Engineering Manual o.. - HVAC.Amickracing

BUILDING MANAGEMENT SYSTEM FUNDAMENTALSINTEGRATION OF OTHER SYSTEMSGENERALInformation from other subsystems, such as fire alarm,security, access control, or lighting control, may be requiredin the BMS. This can be achieved through system integration.There are two ways to integrate these systems: surfaceintegration and in-depth integration. These subsystems arenot described here but are mentioned because of theirimportance in the BMS architecture.SURFACE INTEGRATIONA surface integrated subsystem is a stand-alone system whichprovides certain point information to the BMS. See Figure 10.The subsystem transmits alarm and status information throughmultiple point connections hardwired to a local BMS panel.The BMS processes and displays that data as auxiliaryinformation or uses it as inputs to resident programs such astime/event sequences. Every input desired in the BMS requiresa separately wired point from the subsystem. Since thesesubsystems are stand-alone systems, they have an operatorinterface which can be monitored separately from the BMSmonitor. There are cases where a second window in the BMSterminal display is dedicated to the operation of the connectedsubsystem. This usually requires only a standard link to theBMS terminal. In this case, the terminal is shared but noinformation is passed to the BMS for use in operations.Additionally, the display for the subsystem will generally beentirely different in format from the display for the rest of theBMS. Consequently, this type of integration is of limited use.BUILDING MANAGEMENTSYSTEMFIRE ALARMSYSTEMThe advantage of surface integration is that limitedsubsystem information is made available to the BMS. Thistype of integration is generally used to tie in existing systems toeliminate the need to replace functioning equipment.The disadvantages of surface integration are:— Higher first cost because of duplicated equipment andincreased installation to connect the two systems— Interconnection between systems is not supervised andcould fail without notifying the central— Independent operations staffs may be required formonitoring each subsystemIN-DEPTH INTEGRATIONFigure 11 shows a system with in-depth integration. Systemlevelcontrollers communicate over a common bus for eachsubsystem. These processors are designed to operate as standalonesystems if the communication link with the operationslevelprocessor fails. The system-level controllers for fire andsecurity subsystems can also provide outputs for localannunciation if required by applicable codes. All data isaccessible through all PC stations, however all operators neednot be authorized to access all data. All of the subsystems aretied together through software. Information can also be passedto additional buses containing other subsystems such aslighting control for true global control. This communicationis essential for some operations such as smoke control. Evenwhen multiple buses are used, a common display format andcentralized collection and dissemination of informationthroughout the system provides for a more reliable, smootheroperating system.OPERATIONS-LEVELPROCESSORSYSTEM-LEVELPROCESSORCRTTERMINALPRINTERPROCESSORBMSPANELOPERATORINTERFACESENSORSANDACTUATORSRecently, open standard communications protocols have beeninvented and adopted by the building control and related controlindustries. Theses standards, such as BACnet and LonMark,will make in-depth integration of products and systems frommultiple vendors, and from multiple industries, much easierresulting in lower cost and more functional integrations.BMSPANELFIREALARMPANELHARDWIRED CONNECTIONSC1868Fig. 10. Surface Integrated System.196ENGINEERING MANUAL OF AUTOMATIC CONTROL