PCs Are Gaining Control

Benefits of using PC technology for machine and process control have been extolled for some time. Vendors have responded with many new products—both hardware and software. Even though sales of PC-based control products for manufacturing have not grown rapidly, there are many success stories showing what the technology can deliver.

By Gary A. Mintchell, CONTROL ENGINEERING February 1, 1999


Machine control

Software for control

PC-based control

Microsoft Windows

Sidebars: PCs help power Honda line

Benefits of using PC technology for machine and process control have been extolled for some time. Vendors have responded with many new products—both hardware and software. Even though sales of PC-based control products for manufacturing have not grown rapidly, there are many success stories showing what the technology can deliver.

Bill Thompson, senior analyst at Automation Research Corp. (ARC, Dedham, Mass.), authored the latest study of the “SoftLogic” market. He notes, “The SoftLogic market did not realize the growth rates that previous ARC studies predicted, primarily because of the maturity of products in the arena and uncertainties about the choice of Microsoft Windows NT as the primary platform. While the message is clear that users want NT, the real-time extension battles distracted users from focusing on control applications. The introduction of Windows CE has further complicated the issue.”

Mr. Thompson also sees users wanting to use Microsoft technologies like NT, COM, DCOM, and OPC. This enables OEMs and end-users to leverage a broad pool of programming talent already familiar with these technologies and integrate more readily with the Information Technologies department. This view is reinforced by many new installations and the explosion of new products.

Initial debate revolved around the separate issues of real-time and determinism. Real-time refers to whether the control system can update the I/O data table and process the control program in the time required by the process. Some processes, like motion control, require times in measured in microseconds, while others are real-time with updates in the 5- to 10-min. range. Determinism refers to whether the operating system allows the highest priority tasks to work without interruption from those with lower priority. A measure of determinism is the amount of time from the time of an interrupt service request of the processor until the request is serviced.

Deterministic behavior

Marcus Schmidt, Microsoft Corp. (Redmond, Wash.) industry marketing manager, points out that Windows NT was not designed as a real-time, manufacturing control operating system. While the features of NT are often the right tool for control, Microsoft’s strategy for real-time, deterministic control is Windows CE. The current version, 2.0, has a determinism time of about 500 microseconds and lacks COM. The goal for version 3.0 is a determinism time of 50 to 100 microseconds with a minimum of jitter. COM will be included in this version as will the number of real-time threads to assure stability of control. Windows CE 3.0 will be in beta in the first half of 1999 with release following in the last half of the year.

Meanwhile, there are many examples of successful PC installations. Nickolas Kayes, Intellution (Norwood, Mass.) marketing programs manager of Soft Logic says, “Customers are successfully using SoftLogic control in high-speed applications such as packaging and material handling, where improved performance means improved output and higher productivity. They can combine HMI, control and motion functions into one box eliminating hardware and lowering system integration costs.” For example, Motts Apple Juice, with the assistance of Engineered Products & Systems Inc., needed to improve bottle fill accuracy without sacrificing line speed. A Fix Paradym-31 soft logic system with Fix DMACS human-machine interface running on a PC solved the problem.

John Bergsten, vice president of software, Controls Division, Total Control Products (Edmonton, Alberta, Canada ) says control engineers find PC control offers advantages of improved flexibility, connectivity, and information access. Even more, hardware is available from a wide array of suppliers, so it can be easily and inexpensively expanded and upgraded. PCs are less costly to configure for networking, interface with complex devices, and mix I/O device brands. Among the applications for Total Control Products’ FrameworX software are machine tool transfer line control, transmission machining and assembly control, control for CO 2 laser used in cutting, grooving and welding, operational control for pipelines, packaging equipment control, and Control for drawing and cutting fiber-optic cable.

Jim Fall, president of MDSI (Ann Arbor, Mich.), says users don’t care whether or not the solution is “open.” What they want is a solution that works. Before introducing its PC-based OpenCNC on Windows NT to the market, the beta machines ran six months, three shifts per day six days per week without a failure. Tecumseh Products is installing OpenCNC in applications previously controlled by PLCs as well as in CNC applications. PC-based control is driving down life-cycle costs and allowing integration with other software like computer-aided manufacturing.

Engineers who have grown up with PCs are asking for PC-based solutions according to GE Fanuc Automation (Charlottesville, Va.) senior vice president, Vince Tullo. High-speed machining, a tank farm in the textile industry, and a tire forming machine are applications running GE Fanuc’s PC Control. Why was PC control picked? The ability to work with different types of I/O devices, integration with HMI, and ease of troubleshooting are most often cited by users.

“The best applications for us have been where a great deal of flexibility was required,” says Randall Thompson, director of marketing at PC Soft International (Mansfield, Mass.). “Users needed the communication and processing power of PCs to do things that would have been more difficult in a PLC. Windows CE is going to be the platform that sets PC-based control on fire. Users will finally be able to get something that seems like familiar controllers, but with all the benefits of an open platform. Look for our products to move onto CE very quickly. This will allow us to offer common tools from the embedded control level up to the supervisory level.”

