Product Roundup: PLCs Becoming PACS as MRC Invents New TLA

By Rich Merritt, Senior Technical Editor

Market Research Companies (MRCs) Have Given Up Predicting the Demise of Programmable Logic Controllers (PLCs)

OR YEARS, MRCs HAD A STRANGE, ILLOGICAL FASCINATION with PC-based controls, and annually predicted the coming demise of PLCs. PCs will drive PLCs out of the market, the MRCs would say. All this was much to the amusement of machine builders, process equipment skid builders, end users and system integrators, who were buying PLCs as fast as they could. If PCs were being used for automation and machine controls, it was mostly for HMIs and certain motion control tasks.

PC-based controls barely put a dent in the huge PLC market, and everybody seemed to know it except the market analysts.

Finally, one of the chief proponents of PC-correctness, ARC Advisory Group (www.arcweb.com), appears to have given up. As is its wont, it created another three-letter acronym (TLA) called Programmable Automation Controller (PAC), said PLCs are now PACs, and it is now happy to predict that the sales of PLCs … er, PACs … will remain as strong as they always have, at about 4.6% annual growth, reaching $7.5 billion by 2008.

As for industrial computers, Venture Development (www.vdc-corp.com), predicts that they will continue to grow at 4.4% annually, reaching $537 million in the industrial automation, control and instrumentation marketby 2006.

In other words, there is nothing new in the machine control marketing research universe except another TLA.

The whole purpose of coining new TLAs, it seems, is to sell market research reports at $6,000 a pop. Although PLC vendors and machine builders already know as much about the PLC market as do MRCs, they buy the study just in case there is some new information they might have missed.

Some commodity pico and nano-PLCs now cost less than relays, commodity micro PLCs have the capability of the full-size PLCs of 10 years ago, and larger PLCs have become hybrid controllers with PC architectures, networking and web servers. You can buy commodity PLCs in the $100 range, especially with OEM quantity discounts. And if you pay $1,000 for a PLC, you get an outrageously powerful device. Going the other way, you can get a PLC on a chip and embed it in your machine.

No matter what you call them, PLCs are still the most reliable devices on the planet. That, plus their low cost, is why machine builders cling to them with such tenacity.

As you can see in the product round-up that follows, PLC vendors are keeping their products extremely competitive and up-to-date by using the latest hardware, software, and communications technology. This month’s Round-Up has PLCs and PACs with web servers, fieldbus networks, Linux operating systems, motion control functions and firewalls.

Although some may consider PLCs to be 40-year-old devices, they are as up to date as Kansas City. And, as we all know, “Everything’s up to date in Kansas City” (from the musical, Oklahoma!, which was revived last year on Broadway, with PLCs moving the scenery).

Brick-Style PLC Gets Off Its AS-iz

Enhancements to the MicroSmart brick-style PLC series include an AS-interface (AS-i) master module and an eight-point 120-VAC input module. The AS-i allows the PLC to communicate with slave devices such as sensors, actuators, and remote I/Os, using signals transmitted over the AS-i bus. The 120-VAC input module allows a user to apply 120 VAC directly into the PLC input card. This eliminates additional signal conditioning devices. Programming is via WindLDR version 4.5 software.
IDEC: 800/262-IDEC; www.idec.com

Pico PLC Performs Simple Control Functions
The Pico GFX-70 performs simple logic, timing, counting and real-time clock operations. It has an HMI, processor/power supply, and I/O modules. The LCD HMI can show text, date, time, custom messages and graphics, and allows operators to acknowledge fault messages, enter values and initiate actions. The integrated graphic display lets engineers program control and HMI functions with one software package, or with on-display buttons.
Rockwell Automation: 800/223-5354, ext. 1675; www.ra.rockwell.com

PLC Performs Motion Control
The 317T PLC uses Step 7 software, so only one program is needed for PLC and motion control on up to 16 axes. Motion control functions include positioning in absolute, relative, additive and superimposed operating modes, geared synchronous motion, electronic cam disc and cam, moving to a positive stop. It also has a measuring probe for print-mark correction.
Siemens Energy & Automation: 770/751-2477; www.sea.siemens.com

PLC Software Runs Linux
Version 4 of SoftPLC control is built on an embedded, real-time version of Linux. Enhancements include integrated firewall support, encrypted secure communications with the FTP Server, and remote command shell access to run programs, perform diagnostics, and restart the controller. Remote file access lets the software read/write production data to a remote disk.