The CMS data acquisition architecture

The architecture of the detector readout and data-handling systems planned for the Compact Muon Solenoid (CMS) experiment at the LHC is reviewed. The systems are expected to operate with events of average size 1 MByte at a level-1 trigger rate of 100 kHz. A network-based readout architecture is described and the problems to be solved are highlighted. These include specialized data acquisition and event filtering units and advanced data communication techniques (buses, links and switches) for readout and event building. Solutions are presented which exploit the future industrial developments which are expected in telecommunications and computing technology.