Front-end I/O of the ATLAS Detector Control System

The importance of using a powerful Detector Control System (DCS) has much increased with the size and complexity of High-Energy Physics detectors. The generation of detectors for the LHC experiments puts further requirements onto the front-end I/O system due to the inaccessibility of the equipment and the hostile environment concerning radiation and magnetic field. Novel techniques such as fieldbuses for distributed input/output and Programmable Logic Controllers (PLC) for closed loop control have to be employed. These represent the layer closest to the detector of a hierarchically organized multi-layer DCS. After an introduction of the organization of the ATLAS detector and of the concept and the architecture of DCS the paper will concentrate on the usage of fieldbuses as front-end I/O bus with special emphasis on industrial standards of hardware and software.