CNC Faceoff: PC Platforms with Virtualization

Computer numerical control (CNC) systems based on multi-core processor systems can run applications on real-time operating systems (RTOS) in multiple cores, while maintaining coordination and communication among segments of the application. It offers flexible price/performance options for future CNC machine designs.


The Biesse Rover Gantry machine’s HMI runs Microsoft Windows. Courtesy of TenAsysThe CNC (computer numerical control) machine market is ultra competitive. To offer more value to customers, machine vendors carve out specialty niches and push machines to new heights of productivity per dollar invested. With each generation of machine, CNC vendors can decide which technologies to develop and refine to differentiate their machines from others. Standard PC platforms offer the highest versatility and performance per dollar, and many CNC suppliers design and build machines using PC-based architecture to provide competitive advantages.

User interface appearance, usability, and flexibility are areas of intense competition among proprietary developments. Making machines easier to use has a direct correlation with improving productivity and accomplishing product differentiation in specific applications. For many CNC vendors, human-machine interfaces (HMIs) are implemented using Microsoft Windows operating system. These include:

  • Biesse S.p.A. of Pesaro, Italy, for its Rover line of CNC machines used to make components for furniture and cabinetry items (Figure 1)
  • Cleveland Motion Controls (CMC) of Cleveland, Ohio, focusing on plasma cutting
  • Anca Motion Pty. Ltd. of Bayswater, North Victoria, Australia, addressing applications including laser cutting, water jet cutting, and tool grinding.

CMC’s Burny Phantom is an integrated package featuring PC-based numeric control, 2 or 3 axis drive amplifiers and a Microsoft Windows-based operator console. Courtesy of TenAsysAll three machine tool original equipment manufacturers (OEMs) augment Microsoft Windows with other software tools.

Real-time requirements

CNC machines are some of the most complex systems in the manufacturing world. Even the simplest CNC machines may have four motors driving motion axes that must move synchronously, at high speed, with very high precision. Control software orchestrates the motion, making new decisions on how the motion axes must move and establishing a new target position every one or two milliseconds. In addition, some machines incorporate a fieldbus machine network, and because of high precision timing and oversampling requirements of some fieldbus interfaces (such as EtherCAT), the cycle times of control loops that manage these need to be as short as 100 microseconds.

Anca Motion expects to migrate from dual to quad-core processors to provide new functionality, such as online simulations of cutting or grinding operations. Courtesy of TenAsysMicrosoft Windows is not designed to manage all these control tasks simultaneously and guarantee that they will be processed with predictable timing (determinism), so most high-speed machines run their control loop software on real-time operating systems (RTOS).

Running two operating systems (Microsoft Windows and an RTOS) on the same platform poses technical challenges that has caused some CNC machine vendors to incorporate separate computing platforms, one for real-time control functions and another to manage the HMI. Multiple computers increase complexity and cost, reduce reliability, and add cost to the end customer. The three CNC technology suppliers mentioned run the RTOS and Microsoft Windows on the same platform.

Dual-core processor in the Biesse computer runs Microsoft Windows on one core and the Intime RTOS on the other core. Courtesy of TenAsysWhile software technologies that enable multiple operating systems to coincide on the same computing platform have existed for a long time, construction of multi-OS platforms has received a boost with the advent of multi-core processing units.

Anca Motion has had a philosophy of using one CPU for the CNC and the operator interface, but with the introduction of multi-core CPUs, the option to use a lower powered but dual core processor became available. While the new design requires a change in system architecture, company engineers wanted to add functionality and performance without increasing system costs. Choosing an energy efficient, dual-core processor saved cost while consuming less power than other multicore processor chips, generating less heat, which lowers the complexity and cost of cooling the system electronics. That helps Anca Motion customers, who will use the products in warm climates.

Embedded virtualization

Key to combining OS environments is embedded virtualization – the ability of one computer system to partition processing to present separate native processing environments and input/output (I/O) hardware resources for exclusive and directed use to different operating systems that co-reside in the system. With embedded virtualization, each OS thinks that it has full control of the processor. Unlike server virtualization environments, such as VMware, that support multiple OSs but are not designed to handle real-time events, embedded virtualization techniques enable CNC applications to run multiple OSs without sacrificing determinism.

Embedded virtualization enables dual-core processors as used in the Biesse system to support two operating systems by dedicating one CPU core to the RTOS and one to Microsoft Windows (see Figure 4). The CPU instruction cycles of the RTOS core are available 100% for the real-time applications, while the CPU cycles of the remaining core become the exclusive property of a Microsoft Windows virtual machine.

The two processor cores communicate by using the RTOS’s built-in inter-process communication mechanisms implemented via shared memory. This eliminates the need to develop proprietary code for the RTOS and Microsoft Windows applications to pass information to each other. Using this technique, real-time interrupt latencies are reduced by an order of magnitude compared to Microsoft Windows alone, from 10-30 microseconds down to 1-3 microseconds.

