is shared to all virtual machines for all other TCP/IP communication.
The EC-Master instances differ from classic EtherCAT controller setup, as the EtherCAT Open Mode Layer is used and the acontis Ethernet drives do not directly access the Ethernet hardware but use the underlying OS / hypervisor network stack.
This setup provides maximum flexibility, as additional virtual machines can simply be added without any hardware modification but comes with some limitations in regards to minimal EtherCAT cycle time.
Figure 5: Software architecture for two virtual EtherCAT MainDevices on one System for maximum flexibility via EtherCAT Open Mode using shared Ethernet access.
Benefits
Combining EtherCAT Open Mode (EOM) with Virtual Controller technology adds even greater advantages:
- Enhanced Reliability: EOM allows virtual controllers to operate within a secure IT environment, such as an IT server room, safeguarding them from risks associated with physical environments and extending system lifespan.
- Protection from Environmental Factors: Placing controllers in secure IT environments protects them from issues like vibration, temperature fluctuations, and EMI. Controllers also benefit from IT infrastructure such as backup power and continuous supervision.
- Prevent Unauthorized Access: IT server rooms provide protected access to virtual controllers, eliminating risks of direct physical manipulation that exist in machinery cabinets where USB ports or other service interfaces are exposed.
- Cybersecurity: Hosting machine controllers in a secure IT environment enhances their resilience to cyberattacks by leveraging well-established IT cybersecurity practices.
However, virtual controllers using EtherCAT Open Mode may face certain differences compared to Direct Mode, such as increased jitter for UDP/RAW communication and more complex configuration due to the use of standard IT networks. Despite these challenges, EOM remains a powerful option for securely and efficiently controlling remote EtherCAT segments.
For more information about EOM, check out our blog article, "What is EtherCAT Open Mode?" and to learn more about how EOM can be implemented with EC-Master, check out the webpage for our EC-Master EOM Feature Pack.
Solution from acontis for Virtual Controllers
acontis offers all the essential software components needed to create Virtual EtherCAT Controllers tailored to your requirements:
- EtherCAT MainDevice Software: The acontis EC-Master is a field-proven EtherCAT MainDevice Software, combining a comprehensive feature set with high performance and low resource requirements. It supports control of multiple networks from a single installation, and seamless operation within hypervisors and virtual machines.
- EC-Master EtherCAT Open Mode Feature Pack: The EOM Feature Pack adds all necessary functions to enable EtherCAT Open Mode, allowing the use of standard IT networks to control remote EtherCAT networks from a central EtherCAT Controller
- Hypervisor: Depending on your application requirements, the following options are available:
- acontis hard Real-time Hypervisors: Provides maximum performance with the lowest cycle times and jitter, ideal for high-performance virtual EtherCAT controllers using EtherCAT Direct Mode.
- Soft Real-time Hypervisors: acontis provides documentation and guidance on using soft real-time hypervisors like Proxmox, commonly used in IT environments, to create Virtual Controllers – especially for centralized Virtual Controllers using EtherCAT Open Mode.