Control system of PLS 2-GeV electron linac

A graphic-based realtime control system is developed and used for commissioning and operation of the PLS 2-GeV electron linac. The system has three layers of hierarchy; operator interface computer, supervisory control computer (SCC) for data processing, and device interface computer (DIC) for distributed data acquisition. The operator interface is based on the UNIX system with a graphic-based development system named RTworks. The SCC consists of three subsystems; modulators, magnet power supplies, and beam diagnostics. DICs attached to individual devices are placed in the 200-m linac building. There are altogether 23 VME CPUs and various I/Os in both SCC and DIC levels. The realtime operating system is OS-9. The major role of DICs is to control and to monitor individual devices upon operator's requests. The SCC updates variable database from DICs and conveys commands from the operator to DICs. SCCs and DICs are connected through a local area network to form a client/server system. Low-cost workstations are used for the operator interface. In order to have quick manipulation and easy understanding, the authors use intensive graphics for the control windows