The electronic interface for control of the dedicated synchrotron radiation storage ring BESSY

The commercially available electronic interface system, called DEV 12 and the developed BESSY-standard I/O-cards and hardware tools are presented. The DEV 12 system is a simple bit parallel byte-serial data multiplexing system, connectable in a tree or chain structure. Six different types of I/O-cards were developed. 3/4 of all equipments are interfaced only by a single card. The rest uses combinations of several cards. For reading back analog signals the voltage to frequency conversion is used. The computer and equipments are multiple optically insulated from each other. Computer controlled knobs were developed, becoming the most important hardware for machine adjustment. For units without digital remote control capability an interface module called 'General Purpose Interface GPI' was built to match any equipment to the standard I/O-cards. An intelligent 'GPI' is in construction to get rid of any specialized type of equipment and part of the so far used interface system. The general design philosophy, the hardware structure, and the features of the control system hardware is given