S-LINK, A DATA LINK INTERFACE SPECIFICATION FOR THE LHC ERA

In the Technical Proposals for the ATLAS, CMS and ALICE experiments at CERN, there is a requirement for several thousand data links. Althoug h there is an obvious need for standardisation, this seems difficult t o achieve as the links run at different speeds, over different distanc es and have various constraints of power consumption, size and radiati on hardness. An additional complication is that today we cannot decide which will be the most cost effective technology for the implementati on of the final links. Furthermore, we must allow designers of boards at each end of the link, for example read-out electronics and input bu ffers, to work in parallel with the development of the links. The S-LI NK is a new concept which should provide the benefits of standardisati on without these limitations. The S-LINK specification defines, at bot h ends of the link, a simple FIFO-like user interface which remains in dependent of the technology used to implement the physical link. The p hysical link provides transfer of event data and control words, error detection, optional flow control and test facilities. This paper descr ibes the S-LINK specification and gives examples of the use of the S-L INK, the physical links being designed, and the test equipment that is being developed.