the LHC Compact Muon Solenoid experiment detector control system

The Compact Muon Solenoid (CMS) experiment at CERN is a multi-purpose experiment designed to exploit the physics of proton-proton collisions at the Large Hadron Collider collision energy (14TeV at centre of mass) over the full range of expected luminosities (up to 1034cm-2s-1). CMS detector control system (DCS) responsibility is to ensure a safe, correct and efficient operation of the detector so that high quality physics data can be recorded. The system is also required to make possible that inexperienced shifters can operate the detector and a small crew of experts can take care of the maintenance of its software and hardware infrastructure. The DCS large subsystems size sum up to more than a million parameters that need to be supervised. A cluster of roughly 100 servers is used to provide the required processing resources. A scalable approach has been chosen factorizing the DCS system as much as possible. CMS DCS has made clear division between its computing resources and functionality by creating a computing framework allowing for plugging in functional components. DCS components are developed by the subsystems expert groups while the computing infrastructure is developed centrally. To ensure the correct operation of the detector DCS coordinates the communication between the accelerator and the experiment systems making sure that the detector is in a safe state during hazardous situations and it is fully operational when stable conditions are present. This paper describes the current status of CMS DCS focusing on operational aspects and the role of DCS in this communication.