Window CE Moves From Pocket to Control
Serious consideration of Microsoft Windows CE as an operating system for industrial applications began slightly over a year ago. First referenced in January 1997 Control Engineering, most mentions since have occurred in the last six months. In a short period of time, this real-time operating system (RTOS) has managed to focus attention on the little-known embedded RTOS market and has domi...
Serious consideration of Microsoft Windows CE as an operating system for industrial applications began slightly over a year ago. First referenced in January 1997 Control Engineering , most mentions since have occurred in the last six months. In a short period of time, this real-time operating system (RTOS) has managed to focus attention on the little-known embedded RTOS market and has dominated such industry gatherings as ISA '98 and the 1999 National Industrial Automation show at National Manufacturing Week.
Initially intended for consumer devices such as palm-sized computers and 'set-top box' web surfers, CE's benefits for manufacturing were recognized. Products soon began to appear-first for human-machine interface, then personal computer platforms.
As Windows CE evolves from version 2.x to 3.0 as a real-time
operating system, processing cycle time drops to about 1 msec. while
cycle variations decline to under 100
Will it do control?
PC-based control manufacturers were debating whether Microsoft Windows NT was a viable platform for control alone or required a real-time platform underneath (see CE , February 1999) when Windows CE appeared as a real-time alternative.
Is Windows CE a viable operating system for machine control applications? Most in the industry answer affirmatively. The debate really is between those who consider the current version 2.11 adequate and those waiting for a 'hard real-time' version, which some think will appear with version 3.0 projected for release fourth quarter 1999.
Host Engineering (Johnson City, Tenn.) developed WinPLC for Automationdirect.com (formerly PLC Direct , Cumming, Ga.) with embedded Windows CE version 2.1. Host president, Robert Oglesby, says that the finished product performed far better than even he expected. 'The vast majority of conventional controllers do not have near the operating system sophistication of Windows CE. Testing showed many aspects of program control to be far superior than the usual PLC and faster chips are coming for these embedded applications.
'The typical PLC has program scan time variations of several milliseconds. Our testing showed only 2 to 3 msec variations on a conventional PLC program running on the Windows CE box,' Mr. Oglesby continues. 'This platform will handle the majority of current applications controlled by PLCs.'
Think & Do Software (Ann Arbor, Mich.) developed the control software for WinPLC. The Windows CE version of the program was directly ported from Windows NT, which went quickly and without difficulty. Assembly machine oem, Innovative Metal Fabrication, has built a machine using WinPLC for its target market-personal computer assembly manufacturing-that has demonstrated the power of the system. Automationdirect.com's products were scheduled to begin shipment to customers in April 1999.
VenturCom (Cambridge, Mass.) provides tools to help developers create real-time applications for Windows NT and other platforms. Founder and chief technology officer, Myron Zimmerman, notes, 'We have done quite a bit of measurement of real-time determinism on Windows CE. Version 2.0 had some longer latency activity than early versions of 3.0, but that seemed mostly due to networking and video. While perhaps not fast enough for high-speed motion control, the platform is fast enough for most control applications.'
Xycom Automation (Saline, Mich.) has products scheduled for shipment in August or September 1999. Following the merger of Xycom and ASAP last year, Xycom Automation has begun to provide bundled solutions of hardware and software. The goal is to make purchasing and installing PC-based control similar to PLCs. Asic-300 software is being ported to Windows CE and bundled on several industrial PCs which will include Ethernet I/O and motion. According to the company, porting to Windows CE provides a smaller footprint than NT allowing it to run from ROM. This means the system can be diskless providing greater reliability than a typical PC.
Although the current version of Windows CE is capable of many machine control tasks, no one disputes that the next full version will be more deterministic. By reducing interrupt latency and increasing the number of priorities, version 3.0 will be almost as deterministic and fast as VenturCom.
