HVAC Control in the New Millennium.pdf - HVAC.Amickracing

HVAC Control in the New MillenniumWindows NT/2000 ChangesWindows NT Version 4 is being released as Windows 2000. It hasadded support for DirectX, which is Microsoft’s multimedia platform,changed its driver architecture to be compatible with Windows 98 plugand-play,and made a number of other changes. With the introduction ofWindows 2000, Microsoft has made some strict rules regarding what cango in the SYSTEM directory of Windows NT.For system users, these changes have been largely a plus, addingcapability and compatibility. Most beta testing indicates little or no difficultiesin migrating from Windows NT 4 to Windows 2000. Preliminarytesting of existing applications in Windows 2000 Professional and Windows2000 Server has resulted in only minor setup problems.Several companies such as Intellution, Wonderware and SoftPLChave developed programs that run on a PC that emulate a PLC. Theseprograms use ladder logic and allow the PC to function like a PLC.There is a development platform and a run-time platform, and insome cases an operator interface front end. Most programs such asParadym-31 from Intellution have a self-documenting capability and cango from ladder logic to other programming techniques.Software SuitesThe trend in control automation is towards tightly integrated softwaresuites. The access of diagnostic information is a major part of thecontrol management and configuration software. OPC enabled automationsuites may include the supervision, operator interface, reports, diagnostics,calibration and maintenance. The configuration package mayinclude the construction of control strategies and simulation.OPC is bringing major changes in the way diagnostics are managed.Fieldbus devices provide a driver for OPC, just as printers use adriver for Windows.Companies that previously only dealt with software may now sellit preinstalled in a PC, with interfaces as a console product. Users thenplug in the field devices without the setup problems of cards, driversand interrupt conflicts.Users can ensure that they get devices with the diagnostics theyneed to reduce control variability and downtime. Fieldbus devices are©2001 by The Fairmont Press, Inc. All rights reserved.