PLCs and Industrial PCs merging identities

These days, you can’t tell the players without a program — or with one. Senior Tech Editor Rich Merritt provides a Product Roundup of PLCs and Industrial Computers.

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By Rich Merritt, Senior Technical Editor

MARKET predictions for PLCs and industrial computers say that sales will continue to increase at about 5% per year in the face of worldwide economic slowdowns. ARC Advisory Group reports the worldwide market for PLCs will grow at 5.9% and the China market for PLCs will grow 14.1%. Venture Development Corp. says the growth rate for ruggedized industrial computer systems is 4.4%. IMS Research pegs the world growth of PLCs at 3.3% and growth in the Asia-Pacific region at 6-7%. Disagreeing market researchers aren’t unusual. In fact, since their purpose is to sell $3,500 reports, it helps their sales to disagree loudly and publicly.

Alas, none of these researchers directly addressed the use of PCs and PLCs in process control, so we’ll just have to wing it. Based on what we’ve observed, and as indicated by the products you’ll see in the roundup below, some of the apparent trends are:


  1. Logical controllers: PLC-like logic is beginning to be embedded into otherwise normal PID controllers, temperature controllers and similar devices. Motor drives are beginning to either embed PLCs, or the drive manufacturers are abandoning their proprietary systems in favor of off-the-shelf PLCs. Paper machine builders also appear to have abandoned their proprietary control systems in favor of PLCs.
  2. Mixed-up controllers: It’s getting very difficult to tell the difference between some PLCs and some industrial computers. PLCs have process control-like functions, such as PID control, historians and built-in web servers. Some of the computers are impossible to define because, although they are based on a PC chip architecture, they employ PLC-like IEC 61131 languages and support many common industrial and PLC networks, such as Profibus, Modbus, Ethernet IP, DeviceNet and so on. Is it a PC or a PLC? The only way you can really tell anymore is if the vendor calls its device a PLC or an industrial computer. We may simply have to start calling this category “Industrial Controls.”
  3. Open controllers: Proprietary systems continue to dwindle. More and more PLCs and industrial PCs have open WinTel (Windows-Intel) architectures, support all device and network interfaces, and come with software that allows the device to communicate up and down the enterprise with ease.

These trends and limited print space make it very difficult to describe some of these complex devices. If you see “more info at” in the device description below, it means we have more information about the product on our web site. Go to, scroll down to “Site Highlights,” and click on the roundup section. Then, select the PLC/PC roundup from the list of product roundups you’ll find there.


Product Roundup:
PLCs and Industrial Computers

Touchy Computer
Optima Touch industrial computer has an integral LCD touchscreen monitor, comes standard with the Windows XP operating system, and can be configured with several HMI software packages. It is available with a 15 or 10.4-in. TFT flat-panel LCD and a continuous analog resistive touchscreen. The computer has a 1.3-GHz Celeron CPU, 512 MB RAM, and a S3 ProSavage4 4xAGP 3D/2D video controller. More info at Eurotherm; 703-669-1329;

Speedy PLC Historian
In-rack PC56-Historian provides high-speed, real-time data collection, stores and accesses data locally in a module for ControlLogix controllers, and communicates with the ControlLogix controller directly via the ControlBus backplane. It can be added to new or existing ControlLogix PLCs without changing the control application. More info at ProSoft Technology; 661/716-5100;
Many Ports in a Storm
4115T flat-panel industrial computer has a 2.0-GHz Intel Pentium 4 processor with 533-MHz system bus and 512-KB cache, 15-in. flat panel LCD, and an analog resistive touchscreen. Its 4xAGP graphics controller has up to 64-MB video RAM for handling 3-D graphics. The PC has on-board 10/100 Base-T Ethernet, two USB 2.0 ports, parallel port, two RS-232 serial ports, one configurable RS-422/232/485 serial port, PS/2 keyboard and mouse ports, and an additional video port. More info at Xycom Automation; 734/429-4971 ext. 471;

Multi-loopy Controller
PPC-2000 multi-loop PID controller has built-in programmable logic functions, allowing various analog and digital I/O plus control loops to be centralized into one compact unit and programmed as an integrated system. It handles up to 48 PID loops with 80 analog inputs and 46 digital I/O available for logic programming or monitoring. Inputs include thermocouples, RTDs, linear dc voltage or current inputs and counters. Watlow; 314/878-4600;

16 Analog I/O on Two Boards
Elite-2000 offers up to 16 analog inputs and outputs built onto two boards. Each analog expansion board incorporates its own processor, and can be manufactured for up to eight analog inputs and eight analog outputs in various configurations. The analog cards are factory configured to accommodate a customer's specific requirements with no wasted I/O. More info at Entertron Industries; 716/772-7216;

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