Nat Frampton, president of Real-Time Development Corp. (Slidell, La.) has worked with Microsoft and OMAC (Open Modular Architecture Controller, a users' group) conducting tests of various CE versions. The figures show 'hard' versus 'soft' real time as a function of cycle speed plotted against variations of cycle time. His testing on a PC with an Intel x86 chip, shows version 2.x as soft real time. Version 3.0 can be considered hard real time in this definition given fast cycle times with little variation.
What has caused these improvements? Part of the answer is due to OMAC's efforts. Engineers affiliated with OMAC studied the necessary components for real-time control and proposed changes in the RTOS to Microsoft Corp. (Redmond, Wash.). Although Microsoft takes shots from the general computing press occasionally about not listening to customers, in this case it did listen and is still encouraging comments. OMAC's suggestions contributed significantly to specifications of version 3.0, which is slated for release by the end of 1999.
Significant new features for CE version 3.0 include:
32 priorities including nesting;
Timing behavior instrumentation;
Windows CE is made available to developers in components. Developers include only those components necessary to the operation of their device. Critics note this means users may not be able to run all application software available on every device-which is true. Although many industrial computer manufacturers are rushing to bring CE-based products to the market, it is really an embedded RTOS. This means it is intended for a specific application-like a programmable conroller or troubleshooting de-vice.
If the user wants or needs to run a variety of applications while doing control, then Windows NT should be considered. Users need to know the capabilities of a Windows CE device before buying and assure it meets the requirements of the application.
Until the publicity surrounding Windows CE, RTOS products were known primarily in the developer community. These operating systems have been around for quite some time controlling devices from the family automobile to cellular phones (see list for vendors). In fact, most users don't know what RTOS is used by their favorite PLC. Users really only care that the PLC is reliable.
An objection raised about Windows CE is the 256 KB memory footprint. While this may be small for Windows, most other RTOS products are much smaller-from 14 to 34 KB. Windows CE size may limit its use in some applications. It is important to know what the objective is before selecting an RTOS. There will be applications where the correct answer is another RTOS.
Another objection raised is that although a strength of Windows CE lies in use of Win32 APIs, it supports only about a third of them, and others are not the same. Microsoft's Regis Bridon, product manager for Windows CE core OS, reports that CE supports about 1,800 APIs. He says many functions are not used because the embedded nature of the OS doesn't require them, while some redundant APIs are not supported, once again to save space.
Why use Windows CE
Why use a Windows CE platform for control? Nick Kayes, softlogic marketing programs manager at Intellution (Norwood, Mass.), says, 'The leading reason is scalable solutions from work cell to supervisory system. Programmers can have user defined function blocks across platforms and use the same editors. Another plus is data portability and the ability to use push technology going to the MES [manufacturing execution system] layer.'
One way of implementing Windows CE in control applications is to use its data handling and open API strengths with traditional control platforms. GE Fanuc Automation (Charlottesville, Va.) has announced a version of CNC with CE embedded. John Turner, manager of CNC open systems, says, 'GE Fanuc's new ' i S' CNC integrates PC functionality on the backplane. The PC handles data, HMI, and communications. Benefits of using CE include open standards and ROMable operating system that eliminates hard drives and provides quick start up. Over the next two years, CE will have a big impact on the cost of CNCs with embedded software, allowing manufacturers to use less expensive hardware like PC/104.'
At the mention of Windows CE, perhaps the most-common devices that come to mind are palm-sized computers that fit in a shirt pocket. The industrial market is not immune from the 'pocket' revolution. Rockwell Automation (Milwaukee, Wis.) has PocketLogix, a tool running on small Windows CE pocket computers for maintenance personnel to easily carry for troubleshooting. GE Fanuc Automation's PocketView is a wireless handheld pocket PC with a version of Cimplicity HMI enabling a peek into the workings of a machine. Iconics (Foxborough, Mass.) has Pocket GraphworX and, soon, Pocket ControlWorX. Who knows what technicians will carry in their pockets next?
