Selecting a Microsoft Windows Operating System

Transcription

1 . Rockwell Automation Automation Control & Information Group Industrial Computer Business (ICB) Selecting a Microsoft Windows Operating System for an Industrial Application Tips on choosing what Windows operating system to use in industrial applications. Revision 4.0

2 Windows Operating Systems: Which one to use? This paper attempts to clarify the position of Windows operating systems used in industrial computing applications. Table of Contents I. Introduction II. Desktop Operating Systems Windows 9x/NT/2000 a. Applications and differentiating features b. Windows 95/98 specifics c. Windows NT/2000 specifics III. Embedded Operating Systems Embedded NT and Windows CE a. Applications and differentiating features b. Embedded NT specifics c. Windows CE specifics IV. Computers and Operating Systems in Industrial Applications a. Application Requirements b. Network Connectivity c. Computer Performance d. Software Scalability e. Future Growth V. Summary Appendix A. Operating System Selection Chart Page Rockwell International

3 Introduction What everyone needs to know about choosing a Windows operating system in industrial computing applications. Computer technology is being used in an ever-growing number of personal, commercial, and industrial applications. Many of these applications are based on some type of Microsoft Windows operating system. Microsoft products have become de facto standards in the personal computing market segment. The look-and-feel of their common graphical user interface, together with the ease-of-use features, have been increasingly in demand in other computing segments as well. This paper examines the Microsoft desktop computer and embedded computing operating systems with respect to industrial applications. Microsoft s desktop computer operating systems include Windows 95/98 and Windows NT / Microsoft s embedded operating systems are Embedded NT and Windows CE. Each operating system is targeted at a specific computing application. It is important to understand the differences between each operating system when selecting one for an industrial computing application Rockwell International Page 3

4 Desktop Operating Systems Windows 95/98, NT, 2000 Operating Systems When someone mentions a personal computer, the image that comes into most people s minds is the standard desktop PC box with separate monitor, keyboard, and mouse. Since IBM released the PC in 1980, Intel and Microsoft have helped transform it from a simple office productivity tool into a multifunctional personal computing and communication device. The majority of today s personal computers contain some type of Intel processor and Microsoft Windows operating system. Applications The applications for a personal computer are quite varied. The PC is used in business for communications, accounting, product design, and personal productivity tools. It is used in industry to control and monitor plant operations, run machinery, and to collect factory floor data for regulatory documentation and process analysis. Graphic artists and musicians for composition and editing use the PC. It is used by students for research, analysis, and writing, and by almost everyone in personal leisure activities, including Internet browsing, video games, and hobbies. The Microsoft Windows desktop operating systems contain a rich feature set to support these varied applications. The feature list includes legacy support for older hardware platforms, built-in debugging and help, Plug&Play support for a wide variety of hardware (all the drivers needed to support each vendor s hardware), networking with a number of different protocols, and a highly integrated environment for applications and Internet connectivity. Differentiating Features The Microsoft desktop operating systems features target either the personal PC market (Windows 95/98) with their simplicity and multimedia support or the business PC market (Windows NT/2000) with their networking and communications capabilities. Because so many features are integrated into the desktop operating system, quite a large amount of computer mass memory is required to store it. A standard Windows NT installation requires at least 500Mbytes of hard drive space to complete the installation. Customized installations can reduce the runtime memory footprint somewhat, but most Page Rockwell International

