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Proceedings Paper

Software control of the Advanced Technology Solar Telescope enclosure PLC hardware using COTS software
Author(s): Alastair J. Borrowman; Lander de Bilbao; Javier Ariño; Gaizka Murga; Bret Goodrich; John R. Hubbard; Alan Greer; Chris Mayer; Philip Taylor
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Paper Abstract

As PLCs evolve from simple logic controllers into more capable Programmable Automation Controllers (PACs), observatories are increasingly using such devices to control complex mechanisms1, 2. This paper describes use of COTS software to control such hardware using the Advanced Technology Solar Telescope (ATST) Common Services Framework (CSF). We present the Enclosure Control System (ECS) under development in Spain and the UK. The paper details selection of the commercial PLC communication library PLCIO. Implemented in C and delivered with source code, the library separates the programmer from communication details through a simple API. Capable of communicating with many types of PLCs (including Allen-Bradley and Siemens) the API remains the same irrespective of PLC in use. The ECS is implemented in Java using the observatory's framework that provides common services for software components. We present a design following a connection-based approach where all components access the PLC through a single connection class. The link between Java and PLCIO C library is provided by a thin Java Native Interface (JNI) layer. Also presented is a software simulator of the PLC based upon the PLCIO Virtual PLC. This creates a simulator operating below the library's API and thus requires no change to ECS software. It also provides enhanced software testing capabilities prior to hardware becoming available. Results are presented in the form of communication timing test data, showing that the use of CSF, JNI and PLCIO provide a control system capable of controlling enclosure tracking mechanisms, that would be equally valid for telescope mount control.

Paper Details

Date Published: 24 September 2012
PDF: 9 pages
Proc. SPIE 8451, Software and Cyberinfrastructure for Astronomy II, 84510I (24 September 2012); doi: 10.1117/12.927005
Show Author Affiliations
Alastair J. Borrowman, Observatory Sciences Ltd. (United Kingdom)
Lander de Bilbao, IDOM (Spain)
Javier Ariño, IDOM (Spain)
Gaizka Murga, IDOM (Spain)
Bret Goodrich, National Solar Observatory (United States)
John R. Hubbard, National Solar Observatory (United States)
Alan Greer, Observatory Sciences Ltd. (United Kingdom)
Chris Mayer, Observatory Sciences Ltd. (United Kingdom)
Philip Taylor, Observatory Sciences Ltd. (United Kingdom)


Published in SPIE Proceedings Vol. 8451:
Software and Cyberinfrastructure for Astronomy II
Nicole M. Radziwill; Gianluca Chiozzi, Editor(s)

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