Digital control of the LEP RF system

The RF system for the initial phase of LEP (Large Electron Positron collider) consists of eight identical units of 16 cavity assemblies with associated high-power and control equipment. Digital control is achieved by assigning a G64-based equipment controller crate to each major element of the unit. The crates are linked by a bus to a VME-based data manager with overall control and connection to the control network. The manager executes locally or remotely initiated complex control and surveillance procedures to simplify operation. The different classes of parameter and data are summarized. Interfacing and control within the equipment controllers and communication with the data manager are outlined. The equipment access functions and the development of complex control procedures are discussed. The implementation of corresponding functions at the control console level is examined. Experience with the six RF units presently installed is described. The modular approach to the controls of the LEP RF system, together with an interactive local control facility, has been found vital in commissioning and testing the RF system. It also allows additional units with superconducting cavities to be integrated gradually into the controls system with minimal disturbance to the operation of the accelerator