This stage is required only if there is more than one Data Input Module.

The data received from each data input module is passed between the data input stage and the data merge stage via shared VME memory. All data items are identified by an associated global timestamp. The data merge stage takes all these data input streams and creates a single merged time-ordered data stream. This task will be performed within a single PowerPC VME processor module. The data stream generated will be formatted into data blocks using the same common internal representation as is used for the input data.

The data blocks are then passed to the data selection stage of the Event Building system. It will also be possible to send directly to the Tape Server thus permitting the raw data to be written to tape.

For the GREAT system the Data Merge Stage will be a component of the Data Collector VME crate.

Back to Event Builder main page