THE DAQ SYSTEM FOR CLEO-III

In 1998 the CLEO detector collecting data at the CESR storage ring wil l be upgraded. A new Data Acquisition system will be installed during the upgrade to record triggers up to 1000 Hz with a mean data size of 25 KBytes per event. In this largely improved system, we will exploit the new CBLT VME transfer mode (defined by VIPA) to readout crates wit h about 15 9U digitization cards. Secondly, we decided to design and b uild a FASTBUS-VME interface card with the dimension of a FASTBUS card , and a 2-slot VME backplane inside. With this interface, all hardware and software will be homogeneous at this point of the DAQ data pipeli ne. It will also perform additional sparsification and channel tagging ''on the fly''. This new system will be monitored and controlled by a networked system of CPUs. To achieve a dynamical and simple connectio n method between the various processes we chose the CORBA standard com munication method. The port to PowerPC based VME boards was done in cl ose collaboration with Visigenic Corp. (C) 1998 Elsevier Science B.V.