Beamline Control at ESRF"

Francis Epaud
(ESRF)


The ESRF provided beam to beamlines at the end of 1992. Two and a half years later 14 beamlines (+ 4 CRG beamlines) are open to Users and regularly receive visiting scientists. 7 new beamlines are in their final commissioning phase and will be operational in early 1996. This rapid building schedule has been achieved by different small teams (hardware, front-end software, application software, etc. ) using exactly the same technologies for all the beamlines including the CRG (Collaborating Research Groups). VME front-ends hardware and software originally designed for the machine control system, based on the so called 'device server model', have been reused. This model uses client/server communication via RPC and runs on OS9 (and LynxOS) on the VME front-ends and Unix workstations. In the data acquisition domain, we are currently extending this model to define a 'Modular Data Acquisition Software' to handle the acquisition memories (AM) that are used to collect events or images. The main parts of this system are the 'online display' to visualise and evaluate rapidly the quality of the raw data collected inside the AM and the 'fast data transfer' to send rapidly the big amount of data (of the order of several hundreds of mega bytes) to a central computer facility (NICE) having large storage, computing and soon graphics capabilities. The transfer can be effected over Ethernet or ATM. The centralised computing facility (NICE) has been set up to allow short term data archiving and data treatment by means of dedicated file servers using RAID disk storage arrays, optical and magnetic tape robots for data migration and backup, and loosely coupled workstation cluster for data analysis and number crunching.