Accelerator Magnet Control from an SMP Workstation

Steve Herb, H.G. Wu
Deutsches Elektronen Synchrotron (DESY)


Standard commercial workstations and operating systems now support real time scheduling on multiprocessor machines, which opens new possibilities for structuring of control systems. We have built a prototype accelerator magnet control system based on a Sparc 10 workstation with two processors running the Solaris 2.4 operating system, which permits soft real time scheduling in a symmetric multiprocessing environment. Fieldbus I/O is handled by a real time task which monopolizes one processor and communicates via queues with VME fieldbus drivers, leaving the other Sparc CPU free to handle a mix of real time and time sharing tasks, including higher level controls functions and network communications. Intertask communications use API level commands which access queues and data structures built in shared memory with C++. Tests indicate that the throughput is adequate for controlling the more than 1000 magnet power supplies of the HERA electron and proton storage rings.