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

HVAC Control in the New Millenniumers are also Web enabled. They allow user-supplied Web pages andapplets to be downloaded to the terminal server and accessed fromthere. These applets can communicate with the terminal server and thento the equipment over the Ethernet connection, for monitoring, controland other functions.One use for these applets is to allow tasks such as configuration,troubleshooting, and maintenance. The manufacturer provides theseresident applets. To configure the system, you point a Web browser atthe Web server in the equipment or terminal server and configure thesystem from the pages shown. Troubleshooting can be provided as listsof alarms or fault indications with suggested corrective actions.The maintenance and troubleshooting can even be handled remotelyover the Internet. The use of the remote user-interface can provideinformation on all aspects of the machine or equipment. The hardwareinterface provides monitoring of the system and could also controlthe equipment. Capabilities well beyond the scope of the original controllercan be incorporated simply.There are many PLCs that now include some capability for embeddingWeb pages and applets within the controller itself or within anothermodule on the controller such as an Ethernet communicationsmodule. Future advances in PLCs will enable support for real-time,server-side Java.This would allow the PLC to provide monitoring and real-timecontrol. Web-based interfaces and integration could be provided directlyfrom the PLC, which would program such logic in Java on both theclient and the server.Using the technologies of the Internet on a local Intranet can providea cost-effective method of improving integration (Table 9-3). Manynew controllers may include embedded Web pages for troubleshootingand maintenance.Merging Information and ControlIn today’s deregulated environment, improving plant and facilitycompetitiveness is a driving force behind most HVAC control systemreplacements. New control systems not only control plant operations,but also improve the access to diagnostic information that can helpimprove efficiency, reliability and cost effectiveness. This is a change©2001 by The Fairmont Press, Inc. All rights reserved.