Design of the Distributed Control System for Beam Lines at the Photon Factory

A distributed control system has been designed to control all beam lines around the 2.5 GeV storage ring at the Photon Factory. It is a local area network composed of outlying nodes and a central node which are interconnected in a star configuration via optical fiber links, with a communication rate of 9600 baud. Each beam line is controlled by its own outlying node, independently of adjacent beam lines. The system is flexible and expandable enough to accommodate itself to variations in beam line features, according to experimental circumstances. In addition, when failure of a beam line occurs in the network, the system does not disrupt the rest of the beam line controls by disconnecting the defective line. The control scheme and network architecture are described, as well as the hardware configuration of the system.