CBI   Cosmic Background Imager  

Control Software

Control and data acquisition are divided between two computers, a real-time system running VxWorks1 on a single-board computer mounted in a VME crate2, and a Sun Microsystems3 workstation. The real-time system controls and monitors the CBI hardware via a VME backplane. Some 3000 registers, including the observed complex visibilities (10 channels times 78 baselines), are monitored every 0.8 s and sent via TCP/IP to the Sun. The Sun control program runs continuously and is responsible for data logging, executing commands received from users, and executing schedules written in a specially designed embedded scheduling language. A powerful user-interface program can be run on the same Sun or on a remote workstation. This is implemented as a set of C service functions layered under a Tcl/Tk graphical user interface (GUI) and provides real-time graphical and textual monitoring facilities, along with a command-line control interface. It can be used both to display the current instrumental status and to examine or replay archived log data. Archived data are transferred on magneto-optical disks to San Pedro for analysis.

Control computers
Two Sun workstations (primary control and backup) in the control room (October 1999). Extra cooling fans are required because of the low pressure; hard disks are enclosed in pressurized containers.
1 Wind River Systems
2MVME177, Motorola Inc
3Sun Microsystems Inc

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