According to Scott Kiser, Wonderware InControl product manager (Irvine, Calif.), “Currently we are seeing customers develop applications like integrating control, ActiveX objects, multiple I/O interfaces, motion, vision, and HMI with PC-based control that are not possible with PLC’s. There are companies doing oil well head control, conveyor control, pick and place insertion machines, food manufacturing, and automotive manufacturing applications. The coming of a more deterministic Windows CE will continue to drive costs down while increasing performance.”

Integrate data and HMI

Bob Muniza, business manager, Open Controls, Rockwell Automation (Mayfield Heights, O.) states, “Like any new control or other option, certain applications and markets are accepting PC-based control faster than others. We see automotive and material handling applications leading the market. A recent study on PC-based control indicates chemicals may soon be a leading application area. This is mainly because of the ability of PC-based control to handle high levels of information. Early adopters want to integrate control and information. The most common reasons for moving to PC-based control include a need for more memory capacity, lower initial acquisition costs, and the desire to integrate control with data and with human machine interface software.”

Gary Marchuck, sales and marketing manager for Think & Do Software (Ann Arbor, Mich.) notes three main reasons users have adopted PC-based control are integrated control—logic, motion control, PID, and/or serial communications, data handling, and integration to business information system for scheduling or reporting. Applications employing Think & Do software logic and sequencing of a semiconductor packaging machine including eight axes of motion and eight PID loops, a high speed sortation and distribution conveyor system, and a batch and food processing application.

Matthew Mikula, product manager, control and software tools, Cutler-Hammer/Eaton (Westerville, O.), says OEM customers cite development cost savings, low cost networking, and remote diagnostics as benefits of installing PC-based control. End users like productivity improvements, easy networking, and data handling capabilities.

Tom Muth, marketing manager software technology, Omron Electronics (Schaumburg, Ill.), says customers have asked for PC-based control, yet still want assurance about deterministic performance. While waiting for the market to settle on an operating system for control such as Windows CE 3.0, Omron has introduced a hybrid—a PLC on a PC board. This allows the benefits of both worlds.

There is a non-Windows alternative. SoftPLC (Humble, Tex.) uses an embedded real-time operating system (RTOS) and Java for programming. Marketing vice president, Cindy Hollenbeck, says customers get cost savings, flexibility and choice with PC-based control. SoftPLC’s users are found in the automotive, food, power, metals, paper, and wood products industries. She continues, “We also see movement toward such other operating systems as Linux. Customers understand that applications are what solve problems, not operating systems.”

Another alternative to Microsoft Windows for control comes from CTC Parker (Milford, O.). General manager, Jay Vierling, says, ‘NT appeals to manufacturers because of its enterprise-wide acceptance, openness and robust networking topologies. Although our development software runs on NT, there are some inherent obstacles such as a machine-level PLC alternative. An effective NT configuration will typically cost 5 to 10 times more than the cost of a PLC. Our DOS-based product is competitive with small PLCs. Although MachineLogic has just been introduced, several machines demonstrated at the last Pack Expo used it for control of packaging equipment.”

According to Steeplechase Software (Ann Arbor, Mich.) PC-based control is best used in applications of >50 I/O points and multiple tasks, such as programming, HMI, and SCADA, which can be performed on one PC with a common database. It cites automotive, material handling, packaging, and semiconductor applications.

George Meares, VMIC (Huntsville, Ala.) vice president of research and development, sees a recent movement from “window shoppers” to people with real interest and funded projects. “Adopters want a single development environment that can be used throughout their enterprise. This means a product that single product that is both applicable and cost-effective for high speed continuous processes as well as low speed batch processes.”

From data acquisition to control

National Instruments (Austin, Tex.), well-known supplier of test and instrumentation products, has a real-time version of LabView for control applications called LabView RT that works with a new series of intelligent data acquisition (DAQ) boards. Typical automation applications include machine control, process control, as well as engine simulation, control, and test.

Labtech (Wilmington, Mass.) is another company that has moved from test and measurement into control. President Fred Putnam says, “Our approach to PC-based control has been to focus initially on the lab, then to scale to pilot production, and finally to full scale manufacturing. Acceptance in the early ’80s was low. Gains in reliability and speed of PC hardware, improved software, and greater user experience have contributed to growing acceptance.

Mark Knebusch, Phoenix Contact (Harrisburg, Pa.) Interbus group director, points to successful automotive component manufacturing transfer lines as the beginning of acceptance for PC-based control. He continues, “The ability to provide accurate and intuitive information to operators is a plus from using NT.”

Siemens (Alpharetta, Ga., Nürnberg, Germany) entered the PC-based control market in 1998 with WinAC, an NT-based product, and MP270 based upon CE.

Benson Hougland, Opto 22 (Temecula, Calif.) director, technical marketing, says that engineers adopting PC-based control are not just replacing PLCs, but are solving problems not even thought of before. Looking for ways to provide choices for users, Opto 22 now offers some products based on Linux, a Unix-like operating system.

