ICs instead of PLCs?
Grika points out that an industrial computer offers an advantage over traditional controllers. "In contrast to more traditional controllers such as PLCs, ICs integrate the latest in powerful processors to accomplish more control with less hardware. Advances such as the Intel Core 2 Duo make it possible to bring more centralized control architectures to more applications. The old saying goes that you should never do in hardware what you can do in software and, as PC processor technology marches on, there is exponential growth in the percentage of industrial functions that can be carried out in software running on an IC."
The examples below—an adaptive control system and a handheld HMI—illustrate the powerful process available in an IC.
Since you can change out an IC in a matter of hours, one interesting tactic is to invest in high-quality industrial displays. Rick Tomfohrde, manager of HMI business development at Pepperl+Fuchs, says a "split architecture" approach is worth considering: "Regardless of consumer versus industrial grade computers, the processor engine technology is not particularly costly—less than $500 in some cases—meaning that total replacement is often a trivial maintenance expense."
The same cannot be said of the operator display. These can get expensive—$1,000 or more for a high-quality, large-screen, ruggedized monitor that can survive industrial environments. "Keeping the display/touchscreen independent of the PC processor box allows the more costly piece of the architecture to outlast many changes of the less costly piece," Tomfohrde advises.
Maybe you don't want to upgrade that industrial computer at all. As Berryman points out, "Once the line or process is designed and built, industrial control applications often do not change for years. New capabilities for graphics, services and networking are simply unnecessary. In fact, many control applications could run very well on older x86 processors for decades."
PAC, Panel PC or Portable IC?
It's safe to say that most industrial computers are cut from the same PC-based hardware and software cloth. The point is, industrial computers (in whatever form) offer you a reliable, rugged and relatively inexpensive platform on which to perform control, test, measurement and data acquisition functions. Let's look at some examples.
Semicore Equipment manufactures vacuum coating and etching systems. Matthew Hughes, president of Semicore, says his company abandoned PLCs in favor of PC-based control seven years ago and recently switched to Beckhoff industrial computers and TwinCAT software. The first application of the new Semicore control system was implemented on one of the most complex machines the company ever built. "It was really a trial by fire for the Beckhoff controls because the application was as demanding as it gets in our industry," Hughes said. "The project was to develop a brand new coating system that applied diamond-like carbon, chromium carbide and titanium nitride coating on internal surfaces."
Figure 2. Emerson's DeltaV Mobile Worker uses a Panasonic Toughbook portable computer so operators can walk around the plant with a fully functional DeltaV operator station in their hands.
The project went well. "The new machines equipped with Beckhoff controls have been well-received and helped increase reorder rates," says Hughes.
Impact Drilling's Secure Drilling System uses a PAC and LabVIEW software from National Instruments to track the complete pressure profile of a well during the drilling process while dynamically adapting to well conditions to meet desired drilling parameters. With high-speed monitoring and advanced adaptive control technologies, the Secure Drilling system can automatically control the back pressure at the surface to maintain well control.
"This single HMI and logic development environment of LabVIEW makes deployment of the control system simple because the HMI is built in the same environment as the control system," says Jason Hannam, controls engineer at Impact Drilling.
Emerson Process Management put a complete DeltaV operator station on a Panasonic Toughbook U1 handheld computer, rated as a Class 1 Division 2 device. The DeltaV Mobile Worker (Figure 2) permits operators to carry a fully-functioning, connected operator interface with them into the plant. Wi-Fi or cellular communications connect the handheld to the DeltaV control network via a DeltaV RAS Server and VPN firewall.
When a major DCS vendor uses an industrial computer for control, PC and Windows technology have arrived in the process control world.
Rich Merritt is a Control contributing editor.
Windows in the Plant
Many industrial computers use Windows XP, XP Embedded, or Windows CE—operating systems that are relatively solid. Windows CE is often used in embedded diskless systems, such as Panel PCs and PACs, and some HMI/SCADA software (not all!) will run on CE. HMI/SCADA software from almost every vendor will run in Windows XP systems, however. When you consider that some of the biggest vendors in process control use Windows CE and XP in their controllers, it is safe to assume that it must be reliable.
However, if you are really worried, just ask the industrial computer vendor what operating system is being used, and pick one that does not use Windows. One recent product—the Power PMAC motion computer from Delta Tau (http://www.deltatau.com/common/index.asp?connectionStr=release) —uses) — usesa PowerPC processor with a Linux operating system, so non-Microsoft industrial computer products certainly exist.