5 desktop operating systems require a hard drive in the computer system to hold the operating system and applications. The desktop PC operating systems typically require an Intel architecture CPU, at least 32MB of RAM memory, and a 500MB to 1GB hard drive. Today s CPUs require a large amount of power and generate a significant amount of heat, so a large power supply and cooling fan are also required. While this configuration is a very powerful computer system, it has some weaknesses with respect to factory applications. Both the hard drive and cooling fans are mechanical devices, subject to wear over time. Typical MTBF numbers for the best hard drives and fans are 50,000 hours in a factory environment. Because the hard drive is the core of a computer, its failure must be expected and planned for with proper system back-ups or redundant drive systems. The alternative to a rotating hard drive is solid state flash memory. However, large capacity flash memory is currently cost prohibitive in the 500MB to 1GB sizes required for desktop PC operating systems. The desktop PC has evolved into a very standardized computer product. It is easily scalable in memory size, CPU power, and peripherals. A typical PC system can be enhanced to handle new or additional applications requiring more processing power. This is an advantage in industrial applications when the user wants the flexibility for future upgrades. However, computer technology evolves very quickly, and product life cycles are short. Consequently, by the time the need for an upgrade arises, upgrading may no longer be a realistic or cost-effective alternative to replacement. For example, three years ago most computers used SIMM memory modules. Today, DIMM modules are dominant, the migration path is toward RAMBUS, and the availability of SIMM memory for upgrades is limited. There are a large and ever-growing number of software applications available for standard Windows desktop operating systems. These applications speed up and simplify project developments and increase productivity. The disadvantage to this widely open environment is keeping unauthorized applications off of factory floor computers. These types of applications reduce productivity and can introduce computer viruses into a company s networks. For a typical industrial computing application, many of the Microsoft Windows desktop operating system features are not required. Human Machine Interface (HMI) applications make use of Windows multimedia and graphics support. Soft control applications make use of Windows NT communications and system security. However, the availability of all the many features in a desktop operating system facilitates the addition of new applications and the upgrade of existing ones. Most of today s industrial software products have development packages that run on the same Windows operating system as the runtime product. Therefore, an industrial computer running a Windows desktop operating 2000 Rockwell International Page 5

6 system can support both the runtime and development environment. Customers can develop and modify their application without needing a separate programming device. Windows 95/98 Microsoft s Windows 95 and Windows 98 operating systems are targeted at the personal PC market and single user business environments. Microsoft has implemented many features to simplify the user interface and operation. These include Plug&Play, where added hardware is automatically detected and configured with integrated drivers, and extensive help files to diagnose problems. When used on the factory floor, Windows 95/98 operating systems are fairly easy to configure and manage. However, many industrial software applications are focusing more on Windows NT systems, because of the more robust OS kernel, security, and extensive networking support, which equates to more uptime. Windows 95/98 operating systems may not be robust enough for critical industrial and networked applications. Windows NT/2000 Microsoft s Windows NT and Windows 2000 operating systems are targeted at networked business environments. These operating systems are available for client (Windows NT 4.0 Workstation, Windows 2000 Professional) and server (Windows NT 4.0 Server, Windows 2000 Server) applications. The client operating systems are for individual workstations, whereas the server operating systems are for the network and data server computers required for a highly networked office environment. Microsoft has implemented a number of features to support these environments, including extensive network support, information sharing capabilities, and client/server communication features. Windows 2000 also includes a number of Windows 98 features like Plug&Play and extensive help files to simplify configuration and user operation. Windows NT has become the most popular factory floor operating system. This is due mainly to its robust operation, security features, and networking capability. Many industrial software applications focus on Windows NT as their preferred platform. The one drawback of Windows NT is it is more difficult to configure and manage than Windows 9x operating systems. Because Windows 2000 is easier to configure and support, it is expected that most industrial applications will migrate from NT to 2000 as vendors release their Windows 2000 product versions. Page Rockwell International

7 Embedded Operating Systems Embedded Windows NT and Windows CE Operating Systems While the desktop PC is the most identifiable form of computer, there are a much greater number of embedded computing devices in use today. Cell phones, personal information devices, video games, and even pagers are examples of commercial devices with embedded computer operating systems. Programmable logic controllers (PLCs), loop controllers, dedicated operator interface devices, and smart valves are examples of industrial devices that use embedded operating systems. Embedded operating systems are small, scalable products used by engineers to develop many microprocessor-based products on the market today. The main advantage of an embedded operating system is its very small footprint (memory size), so embedded products do not typically require a hard drive to operate. Scalability and portability are also important, so the operating system can be custom tailored for the specific product needs. Microsoft has responded to the increased need for connectivity and information sharing between classic embedded computing devices and business computing environments, by developing two Windows-based embedded operating system products: Embedded NT and Windows CE. These embedded operating systems use the same Windows graphical user interface made popular by Microsoft s desktop operating systems. They also contain many networking features to support the growing need for connectivity. These new embedded operating systems bridge the gap between traditional stand-alone embedded operating systems and highly connected desktop PC operating systems. Applications The applications for a Windows embedded operating system range from personal organizers to industrial control systems. Any device containing a microprocessor can potentially use an embedded operating system. Microsoft s embedded operating systems are used in a variety of personal productivity tools like Handheld PCs, Pocket PCs, and Internet telephones. They are also used in embedded applications for Internet kiosks Rockwell International Page 7

