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Paper: A PLC Distributed Layout: the Case of the Instrument Control Electronics of ESPRESSO
Volume: 521, Astronomical Data Analysis Software and Systems XXVI
Page: 604
Authors: Baldini, V.; Calderone, G.; Cirami, R.; Coretti, I.; Cristiani, S.; Marcantonio, P. D.; Mégevand, D.; Riva, M.
Abstract: ESPRESSO, the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations of the European Southern Observatory (ESO) is passing the integration phase in Geneva before being shipped to Chile and installed at the Very Large Telescope (VLT) site on the Cerro Paranal. It is going to be one of the first permanent instruments of VLT with a distributed control electronics based on Beckhoff PLCs. About 40 motorized stages, more than 90 sensors and several calibration lamps are controlled by the Instrument Control Electronics (ICE) and Software (ICS). All the ESPRESSO functionalities are managed by two main CPUs that Sshare the workload. The Beckhoff EtherCAT decentralization modules ensure the EtherCAT continuity between the 7 PLC electronics subracks placed in different cabinets, allowing optimal distributed architecture. Furthermore, one of the two CPUs is equipped with an IEEE 1588 protocol interface, used for the time synchronization of the distributed clocks in the networks. In this paper the features of the CPUs used, the distribution of functions among them, the electronic cabinets configuration and a detailed overview of the PLC control system used are presented.
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