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 (DIG) 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, we use intensive graphics for the control windows