8 Differentiating Features Size and scalability are the biggest differentiators between a desktop and embedded operating system. A Windows desktop PC uses a hard drive for main storage, so memory size is not a design consideration. Embedded operating systems have very small memory footprints, and use small solidstate memories. The typical Windows desktop PC uses the standard Microsoft install, so scalability is not too important. While Microsoft allows for some configuration during installation, eliminating some features do not greatly change the required storage memory. Embedded operating systems can be highly scalable, so only OS features needed for a product s functionality is selected. For example, if a product does not have a display, then all parts of the OS that support graphical interfaces can be removed to reduce the overall memory storage requirements. Embedded operating systems are typically runtime only environments. All user application development must be done on an external programming device, typically a desktop PC. This is because embedded devices have limited memory storage capability, and most Windows-based development programs are very large and require a large amount of storage for online help and information files. Because of their application-specific nature, there are not a wide variety of open or multi-platform software products available for embedded operating systems. Embedded NT supports standard desktop PC applications, because it is a variant of Windows NT4.0 and runs only on PC architectures. Windows CE software applications are developed specifically for that operating system, and must be compiled and tested on each hardware platform to ensure they operate properly. Embedded NT The Microsoft Embedded NT operating system is a configurable, componentized version of its Windows NT 4.0 desktop operating system. Embedded NT can fit into as little as 6MB flash ROM or disk space, depending upon the NT features selected. It requires a minimum of 24MB RAM. However, like NT 4.0, Embedded NT requires a powerful Intel architecture processor, and only runs on ISA/PCI based hardware platforms. Embedded NT does not have deterministic interrupt handling, supports symmetrical multi-processing (SMP), uses FAT32 or NTFS file systems, and offers pretty much the same security and I/O support as NT 4.0. A development kit is available for customers and vendors who want to create a standard, fixed application environment. Once all the target applications and the required NT features are identified, a fixed image is created and loaded onto the target computer device. The advantages of Embedded NT include a familiar and proven NT4.0 technology in a smaller footprint memory that can possibly be loaded into Page Rockwell International

9 solid state memory. The disadvantage is no field installation or expansion support no new applications can be loaded onto the computer without creating a new image with the development kit. Microsoft is targeting mid to high-level applications with its Embedded NT simplified computer-like interfaces for communication and information. Windows CE The Microsoft Windows CE operating system is an embedded operating system for the new generation of highly connected 32-bit devices. Windows CE combines Windows compatibility with real-time support to deliver rich, scalable open foundation for building a wide variety of products. Windows CE is a true embedded operating system that can be customized to fit each unique hardware platform. Its modular nature allows product developers to include only those features required for their product to achieve a compact platform that integrates seamlessly with Windows and the Internet. Economical solid-state flash ROM can be used instead of a mechanical hard drive for Windows CE mass memory. CE fits in as little as 400KB ROM, needing at least 1MB for graphics support. Only 40KB of RAM is needed, although more memory is required to support applications. CE runs on a variety of microprocessors, so is not restricted to Intel x86 architectures. It supports a large subset of desktop PC I/O, including keyboards, serial and parallel ports, Ethernet, USB, PCMCIA, sound, infrared, and flash disks. All these embedded OS features allow Windows CE to be used on targeted hardware platforms designed for a unique application. The typical Windows CE industrial product is a 100% solid state device. It uses a low power RISC or x86 microprocessor, eliminating the need for cooling fans. It contains flash ROM, so no rotating hard drives are required Rockwell International Page 9

