used to be, you’d buy a human-machine interface (
HMI) just to get an operator interface (OI); that is, a device that lets you look into the process to see what was going on, and adjust or control what you saw. Such plain-vanilla OIs are certainly still available, but the overall roles of HMIs are changing.
Today, HMIs are taking over control, data acquisition, web access, maintenance, diagnostics and enterprise functions. The OI function remains, of course, but telling an operator what is going on seems to be the least of an HMI’s many tasks.
Virtually all desktop and panel HMIs are now based on a PC architecture and run some version of Windows. A certain number of handheld and PDA-based HMIs are also appearing and, while all are not Windows-based, the ones we see are compatible with the Windows architecture.
The “big iron” HMIs can be extremely powerful PCs, capable of running just about any kind of control, data acquisition, and SCADA software package. Many HMIs serve as the gateway between a process control system and its process historian, ERP, supply chain, and other higher-level software packages. That is, they gather the data from plant floor equipment, put it into XML or some other common database format, and ship it off to the enterprise software in a timely fashion. Some HMIs are powerful enough to host enterprise software.
HMIs can also be extremely tiny, embedded, diskless processors that can operate inside equipment and instrumentation. When equipped with an embedded Windows operating system, such as Windows CE, the embedded systems provide many of the functions of the big iron systems.
HMIs big and small also serve as the gateway to the Web for many process control systems. The HMI hosts the necessary web servers that allow remote PCs or HMIs to access Web pages via the Internet. Web access lets an instrument engineer be paged at home, receive an e-mail that says there is a problem at the plant, find out what is going on via a home PC’s web browser, and make the necessary setpoint changes at 3:00 a.m., all without having to run into the plant.
Venture Development (www.vdc-corp.com
) says that browser-based terminals are gaining in popularity for several reasons, not the least of which is reduced operating costs. Many HMI vendors have a “per-seat” charge, where you pay thousands of dollars for the original HMI/SCADA software, and then pay for every additional terminal or “seat” onto which the software is loaded. With a browser-based system, you still pay thousands of dollars for the original software, but you can eliminate per-seat charges by using browsers to view the display screens.
Over on the accounting side of your business, the IT folks are probably looking into “hosted” software, such as CRM or CAD. In this case, the CRM software runs on the vendor’s server somewhere, the IT people gain access to it from a browser, and they pay only for what they use. Such capability will be coming to process control one of these days, but we see no evidence of it yet. We suspect that HMIs will be the first to use a hosted system, because HMI software vendors are always way out in front of everybody else in the control business.
The new breed of HMI/SCADA systems are selling fast. ARC Research (www.arcweb.com
) says the HMI software market will reach $559 million by 2008, an annual rate of 5%. That’s faster than the overall automation market. “HMI and related software has become a critical component in the infrastructure for successfully managing manufacturing operations,” says ARC’s research director, Craig Resnick.
In the roundup that follows, we have examples of HMIs performing all of the above-noted functions. This roundup also kicks off a new capability here at CONTROL magazine: the marriage of print and web. If the writeup indicates that more product details are available at ControlGlobal.com, we mean it.
For example, we provide additional product information on our site. Just like the brief product writeups, we take additional information from the vendor, edit out all the product manager’s superfluous comments and the vendor’s unsupported claims, and provide you just with additional facts.
Also, instead of just giving you the vendor’s web site address, we provide links to the vendor’s product literature whenever possible. This means you will be able to click directly to the product’s data sheet or brochure without having to hunt it down on the vendor web site or fill out those tedious qualification forms.
Let us know if this works for you, and tell us what else we can do to improve future product writeups.