Ready for control?
Very bright and knowledgeable engineers differ on whether the current version of Windows CE is a good platform for machine control. Some who are convinced it is will be first to the market with products. Other companies will wait for the more deterministic version. One thing is for sure, control suppliers are evaluating the operating system and making plans. Windows CE will definitely become an option for machine control.
The Linux alternative
Linux is another hot operating system. Linus Torvalds wrote a kernel based on the venerable and stable Unix operating system but published the source code-called Open Source. Developers around the world send fixes, changes, and upgrades to Mr. Torvalds, who updates the central copy. This system of development treats the operating system as a living, evolving organism. The other fascinating thing about Linux is the price-free.
The hot market for Linux currently is in enterprise servers. This is not surprising given the Unix heritage. But who would imagine a Unix-type OS for real-time machine control?
Victor Yodaiken, professor of computer science at New Mexico Institute of Technology, wrote a real-time kernel to work with Linux. Zentropic Computing (Herndon, Va.) used the kernel along with Linux to develop a real-time operating system. Zentropic uses it in difficult real-time applications such as flight simulation. No machine control products exist, yet, but the National Institute of Standards and Technology has developed a robotic control system with the operating system using OMAC open computing standards.
Jim Norton, Zentropic ceo, says he wanted to have some control over his destiny by using open-source Linux. Other operating systems, like Windows, subject him to the whims of another company. A change to the OS could cause major system changes, often difficult to convey to customers and costly to fix. With open-source software, Zentropic programmers can edit the operating system code to fix a problem considerably more quickly than waiting for a new revision from someone else. Mr. Norton adds that Linux has proven to be a very stable platform for control.
Windows CE product announcements have dominated industrial trade shows for the past year much to the expense of Java. Will Linux prevail on technical merits without a major marketing and support organization? Or will it be a niche player? It definitely will provide some interesting alternatives for controls designers.
Windows CE and RTOS Suppliers
Announced control products based on Windows CE to be shipping by the end of summer 1999:
Automationdirect.com (WinPLC, Cumming, Ga.)
CamSoft (MTC3000, Lake Elsinore, Calif.),
GE Fanuc Automation (iS CNC, Charlottesville, Va.)
Iconics (PocketControlWorX, Foxborough, Mass.)
ObjectAutomation (OAenterprise,Santa Ana, Calif.)
Phoenix Contact (Remote Field Controller, Harrisburg, Pa.)
Wonderware (InControl, Irvine, Calif.).
Xycom Automation (OpenCntrl, Saline, Mich.)
These companies have announced or are showing products, but are waiting for version 3.0 before shipping:
Intellution (Norwood, Mass.)
MDSI (Ann Arbor, Mich.)
Rockwell Automation (Milwaukee, Wis.)
Schneider Electric (North Andover, Mass.)
Siemens Energy & Automation (Alpharetta, Ga.)
Steeplechase Software (Ann Arbor, Mich.)
There are other real-time, embedded operating systems. Here are some of the vendors:
Altersys (Longueuil, Quebec, Canada)
Enea OSE (Taüby, Sweden)
Imagination Systems (Beaverton, Ore.)
Integrated Systems (Sunnyvale, Calif.)
Lynx Real-Time Systems Inc. (San Jose, Calif.)
Phar Lap (Cambridge, Mass.)
QNX Software Systems (Kanata, Ontario, Canada)
Radisys (Hillsboro, Ore.)
Sun Microsystems Inc. (Mountain View, Calif.)
Wind River Systems (Alameda, Calif.).
No RTOS achieves a wide market without a supply of development tools. Companies that have development tools for Windows CE systems include:
Arcom Controls (Cambridge, U.K., Kansas City, Kan.)
Blue Water Systems (Edmonds, Wa.)
Bsquare (Bellevue, Wa.)
Eclipse International (Santa Rosa, Calif.)
Intrinsyc Software (Vancouver, British Columbia, Canada).