10 Computers and Operating Systems in Industrial Applications When deciding upon an open platform computer system for an industrial application, there are a few trade-offs that need to be considered. The application requirements need to be determined, as well as networking, performance, and future enhancement needs. These answers will help decide if the application is better suited for either an embedded or desktop PC operating system. Application Requirements Most industrial computing applications can be segmented into humanmachine interface (HMI), control, and information management. HMI applications are typically graphical operator interface terminals, as well as programming / debugging workstations for embedded control devices. Control applications encompass soft programmable logic control, process control, and motion control. Information management is a catchall for data acquisition, storage, and data sharing between the factory floor and business systems. A typical industrial application can include one or more of these segments. HMI applications range in size from simple dedicated operator interface terminals to full-blown factory supervisory PC workstations. A Windows CE based computer offers an alternative to dedicated or proprietary operator interface products. A Windows CE based computer can provide functionality similar to what is available from most proprietary operator terminals, while offering the advantages of the Windows standard look-and-feel, greatly increased configurability, and a wider range of communication options. A desktop operating system may be required for large operator interface applications, particularly those with a large amount of data collection requirements. PCs with hard drives provide significantly more storage space than an embedded computer product with flash ROM. However, even in larger HMI applications, CE based computers can play a role. Configured minimally as thin clients, they can be inexpensively deployed to provide multiple windows into the application throughout the site. Control applications based on open platform computers are becoming more common. Most of today s soft control applications run on standard desktop operating systems, which by themselves do not provide much in the way of real time scan rates or interrupt handling and may have to be supplemented by Page Rockwell International

11 real-time kernels. While some control applications do not require millisecond determinism, many need it to ensure proper operation. Accordingly, many applications have until now been run on expensive and complex hybrid systems. Windows CE based computers can now provide less expensive alternatives. Windows CE 2.12 provides some level of real-time control, and is suitable for small scale control applications involving no more than 10 tasks, where response times within 1 millisecond are adequate. The new Windows CE 3.0 version offers hard real-time determinism. It is able to handle control applications with many more tasks and provide response times in the order of 100 microseconds. Because Windows CE 3.0 is so new, it will take time for software vendors to port their control packages to it, but it is expected to play a significant role in control. Information management applications are typically based on desktop operating systems, because such systems support superior data management, networking, and large storage devices. There is also an abundance of information-related software applications available for desktop PCs. While Windows CE based computers do not have the resources needed for such applications, they can have a role to play as auxiliary devices, similar to the role they can play in large HMI applications. As thin clients, they can provide multiple data input and display stations in an economical and easy to manage fashion. Because Windows-based PCs have been around for over 10 years, today s industrial software products mainly run on desktop operating systems. However, with the advent of Windows CE, many new and existing software products are being ported to the CE environment. Because CE does not offer the same performance or features as the desktop operating systems, CE-based industrial software will typically have a reduced or refined feature set than similar PC-based versions. Connectivity Network connectivity is also an important consideration for industrial applications. Connectivity includes communication with factory floor control devices (PLCs, barcode scanners, and sensors), as well as networking back to a higher level computer or information system. Both desktop and embedded operating systems support a variety of Ethernetbased network protocols with internal drivers. Factory floor control networks, like DeviceNet, ControlNet, or Profibus, require special interface cards. These interfaces have traditionally been ISA or PCI cards, which plug into a PC backplane, with vendor-specific drivers for desktop operating systems. Embedded products may use integrated interfaces to support factory networks, or have a PCI, PCMCIA, or PC104 type expansion board interface. It is important to make sure there are specific drivers for the target operating system, for each network card required. Performance 2000 Rockwell International Page 11

