TAGnet a twisted-pair protocol for event-coherent DMA transfers in trigger farms
S Gonzalve, A. Guirao-Elias, H. Müller, F. Bal, Vinci Dos Santos, F · CERN Document Server (European Organization for Nuclear Research) · 2002
This E.C.D. approach has the following advantages over conventional eventbuilding approaches as far as they applicable at these rates: TAGnet is a link protocol developed for high-rate hardware eventbuilding in trigger farms.Its first implementation is in the level-1 VELO trigger system of LHCb where all data sources (Readout Units) need to receive destination addresses for their DMA engines at a trigger rate of nominally 1 MHz.TAGnet organises event-coherency for the source-destination transfers and provides the proper timing for best utilization of the network bandwidth.The serial TAGnet LVDS link interconnect all Readout Units in a twisted-pair ring, which is controlled by a TAGnet scheduler.