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Proceedings Paper

Control system of the VLT Interferometer
Author(s): Massimo Verola
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Paper Abstract

During an interferometric observation the successful coordination of all the complex and heterogeneous devices of the VLT interferometer (VLTI) depends on the effectiveness and reliability of the control system, which carries out the ultimate system integration. The VLTI control system (VLTICS) is designed to satisfy both specific technical requirements and general operational constraints. It profits by the valuable experience gained during the development of the control system for the VLT 8-m Unit Telescopes, inheriting the same principles and standards. Since the VLTICS is a direct client of the TCS, the homogeneous architecture simplifies the interface definition and the data communication protocol. Therefore we can focus on the identification of those functions that are peculiar to VLTI and work out the most challenging requirements. The VLTICS architecture is implemented and integrated within the framework of the VLT Observatory control environment. It relies on two hardware platforms; real-time VME control nodes and UNIX-based workstations. The VME nodes provide the interface to the controlled devices and run the data acquisition and digital control algorithms, while the workstations are used for coordinating and monitoring tasks, on-line database facility and graphical user interface. The standard control network is optical fiber Ethernet. ATM LAN links support image data transfer between the detectors and the workstation. In order to achieve the performance required by the fringe control loop, we have adopted the reflective memory technology, which offers a zero-latency deterministic data link with no software protocol overhead. This paper describes the basic requirements and the overall architecture of the VLTICS, the software design method and the interfaces towards external system and software clients. It draws also a parallel between VLTICS and TCS with respect to the main functions provided.

Paper Details

Date Published: 24 July 1998
PDF: 9 pages
Proc. SPIE 3350, Astronomical Interferometry, (24 July 1998); doi: 10.1117/12.317102
Show Author Affiliations
Massimo Verola, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 3350:
Astronomical Interferometry
Robert D. Reasenberg, Editor(s)

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