E787 data acquisition software architecture

Brookhaven National Laboratory (BNL) Experiment 787´s second generation Unix-based data acquisition system is comprised of several independent programs, each of which controls a specific aspect of the experiment. These programs include packages for reading events from the hardware systems, analyzing and reducing the data, distributing the results to various data consumers, and logging the data to tape or disk. Most of these can be run in stand-alone mode, for ease of development and testing. There are also a number of daemon processes for writing special data records to the data streams, and several monitor programs for evaluating and controlling the progress of the whole. Coordination of these processes is achieved through a combination of pipes, signals, shared memory, and FIFOs, overseen by the user through a Motif graphical user interface. The system runs on a Silicon Graphics 4D/320, interfaced to a Fastbus system through the BNL Fastbus/VME interface (BBFC), and runs under Irix and Motif/X-windows