Increasing options for designers and users of control systems are driving almost every supplier of control system components. This concept is seen in such areas as controllers, networking, I/O modules and devices, and now in hardware for human-machine interface (HMI). Cathode-ray tube (CRT) monitors borrowed from the computer industry followed little electroluminescent alphanumeric displays as the hardware base for providing information to operators. Continual innovation in PC technology is also driving new products in industrial control.

Connecting an interface to a controller once required hardware and software from the controller vendor or the slow RS-232 serial protocol. With PC prices falling and Ethernet connections proliferating, it is easy to use PCs as HMI hardware. The growing popularity of Microsoft Windows CE for embedded (read "diskless") computers provides even more growth opportunity for the PC platform. Most people are now familiar with Windows graphical user interface (gui). Designers using icons on their gui (pronounced "gooey") find touchscreens are an ideal input medium. The sidebar, "Information at a touch," discusses the variety of touchscreen technologies to help users choose the correct one for their application.

Rick Tomfohrde, Christensen Displays (Preston, Wa.) vice president, says that PCs and flat-panel displays for industrial HMI are "following the volume" for price and performance. "Standard open platform LCD monitors will be based on the volume notebook PC-sized, 12- to 15-in. panels. Smaller solutions will be based on high-volume car navigation systems, while 18- to 20-in. LCD monitors are based on the high performance desktop and financial/medical markets. Today, a fully equipped PC with industrial LCD monitor and HMI software costs no more than a proprietary graphics panel with its associated peripherals."

Flat-panel displays have many benefits for an industrial HMI designer. Jim Thorp, operator interface product line manager at Cutler-Hammer/Eaton (Westerville, O.), states, "Flat panel display technology is advancing rapidly. Flat panels have better reliability than CRTs and are catching up in such important areas as resolution, clarity, and viewing angle. They also weigh less, take up less space, generate less heat, and are virtually immune to display and color distortion caused by magnetic interference found in many industrial environments." Mr Thorp adds, "Advantages to OEMs and end-users are longer life, flexible mounting and location options, and lower life cycle costs."

Mike Tschantz, Nematron (Ann Arbor, Mich.) hardware product manager, notes, "Our customers have expressed no interest in CRT-based products for new projects, so we have no plans to design new products on that technology. Flat-panel designs benefit from more viewing area per size and lower power required. Backlight lifetimes have increased significantly further reducing maintenance costs."

An analysis by Xycom Automation (Saline, Mich.) points to a growing acceptance of PCs on the factory floor. The continued pace of increasing power and functionality of commercial PCs, combined with stable to downward prices, means industrial PC vendors will actually be able to provide more power than a typical HMI solution needs for less cost. This "excess" computing power can and will be used for other functions, including control. The boundaries between HMI and other functions like control and enterprise computing will continue to blur.

Bob Steinberg, president of Iicon (Morgan Hill, Calif.), notes, "There is a trend toward larger screen and liquid crystal display in combination with touchscreens. Even though the price of LCD is decreasing, CRTs are still less expensive. An OEM building machines at a lower price point will be sensitive to that price differential. However, designers want to put more information on screens to accommodate increasing complexity. This requires larger screens. The application environment will then dictate touchscreen type.

Microsoft Windows CE is an operating system with substantial implications for hardware design. (See May 1999 CE, p. 54 for discussion of its use as a control platform.)

Mike Sims, product manager, Rockwell Automation Industrial Computer Business Unit (Duluth, Ga.), says, "Windows CE enables the use of lower-cost hardware platform. Applications similar to today's PC-based HMI programs can be run on lower cost RISC-based (reduced instruction set computting) embedded computers. With its small footprint, applications can run out of a few megabytes of solid-state memory instead of hundreds of megabytes of hard disk space. CE is easier to maintain than Windows NT and allows designs to draw less power and run cooler. The end-user benefit is lower cost, smaller size, and easier maintenance."

Another benefit evolving from new technology is greater resolution in LCD displays. Greater resolution enables more detailed graphics required by today's software; 12.1-in. flat panel LCD displays from Rockwell now have 800 x 600 pixel resolution while a new 18-in. color LCD has 1,280 x 1,024 pixel resolution.

"Windows CE will be the real game-breaker," says Rob Brooks, GE Fanuc Automation (Charlottesville, Va.) industrial computer business unit manager. "It will not only drive down prices making PC-based control more competitive, but it will also open many new control and monitoring market opportunities for industrial suppliers and OEMs. Imagine a building wired to find hot zones connected to a PC. A fire fighter en route to the fire pulls out a pocket-sized Windows CE computer with built-in wireless communications, connects to the building computer, and learns where the trouble spots are before arriving."

Siemens Energy & Automation (Alpharetta, Ga.) positions Windows CE devices between operator panels and PLCs on one hand and PCs on the other. These "multi-functional platforms" combine dedicated hardware robustness with the PC's flexibility. They are just as viable for control as HMI applications.

Mr. Brooks also sees bundled software/hardware packages providing value for users. They can be assured that the application will boot up and work on the supplied hardware without requiring the usual set-up and debug time.

Paul Ruland, Automationdirect.com (Cumming, Ga.) product manager, notes, "A pre-integrated HMI product adopted from the consumer PC market eliminates compatibility problems, saving the user time and effort." He also sees growing use of Windows CE products as they lower cost and improve connectivity.

Omron Electronics (Schaumburg, Ill.) also sees bundling applications as a value to users. In its case, Omron bundles a PLC programming editor in its HMI terminal. Connectivity is also becoming quite valuable to HMI system designers and users capitalizing on the flexibility inherent in open systems. As HMI products incorporate open operating systems, bus and network types, processors, and communications protocols, users will have the freedom to choose equipment from multiple vendors to tailor systems to fit their application. Users should expect to see more functions at lower prices with smaller form factors over the next few years.

Increased flexibility is a customer demand, according to statements from an Exor (Wellington, Fla.) representative. Manufacturers are responding to this demand by offering a range of products from dedicated text displays, through larger dedicated color graphic terminals, to industrial computers. Windows CE will have a major impact on HMI hardware in the next few years, offering solutions from embedded board-level products to diskless workstations, all with network capability.

Windows CE will allow for a significant size, cost, and footprint reduction in control and HMI products say representatives from Mitsubishi Electric Automation (Vernon Hills, Ill.). These reductions should generate greater sales volumes, which in turn will generate some additional cost savings. This new hardware base will make possible the integration of control and HMI on a single platform. These drivers will bring benefits of high-end computing to the low-end market.

What if the application is in a hazardous area? A small but significant area of new product development lies in harsh duty and hazardous area applications. Computer Dynamics (Greenville, S.C.) sees a growing market for flat-panel displays especially designed for installation within Class I, Division 2 areas. This development brings graphic interface to process plant operators and maintenance personnel out in the plant environment.

Azonix (Billerica, Mass.) is among others designing products for Class I, Div. 1 or Div. 2 areas.

Variety and flexibility are the dominant trends in HMI hardware, reflecting the controls industry in general. LCD interfaces are getting bigger, sharper, and less expensive. New operating systems like Windows CE are aiding the smaller, less expensive trends. And just when you think that there are no options for that tough application, along come special products for harsh duty and/or hazardous areas. Manufacturers are providing the choices. Choose wisely.