Control System Reliability for the KEK Linac

Norihiko Kamikubota, Kazuro Furukawa, Kazuo Nakahara,
Isamu Abe and Akihiro Shirakawa

National Laboratory for High Energy Physics (KEK)

New control system for the KEK 2.5-GeV electron/positron linac, which comprises seven VME stations with the OS-9 operating system and Unix-based workstations, has started operation since October 1993. During the 11000 hours operation in the first two years, the failure rate of the control system was less than 1%. However, we have experienced a few troubles which force the control system to stop more than a few hours. In addition, two-year operation provides us several suggestions to improve reliability on the control system. Based on the current experience, several kinds of improvements have been carried out or in progress. In this report, the recent improvements on various subjects, for example the redundancy on the hardware, are discussed.