Loop cycle times in the 50-200 microsecond range can operate with high precision and accuracy. The result is a significant improvement in the quality and bandwidth of control algorithms that can be deployed on a real-time Microsoft Windows platform.

Use of shared memory is only one implementation detail of the embedded virtualization support provided by the RTOS for Microsoft Windows environment. INtime also directs hardware interrupt functions of I/O devices to ensure that user interface events, such as key presses on the operator touch screen, do not interrupt real-time tasks, such as controlling the CNC machine’s cutting motors.

Anca Motion’s designs also take advantage of RTOS support for standard high-performance network interfaces, such as industrial Ethernet protocol, for connecting to motor drives and I/O modules. Some industrial Ethernet supports deterministic high bandwidth communications (100Mb/sec) and requires RTOS support to ensure that the protocol’s timing requirements are met. Using commodity Ethernet hardware is another factor that helps Anca Motion’s customers keep machine cost under control while improving performance.

PC-based architectures

Tightly linking real-time and Microsoft Windows environments, CNC technology suppliers have a growth path by which they can add new features in future iterations of CNC products. For example, CMC Controls is considering porting the software-based PLC run-time engine to execute on the RTOS kernel to increase system throughput.

CNC manufacturers that have embraced multicore technology can also look forward to scaling their systems as the number of processor cores provided by chip manufacturers increases in the future. The Anca Motion engineers expect to upgrade their system from dual to quad-core processors to provide new functionality, such as online simulations of cutting or grinding operations.

Users can expand their applications beyond single processor systems and run RTOS applications across several cores, while maintaining coordination and communication between segments of the application via global objects. Doing so will enable future CNC machines to offer an appropriate number of processor cores to match required price and performance needs.

Technology review: RTOS + Microsoft on one PC

  • TenAsys’ INtime RTOS has been used to add a real-time operating system (RTOS) to Microsoft Windows systems for more than a decade.
  • Anca Motion selected the dual-core Intel Atom processor, saving cost, and energy; the Atom processor consumes less power than other multicore processor chips, generating less heat.
  • INtime offers real-time support for standard high-performance network interfaces, such as EtherCAT (an industrial Ethernet protocol) for connecting to motor drives and I/O modules. EtherCAT supports deterministic high bandwidth communications (100Mb/sec) and requires RTOS support to ensure that the protocol’s timing requirements are met.
  • TenAsys INtime for Windows RTOS offers a global object networking facility called GOBSnet, which enables running RTOS applications across several cores, while maintaining coordination and communication between segments of the application via global objects.

Kim Hartman is vice president of marketing and sales of TenAsys.

The Top Plant program honors outstanding manufacturing facilities in North America. View the 2015 Top Plant.
The Product of the Year program recognizes products newly released in the manufacturing industries.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
Pipe fabrication and IIoT; 2017 Product of the Year finalists
The future of electrical safety; Four keys to RPM success; Picking the right weld fume option
A new approach to the Skills Gap; Community colleges may hold the key for manufacturing; 2017 Engineering Leaders Under 40
Control room technology innovation; Practical approaches to corrosion protection; Pipeline regulator revises quality programs
The cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Power system design for high-performance buildings; mitigating arc flash hazards
VFDs improving motion control applications; Powering automation and IIoT wirelessly; Connecting the dots
Natural gas engines; New applications for fuel cells; Large engines become more efficient; Extending boiler life

Annual Salary Survey

Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.

There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.

But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.

Read more: 2015 Salary Survey

Maintenance and reliability tips and best practices from the maintenance and reliability coaches at Allied Reliability Group.
The One Voice for Manufacturing blog reports on federal public policy issues impacting the manufacturing sector. One Voice is a joint effort by the National Tooling and Machining...
The Society for Maintenance and Reliability Professionals an organization devoted...
Join this ongoing discussion of machine guarding topics, including solutions assessments, regulatory compliance, gap analysis...
IMS Research, recently acquired by IHS Inc., is a leading independent supplier of market research and consultancy to the global electronics industry.
Maintenance is not optional in manufacturing. It’s a profit center, driving productivity and uptime while reducing overall repair costs.
The Lachance on CMMS blog is about current maintenance topics. Blogger Paul Lachance is president and chief technology officer for Smartware Group.
The maintenance journey has been a long, slow trek for most manufacturers and has gone from preventive maintenance to predictive maintenance.
This digital report explains how plant engineers and subject matter experts (SME) need support for time series data and its many challenges.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.
Maintenance Manager; California Oils Corp.
Associate, Electrical Engineering; Wood Harbinger
Control Systems Engineer; Robert Bosch Corp.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me