Author: Kotturi, K.D.
Paper Title Page
TUCAUST04 Changing Horses Mid-stream: Upgrading the LCLS Control System During Production Operations 574
  • S. L. Hoobler, R.P. Chestnut, S. Chevtsov, T.M. Himel, K.D. Kotturi, K. Luchini, J.J. Olsen, S. Peng, J. Rock, R.C. Sass, T. Straumann, R. Traller, G.R. White, S. Zelazny, J. Zhou
    SLAC, Menlo Park, California, USA
  The control system for the Linac Coherent Light Source (LCLS) began as a combination of new and legacy systems. When the LCLS began operating, the bulk of the facility was newly constructed, including a new control system using the Experimental Physics and Industrial Control System (EPICS) framework. The Linear Accelerator (LINAC) portion of the LCLS was repurposed for use by the LCLS and was controlled by the legacy system, which was built nearly 30 years ago. This system uses CAMAC, distributed 80386 microprocessors, and a central Alpha 6600 computer running the VMS operating system. This legacy control system has been successfully upgraded to EPICS during LCLS production operations while maintaining the 95% uptime required by the LCLS users. The successful transition was made possible by thorough testing in sections of the LINAC which were not in use by the LCLS. Additionally, a system was implemented to switch control of a LINAC section between new and legacy control systems in a few minutes. Using this rapid switching, testing could be performed during maintenance periods and accelerator development days. If any problems were encountered after a section had been switched to the new control system, it could be quickly switched back.  
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