Dennis Brandl, Sequencia (Phoenix, Ariz.) director of enterprise initiative, notes that initial cost considerations and increasing computing power are moving its customers into PC-based control.

PCs are in control

There is no doubt that many companies are trying PC-based control. Early indications are that most installations have met objectives. Are PCs the future of control? It sure looks like it now.

PC Control Vendors


Source: Control Engineering. Because software is a rapidly changing and expanding area, please check with vendors to verify the strategies used with the latest release of various software offerings. For free information, visit www.controleng.com/info .

Windows NT

Advant OCS
Windows NT, RTX

Adept Technology
NT, 95

Aerotech Inc.
U500, U600
95, NT


Soft logic/DCS, solution PCP Virgo



Aspen Technology

Alspa P3200 for utilities

Ci Technologies

CJ International

Comdale Technologies
Expert systems

Control Systems International
Field Control System

CTC Parker


HMI & PLC for process control

Elsag Bailey
Symphony, Freelance 2000



GE Fanuc
PC Control


Smart Control

Honeywell IAC
Total Plant Solution


Imagination Systems
Real-time system

Integrated Systems Inc.
Psos, psos +
Real-time system, tools

FIX Paradym-31

Intrinsyc Software
Integration Expert Windows NT,
CE Development Tools

Intuitive Technology
Web@aGlance server

Klopper & Wiege
NT with real-time kernel

Labtech Control,
Control Pro
DOS, Windows 3.1, 95


Open CNC

Mitsubishi Electric Automation

Moore Automation
APACS Process Control System

National Instruments
Bridgeview, Labview RT
NT, NT with PC board

OpenControl, Paragon
NT/Hyperkernal, NT

PERC Virtual Machine

Object Automation
OAenterprise 98

OMNX Direct Control

PLC on PC board

Opto 22
OptoRuntimePC, Factory Floor

PI System

PC Soft

PEP Modular Computers
Smart2 PLC

Real-time ETS kernel for NT
Real-time systems, tools

Phoenix Contact
Remote Field Controller
Rtos, CE (in beta)

QNX Software Systems
Real-time systems

Real-time systems

Rockwell Automation
Allen-Bradley Automation

Rockwell Software

Schneider Automation
TSX Premium
PLC on PC board


WinAC, MP270

4 Control

Embedded RTOS/Java

Visual Logic Controller

TA Engineering

Think & Do
Think & Do

Total Control Products

Real-time systems

IOWorks NT/VxWorks

Westinghouse PCD
Web Access View Enabler (WAVE)

Wind River Systems
Real-time systems

Factory Suite 2000, InControl

Yokogawa Industrial Automation
Centum CS 1000

PCs help power Honda line

Honda of America Mfg., Anna Engine Plant (Anna, O.) has begun using PC-based control on modular transfer machines. While the vast majority of lines are controlled by programmable logic controllers, Honda chose PC-based control for these machines because of ease-of-use, information integration, ability to handle multiple I/O devices and communication options. The site recently upgraded three modular transfer machines with Allen-Bradley SoftLogix 5 controllers.

Built in 1985, Anna Engine Plant, Honda’s largest, contains aluminum and iron casting, machining, and assembly operations producing 900,000 engines per year. The plant manufactures engines for cars including the Acura, Accord, Civic, and Odyssey, Gold Wing and Valkyrie motorcycles, and various suspension components. The upgraded machines are on the V6 cylinder head line responsible for milling, drilling, tapping, boring, and reaming.

“We needed to upgrade because the existing control technology was more than 10 years old,” explains Nick Balster, engineering coordinator at Honda Engineering North America. “We managed individual programmable controllers on as many as 14 different machining stations and loading and unloading stations. A lack of spare parts made the system difficult to maintain, and an outdated relay interlocking system made troubleshooting time consuming.”

Honda and local Allen-Bradley distributor F.D. Lawrence (Sidney, O.) engineered and installed three SoftLogix 5 systems. The systems handle control and sequencing for all stations on each machine. One system replaced fourteen programmable controllers on one line. Two systems replaced 23 programmable controllers on the linked second and third lines.

“The new system is really about passing information from station to station via software rather than hardware,” says Mr. Balster. “Using Rockwell RSView32 HMI software, we can access line management data and control such information as abnormal file alarms, output, and tooling data. The data is collected into Microsoft Excel for analysis.”

Reliability tests relieve skepticism

A series of reliability tests to criteria similar to programmable controllers was implemented to know and understand expected behavior at start-up, during processing, and at shutdown. These were off-line simulations that were successfully completed before Honda made the final decision to proceed with PCs.

The Honda team recommends those considering PC-based control evaluate many systems, compare possible system benefits, and understand how the system or machine will fit into the entire plant’s system before purchasing. Honda teamed both the company’s engineering group and the manufacturing group to assure that each group’s requirements were met by the new system.

PC-based control has delivered time and cost savings for Honda. Since installation more than a year ago, the three control systems have been running without problems or a crash. In fact, the team is satisfied enough to have just installed a fourth system.