Choose your operating system

To remain competitive in the global marketplace, manufacturers need the right information to be in the right place at the right time. Rockwell Automation's Paul Herron looks at how using right operating system can make a big difference

Many of today's dedicated operator interface terminals use proprietary operating systems and development tools which have nothing in common with Supervisory PC-based HMI and information systems. This can lead to duplication of effort and long project development times. Bridging the gap between machine- and supervisory-level applications across a complete architecture of products results in greater productivity and a lower total cost of ownership.

It is important to select the right HMI operating system (see Figure 1), and Microsoft offers both desktop computer and embedded operating systems based on common technologies and standards. Each is broadly targeted at specific areas of computing, and Microsoft Windows operating systems inherently provide scalability as they offer similar graphical interfaces from Windows CE up to Windows NT or Windows 2000. All these operating systems follow a consistent networking strategy which makes it easy to get them working together. They can also be reliably connected to major fieldbus systems.

The application requirements for any manufacturing enterprise HMI need to be determined along with networking, performance, and future enhancement needs. It is then easier to decide whether the application is better suited to either an embedded or desktop PC operating system.

At the HMI level, Windows CE based computers offer an alternative to dedicated or proprietary operator interface products. They can provide functionality similar to that 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.

The Windows CE Embedded operating system is a targeted solution, giving a more focused hardware implementation, typically with a 100% solid-state design. The trade-off is that 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.

Supervisory control At the supervisory level, a desktop operating system may be required for large operator interface applications, particularly those with complex data collection requirements. Desktop operating systems provide powerful features but the disadvantage is that they need high power CPUs, large hard drives, and cooling fans for the PC enclosures. These mechanical devices are weak links for PC hardware durability in harsh factory floor environments where they may be subjected to high temperature, shock and vibration.

CE based computers can still play a role even in larger HMI applications. If configured minimally as thin clients they can be inexpensively deployed to provide multiple windows into an application from across a site. Information management applications are typically based on desktop operating systems, because they support superior data management, networking, and large storage devices. There is also an abundance of information-related software applications available for desktop PCs. Windows CE based computers do not have the resources needed for these applications but they can have a role as auxiliary devices when configured as thin clients.

Network connectivity is an important consideration for industrial applications. This includes both communication with factory floor control devices (PLCs, barcode scanners and sensors), as well as net-working back to a higher level computer or information system. Both desktop and embedded Microsoft operating systems support a variety of Ethernet-based network protocols with internal drivers.

Embedded products may use integrated interfaces to support factory networks, or have PCI, PCMCIA, or PC104 expansion board interfaces. For each network card required it is simply necessary to make sure that the necessary drivers are available. Factory floor control networks, like DeviceNet, ControlNet or Profibus, require special interface cards which traditionally plug into a PC backplane, with vendor-specific drivers for desktop operating systems.

Unified products Rockwell Automation set out to introduce a common development environment for HMI applications that allows runtime projects to be used at all levels. This meant choosing operating systems that support common features and development tools across dedicated and open PC-based devices, and it has been achieved using Microsoft operating systems. Rockwell calls its family of unified software and hardware visualisation products ViewAnyWare.

ViewAnyWare's common development environment is delivered using RSView Studio - a Win-dows2000 design environment for both the machine-level and supervisory-level products. The result is a scalable and unified suite of monitoring and control solutions for virtually anywhere in the manufacturing enterprise. Simplifying the way applications are developed makes them easier to develop and implement, and leads to better productivity with lower overall lower costs. A common development environment eliminates the need to be familiar with two development packages (one for machine level operator interfaces and one for supervisory HMIs), which speeds up development and implementation times. Operator interfaces can more closely match applications and offer integration with better performance. They will also provide backward compatibility as well as forward-friendly features which can be exploited through the variety of networks used by the application.

Incorporating the full range of Allen-Bradley hardware platforms means that open system platforms, such as the Allen-Bradley RAC6000 range of industrial computers and future dedicated operator terminals in the PanelView family, will take full advantage of the benefits and scalability of the RSView Enterprise Series.

The Rockwell Automation Information Platforms business is currently developing a complete family of next-generation PanelView products that will form an essential part of the ViewAnyWare architecture. These optimised embedded products will be configured from the RSView Studio common development environment and will support application reuse, portability, and interoperability across the full range of ViewAnyWare-compatible products.

Sensible deployment of Microsoft technologies has allowed Rockwell Automation to bridge the gap between traditional, dedicated machine-level HMI devices and distributed, supervisory-level PC-based HMI systems, with ViewAnyWare bringing together Rockwell's strength in dedicated operator interfaces, open industrial computing platforms, and PC-based HMI software. INOC

 

Fig 1: Choosing the 'right' Windows operating system for industrial computing applications
Operating System Attribute	Desktop Operating Systems		Embedded Operating Systems
	Windows95/98	WindowsNT/2000	Embedded Windows NT	Windows CE
Total system flexibility (ease of adding hardware and software to the computer (2)	4	4	3	2
Reliability	2	3	4	5
Network connectivity	2	4	4	2
Security features of the operating system	1	3	4	5
Plug and play capability (3)	5	2(NT) / 5(2000)	1	1
Multimedia support	5	5	3	2
Breadth of available software	5	5	4	2
Ease of adding new application software previously installed hardware platforms	5	4	2	1
Ease of hardware system migration and expandability	4	5	2	1
Application software portability - ability to run on multiple CPU types	1	2	3	5
Application software portability - difficulty of porting as related to operating system software standards	4	5	3	2
Ease of application software modifications (1)	4	4	3	2
Ease of operating system installation (4)	4	3(NT) / 5 (2000)	N/A	N/A
'Compactness' of software installation	1	1	4	5
Hard real-time determinism	1	1	3	4 (v3.0)
Degree of understanding the operating system capabilities and applications among RA customers	4	3	1	1
Scalability	2	5	1	5

In the attribute rating scale used above, 1=poor, 2=fair, 3=good, 4=very good and 5=excellent.

'Operating System Attributes' references:
1. These are only relative ratings provided to guide the user toward the effective use of a Windows OS based on the application requirements. These ratings do not endorse one OS over another
2. Embedded NT supports the full Win32 API, so it has more potential for expansion, portability and flexibility. An Embedded NT development kit is required to change a system configuration.
3. No plug and play in WinCE
4. Embedded NT and Windows CE are installed by the manufacturer, not the user

• Rockwell Automation
  Email b102@industrialnetworking.co.uk