The central trigger control system of the CMS experiment at CERN

The Level-1 (L1) Trigger of the CMS experiment uses custom-made, fast electronics, while the experimentʹs high-level trigger is implemented in computer farms. The Central Trigger Control System described in this poster receives physics triggers from the Global Trigger Logic unit, collects information from the various subdetector systems to check if they are ready to accept triggers, reduces excessive trigger rates according to preset rules and finally distributes the trigger (“Level-1 Accept”) together with timing signals to the subdetectors over the so-called “Trigger, and Timing and Control” (TTC) network of the experiment. The complete functionality of the Central Trigger Control System is implemented in one 9U-VME module and several ancillary boards for input and output functions. The system has been used successfully during CMS test runs with cosmics and beam.