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

PC-based Control, Software and Bus Trendsstand-alone machines or fully automated process networks.Another approach combines Windows NT with real-time extensions.VMIC has IOWorks which is a PC-based control software developmentpackage for these real-time extensions.Windows NT can also be used with a real-time operating systemlike VXWorks. In the case of VxWorks, two computers are involved; oneis used for Windows NT development and HMI and a VxWorks computerhandles the real-time application. This provides an acceptable PCbaseddevelopment environment with the security and performance ofa proven real-time operating system like VxWorks.CSI has a User Configurable Open System (UCOS) that was designedto run QNX on PC-based hardware. The QNX OS is mature andreliable and easy to integrate with Windows NT-based engineering andoperator workstations.UNIXBefore Windows, UNIX was one of the dominant operating systems.In this era of open systems, some vendors such as ABB, CSI,Foxboro, GE Fanuc, Honeywell, MDT, USDATA and others still offerUNIX products. GE Fanuc’s CIMPLICITY is based on VMS and UNIX.CIMPLICITY was rewritten for the Windows NT platform and releasedin 1995.UNIX retains a considerable legacy base. But, while UNIX systemscan provide a role in database support, UNIX systems lack the availableintegration technologies such as those found in Microsoft products.Some software vendors that do not directly support UNIX applicationssee the need to communicate with them. The newer methods forconnectivity are mostly in the form of Microsoft provided connectivityfor databases on non-Microsoft platforms. These are typically UNIXbaseddatabases.LinuxLinux has been growing as it moves into more and more applications.Many of these are through the back door as an inexpensive, highperformance,unbreakable server platform, which is also capable of©2001 by The Fairmont Press, Inc. All rights reserved.