12 Desktop PCs are based on high performance Intel architecture CPUs. As of this writing, the typical PC has a Pentium III 600MHz processor, and highend systems are available with multiple processors up to 1GHz. Pentium IV processors with clock speeds starting in the 1.4GHz range will start appearing in the commercial marketplace around the end of the year Embedded computing products typically have some type of low power RISC processor. While these 32-bit processors provide an adequate amount of performance for their embedded task, they are not designed to provide desktop PC performance when loaded down with multiple applications running simultaneously. Desktop PCs are also designed for fairly simple upgrades, so a faster processor can be installed if more performance is required. Embedded products typically do not offer CPU upgrade capability, because the product was designed and sized to address a specific application type. Most PCs and some embedded products do allow RAM memory to be upgraded. Additional memory on a PC will increase its performance by reducing the number of hard drive accesses required to run a program. Additional memory on an embedded product may help increase the number of applications it supports. Scalability There is a large investment in learning specific software applications like HMI, PLC programming, and database architectures. Scalable software products reduce the level of investment, since one common programming or operational environment can be used for the smallest embedded device up to the largest PC based system. Microsoft Windows operating systems provide scalability, as they offer similar graphical interfaces from Windows CE up to Windows NT / Microsoft also supports this level of scalability with its classic PC applications. Word and Excel applications are available in Windows CE and desktop Windows versions. Unfortunately, at the time of this writing, the Windows CE versions are only licensed for CE-based Handheld PCs (HPCs). Some industrial software vendors are working on similar scalability for their core products. Future Growth In addition to selecting operating systems and software products to solve today s industrial application, many users are thinking ahead to possible future expansions of the target system. For example, in two years it may be desired to connect an embedded HMI device to the factory network, to allow operators electronic access to company information. Or maybe a staged installation calls for a stand-alone PC today, with plans to network it in the future with other factory floor PCs. Both desktop and embedded operating systems allow for future growth, within the constraints of the hardware platform and the availability of future applications to solve the task. Embedded applications may not be as common as desktop applications, so planning is required to ensure that applications will be available. Page Rockwell International

13 Summary Today s Windows-based computing devices use both desktop and embedded operating systems. Each operating system is designed to provide a unique set of features and functionally for its target task. Desktop operating systems provide a very powerful set of features for desktop PCs. The trade-off is the need for high power CPUs, large hard drives, and cooling fans for the PC enclosures. These mechanical devices are weak links for the PC hardware durability in typical factory floor application environments (high temperature, shock, and vibration). Embedded operating systems provide a more targeted solution for each application, allowing a more focused hardware implementation, typically with a 100% solid state design. The trade-off is embedded devices are not as powerful or flexible as desktop PCs, and can t run the wide variety of applications currently available for PC operating systems. When designing a Windows-based industrial computing application, it is important to understand the differences between embedded and desktop operating systems. The user needs to consider the application with respect to connectivity, performance, scalability, and any future growth plans. An embedded device will typically provide a more durable, focused solution to a specific application, while a PC-based device will provide a less durable but more powerful standard and easily expandable solution Rockwell International Page 13

14 Appendix A. Choosing the Right Windows Operating System for Industrial Computing Applications Attribute Rating Scale 1 1 = Poor, 2 = Fair, 3 = Good, 4 = Very Good, 5 = Excellent Operating System Attribute Desktop Operating Systems Embedded Operating Systems Windows Windows Embedded Windows CE 95/98 NT/2000 Windows NT Total System Flexibility (ease of adding hardware and software to the computer) 2 Reliability Network Connectivity Security features of the O/S Plug & Play Capability (NT) / 5 (2000) 1 1 Multimedia support Breadth of available software Ease of adding new application software to previously installed hardware platforms Ease of hardware system migration & expandability Application software portability ability to run on multiple CPU types Application software portability difficulty of porting as related to operating system software standards Ease of application software modifications 1 Ease of operating system installation (NT) / 5 (2000) N/A N/A Compactness of software installation Hard real-time determinism (Ver. 3.0) Degree of understanding the operating system capabilities and applications among RA customers Scalability These are only relative ratings provided to guide the user toward the effective use of a Windows Operating System based on the user s specific industrial computing application requirements. These ratings do not endorse one operating system use over another. 2 Embedded NT supports the full Win32 API, so it has more potential for expansion, portability, and flexibility. However, an Embedded NT development kit is required to change a system configuration. 3 No Plug & Play in Windows CE 4 Embedded NT and Windows CE are installed by the manufacturer, not by an end user. Publication 6000-WP002A-EN-P 2000 Rockwell International

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16 Publication 6000-WP002A-EN-P 2000 Rockwell International