A FULLY COMPUTERIZED AND DISTRIBUTED VME SYSTEM FOR CONTROL AND DATA-ACQUISITION ON THE TOKAMAK ISTTOK

The ISTTOK operation and research programme require a very reliable co ntrol and data acquisition system due to the pulsed nature of the toka mak discharges. This system (SCAD) was designed in a distributed, modu lar, multivendor, integrated and transparent approach, taking advantag e of recent improvements in networking, front-end processing and datab ase management. This paper reports some of the most relevant aspects i nvolved in the design of the SCAD current configuration. The computer system is based on personal computers (PCs) and Motorola 68000 family microprocessors, linked by an ethernet local area network. Control is made by a vacuum controller unit as well as by VME digital I/O, timing and digital-to-analog converter modules. Data acquisition is provided by VME instrumentation as well as by PC based modules and by a digiti zing oscilloscope. All VME modules were developed on site. The ISTTOK operation is controlled by a supervisory program. Data from the engine ering and physics diagnostics is stored in a central database.