With facilities around the globe, Woodward Industrial Controls (Rockford, Ill.) is a leading provider of control systems, components and related services for large industrial prime movers, such as steam turbines, gas turbines and reciprocating engines.
Woodward produces comprehensive microprocessor-based systems that automatically control critical speed, load, pressure, temperature and environmental emissions, as well as operations and maintenance data.
The controls are based on high- powered programmable logic controls specifically designed for prime movers. The specialized inputs and outputs, as well as the graphical programming environment, are tailored to the unique needs of the company's markets. The system is flexible, allowing Woodward engineers to define any control laws and sequential logic necessary for each application and run it on the controls.
In the past, Woodward built its own CPU modules for scheduling and task switching that ran a proprietary, scaled-down version of Unix called Xinu. But the company wanted to stop making the CPU modules.
The problem was that Woodward's circuit-board-manufacturing and -stuffing capabilities could not compete price-wise with high-volume manufacturers. Pentium-based CPUs were available from several vendors that were a lot more economical.
The first product to use the new platform was the existing MicroNet control. It is a VME-based system consisting of one or more VME chassis with a variety of I/O modules. The original MicroNet CPU design used Woodward's proprietary Xinu architecture for several years with great market acceptance. However, new feature requirements and the complexity of controlling low-emission gas turbines forced a new CPU strategy for the MicroNet control.
After deciding to use a Pentium-based CPU, the Woodward team needed to choose an operating system. It evaluated several choices, including the Wind River, QNX and Microsoft Windows NT Embedded operating systems, and chose the latter primarily for its built-in connectivity features.
Specifically, The COM and TCP/IP all came with the operating system. Previously, Woodward engineers had to write those utilities themselves.
However, if a customer needed some other kind of networking protocol, it was possible to add that to the footprint, resulting in a variety of available state-of-the-art functionality.
The open development environment was another plus, allowing the company to write its own applications and do debugging on desktop PCs running Windows NT workstations.
Another reason for choosing Windows NT Embedded was that the team could keep the entire software footprint-applications and OS-under the 72 Mbytes that was available on the module's disk on chip.
One requirement for the applications that Woodward produces is deterministic real-time response-the ability of the system to make a decision or respond to an event in real-time. The team evaluated a couple of products to work in tandem with Windows NT Embedded before choosing VenturCom's Real Time Extensions (RTX) for Windows NT.
VenturCom's RTX adds real-time scheduling to Windows NT, shortening the determinism time resolution from the 5-millisecond-or-more range to 30 microseconds. That ensures predictable, reliable behavior in systems with time-critical response and enhances the ability of Windows NT Embedded to do high-speed data acquisition, motion control and plant equipment automation applications. All the generic capabilities of Windows NT are retained, including the ability to run third-party applications.
Woodward engineers took the skeleton of the scheduler from the old system and remapped it onto Windows NT Embedded with RTX to provide the same functionality as a base from which to grow.
To mesh the two capabilities, developers divided the application into two sections-a Win32 side and a real-time side. Anything that is required to update in a fixed time is on the real-time side, which includes updates that must run within 5 ms.
Examples of real-time operations include adjusting the fuel/air ratios and controlling every aspect of engine operation. Everything else that's nondeterministic is all on the Win32 side. Information that is gathered from the real-time part of the application is made available to other applications on the Win32 side, such as trending, monitoring, maintenance and operator applications.
In creating the Windows NT Embedded-based version of the MicroNet control, developers were able to port over much of the functionality of the old Xinu operating system.
Once the porting was complete, Woodward software engineers created a working footprint of the operating system in about three weeks so that they could start testing. Then they used the Target Designer tool to create a Windows NT Embedded run-time operating system that met their size requirements.
It took the Woodward team about three months to fine-tune the system down to the 36 Mbytes area and to create some component definition files.
The MicroNet control also employs sophisticated concepts, such as the component object model, distributed component object model and remote procedure calls functionality, which are natively supplied in Windows NT Embedded.
Woodward is in the process of developing a second version of the product that, similar to the MicroNet control, uses a Pentium CPU board. Instead of the VME format, this product, Atlas, is based on PC/104. Atlas has fewer inputs and outputs and is designed for smaller prime mover applications. It is a little bigger than an A-4 size sheet of paper and also can be expanded to six modules, increasing it from about 3 inches tall to 6 or 7 inches.
Because Woodward wanted Atlas to be compatible with the MicroNet control, it used all the software that was being developed for the MicroNet project and simply added a different Ethernet driver and modified the way it talks through the bus to the board. Because Atlas uses compact flash memory on the Pentium CPU, it also required the minimal installation of Windows NT Embedded.
Using the Target Designer, developers were able to create a working footprint of the operating system for Atlas in about a day. Then they spent a month and a half fine-tuning it.
The Atlas product takes advantage of the null video, keyboard and mouse drivers in Windows NT Embedded to create a headless system, without a monitor, keyboard or mouse.
Porting the MicroNet control to the Windows NT platform enables Woodward to react quickly to a customer's needs. It opens up an avenue for adding major functionality like communications. A customer might want to synchronize all units with a real-time clock card that grabs a signal from a satellite, for example.
In another example, a customer asked for a Profibus implementation on one of its controls that enables devices from different manufacturers to communicate without a special or custom interface. In the past, that meant developing a board that would go onto the bus and having development engineers write all the drivers. With Windows NT Embedded, the Profibus card and the drivers that run on Windows NT were all that was needed.
An obvious advantage is that Windows NT Embedded can shorten time-to-market and reduce costs.
Woodward can buy PC boards from large-volume producers much more cost-effectively than it can build the few hundred it needs each year.
The flexibility of Windows NT Embedded has opened the door to even more inventive capabilities as time goes on. One idea Woodward is considering for future implementations is to enable each unit to be a Web server that makes Web pages available to maintenance personnel, showing the diagnostic status of the system. That could make it possible to service units over the Web from a centralized location.
Health monitoring and predictive maintenance are key issues with many turbine and engine manufacturers.
The system could monitor critical parameters and send e-mail to plant maintenance people, signaling them to maintain a certain system or warning them when a part is about to fail.
In building its MicroNet and Atlas industrial controls on Windows NT Embedded, Woodward achieved its ultimate business goals, which were to shorten time-to-market, increase functionality and lessen dependence on its own manufacturing capabilities for PC boards.