Alan Freedman -- The Computer Language Company - Computer Desktop Encyclopedia
Computer Desktop Encyclopedia
Longest-Running Tech Reference on the Planet

A CDE Definition

You'll love The Computer Desktop Encyclopedia (CDE) for Tech Term of the Day (TTOD)

LOOK UP ANOTHER TERM


PAC

(1) See perceptual audio coding.

(2) (Programmable Automation Controller) A programmable microprocessor-based device that is used for discrete manufacturing, process control and remote monitoring applications. Designed for use in rugged, industrial environments, PACs combine the functions of a programmable logic controller (PLC) with the greater flexibility of a PC. They are also more easily set up for data collection and integration with the company's business applications than PLCs.

Although each PAC vendor uses its own development environment (IDE) and programming language, PAC networking is typically based on IP and Ethernet. Taking advantage of off-the-shelf microprocessors, PACs were developed in the 1990s to provide a single industrial controller that would provide the functions of a DCS and PLC. The term was coined in 2001 by the ARC Advisory Group (www.arcweb.com). Contrast with PLC and DCS.




PACs in Operation
The large white boxes are Opto 22 SNAP PACs in Chevron's Richmond, Virginia research facility. Processing the PID loops, the wires come from thermocouples that sense pipe temperature in a laboratory test that analyzes the best way to break down crude oil. The PACs determine when to raise and lower temperatures, and the three modules with the black sockets send digital signals to the heaters (cables not connected in this image). (Image courtesy of Opto 22, www.opto22.com)






Personal Use Only

Before/After Your Search Term
BeforeAfter
P6PACBASE
P6 classPacifica
P7pack
P75package
P90package manager
PApackage on package
PA-RISCpackaged software
PA systemPackard Bell
PaaSPackard Bell NEC
PABXpackbase

Terms By Topic
Click any of the following categories for a list of fundamental terms.
Computer Words You Gotta KnowSystem design
Job categoriesUnix/Linux
Interesting stuffPersonal computers
InternetIndustrial Automation/Process Control
Communications & networkingAssociations/Standards organizations
HistoryDesktop publishing
Audio/VideoGraphics
MainframesSecurity
ProgrammingHealthcare IT
System design