PLCs are definitely changing. At the low end, in the sub-$1,000 price range, nano and micro-PLCs are gaining capability and offering lots of bang for the buck. At the high end, PLCs are becoming more like PCs every day. Sales are soaring and PLCs are here to stay.
Even market analysts, who predicted for years that industrial PCs would eventually replace PLCs, have given up on that story line. "That dog won't hunt," was the universal response to the analysts' PC takeover theories.
"Omron does not feel PCs will ever replace PLCs," says Jon Giardina, PLC market manager at Omron Electronics (www.omron.com). "PLCs are also now applied in applications where they couldn't be applied before. The barriers in cost and programming are disappearing. In addition, PLCs offer platform stability and long-term availability that PCs don't offer."
Rockwell Automation agrees. "So far, PC-based soft control' has not addressed the end user's overriding need for reliability, durability, and ease-of-use," says Mike Miclot, marketing manager at Rockwell (www.ra.rockwell.com). "These are three attributes that PLCs offer in abundance."
You can see some of those new capabilities in the first of this two-part roundup of PLC products that follow.
Duplex PLC Goes Redundant
Omron Electronics
800/556-6766
www.info.omron.com
VME-Based PLC
GE Fanuc
800/648-2001
www.gefanuc.com
Linux-Based Controller
Sixnet Circle
518/877-5173
www.sixnetio.com.
Logic Module Replaces Switches
Siemens Energy & Automation
800/964-4114
www.sea.siemens.com
Flow Computer for PLC
The MVI71-AFC flow computer for Allen-Bradley's PLC platform measures hydrocarbon gases and liquids using AGA 3, 7, 8, and GPA 15 and 25 measurement standards, and API 2540 calculation standards. The module uses process data collected by PLC analog I/O modules to calculate flow rates, accumulated volumes, and accumulated mass. The results of the calculations are transferred back to the processor for use in the application ladder logic, or for transfer to a SCADA host.
ProSoft Technology
661/716-5100
www.prosoft-technology.com
Controller Gets Connected
Rockwell Automation
800/223-5354
www.ra.rockwell.com
Industrial PC Fits In
Rugged TECLA programmable data processors have USB, Ethernet, PS/2, serial and embedded I/O, and allow Allen-Bradley I/O to be directly plugged into the unit. Options include extra serial ports, PCMCIA/Cardbus, and DeviceNet. The PC has a Microsoft Windows CE.NET v. 4.2 operating system. Disk-on-chip storage eliminates shock, vibration, and grit problems, and the PC does not need a fan.
Online Development
865/579-4740
www.oldi.com.
Look for the second installment of "PLCs Change Names and Application the week of November 24.)