The Fast Merging Module (FMM) for readout status processing in CMS DAQ

The Fast Merging Module (FMM) is part of the Trigger Throttling System (TTS). The TTS adapts the trigger frequency to the DAQ capacity in order to avoid congestions and overflows. The states of all data sources (~640 in the case of CMS) are read out and merged by the FMM to obtain the status of each detector partition. The functionality and the design of the FMM are presented in this paper.