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Proceedings Paper

The data flow system for the AAO2 controllers
Author(s): Keith Shortridge; Tony J. Farrell; Jeremy A. Bailey; Lewis G. Waller
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Paper Abstract

The AAO's new AAO2 detector controllers can handle both infra-red detectors and optical CCDs. IR detectors in particular place considerable demands on a data handling system, which has to get the data from the controllers into the data processing chain as efficiently as possible, usually with significant constraints imposed by the need to read out the detector in as smooth a manner as possible. The AAO2 controller makes use of a VME chassis that contains both a real-time VxWorks system and a UNIX system. These share access to common VME memory, the VxWorks system reading from the controller into the shared memory and the UNIX system reading it from the shared memory and processing it. Modifications to the DRAMA data acquisition environment's bulk-data sub-system hide this use of VME shared memory in the normal DRAMA bulk-data API. This means that the code involved can be tested under UNIX, using standard UNIX shared memory mechanisms, and then deployed on the VxWorks/UNIX VME system without any code changes being needed. When deployed, the data transfer from the controller via VxWorks into the UNIX-based data processing chain is handled by consecutive DMA transfers into and out of VME memory, easily achieving the required throughput. We discuss aspects of this system, including a number of the less obvious problems that were encountered.

Paper Details

Date Published: 15 September 2004
PDF: 6 pages
Proc. SPIE 5496, Advanced Software, Control, and Communication Systems for Astronomy, (15 September 2004); doi: 10.1117/12.550362
Show Author Affiliations
Keith Shortridge, Anglo-Australian Observatory (Australia)
Tony J. Farrell, Anglo-Australian Observatory (Australia)
Jeremy A. Bailey, Anglo-Australian Observatory (Australia)
Lewis G. Waller, Anglo-Australian Observatory (Australia)

Published in SPIE Proceedings Vol. 5496:
Advanced Software, Control, and Communication Systems for Astronomy
Hilton Lewis; Gianni Raffi, Editor(s)

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