Status and Prospects of the data acquisition systems of the Large Hadron Collider experiments

Data Acquisition systems are an integral part of an LHC experiment. They are designed to meet the needs set by the physics programme. Despite some very interesting differences in the architecture, the unprecedented data-rates expected at the LHC have led to a lot of commonalities among the four large LHC data acquisition systems. All of them rely on commercial local area network technology and more specifically mostly on Gigabit Ethernet. They transport the data from the detector readout-boards to large farms of industry standard servers, where a pure software trigger is run. These four systems will be reviewed, the underlying commonalities will be high-lighted and interesting architectural differences will be discussed. In view of a possible LHC upgrade we will briefly discuss the suitability and evolution of the current architectures to fit the needs of SLHC.