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

HVAC Control in the New Millenniumwork become mandatory to ensure reliable data delivery.The HVAC control system is required to generate closed-loopcontrol and deal with network demands. One solution is to add asecond processor dedicated to the network interface. This interfacemust be defined carefully to avoid limiting the data flow through thesystem. Limited data flow means the control is compromised.Traditional controllers are light on performance. While this mayhave worked fine for simple designs, the network interface-connectivitychanges everything. Good logical computational engines for thefinite state machines used in most network protocols and numericcapability are needed for closed-loop control calculations.Reconfigurable ComputersNew techniques are emerging from the study of reconfigurablecomputing which was originally proposed in the late 1960s at UCLA.Reconfigurable computing had been delayed by a lack ofreconfigurable hardware. Reprogrammable logic chips like field programmablegate arrays (FPGAs) have been available for years, butthese chips have only recently reached gate densities that make themsuitable for more complex applications. FPGAs now have severalhundred thousand reprogrammable logic gates with an anticipateddoubling of gate densities every 18 months.TSI TelSys are using reconfigurable computing technologies inground-station equipment for satellite communications. This applicationinvolves high-rate communications, signal processing, and a varietyof network protocols and data formats.The hardware has a great deal of functional flexibility since thelogic in the FPGA can be changed when necessary. This allows hardwarebug fixes and upgrades to be administered as freely as software.In order to support a new version of a network protocol, youredesign the internal logic of the FPGA. Reconfigurable computingalso allows manipulation of the logic in the FPGA at run-time. TheFPGA acts as an execution engine for the different hardware functions.Some are executing in parallel and others in serial fashion. TheFPGA functions as a reconfigurable processing unit (RPU).Reconfigurable computing allows the system to execute morehardware than there are gates for. This works when there are parts of©2001 by The Fairmont Press, Inc. All rights reserved.