Status of ESO Very Large Telescope Control Software

G.Raffi
European Southern Observatory (ESO), Germany


The Very Large Telescope (VLT) project consists of four 8 m diameter telescopes to be installed at a new observatory in the Atacama desert in Chile. Extensive tests involving hardware and software will start at the observatory and in Europe next year, but the whole commissioning will extend well after year 2000.

The control software architecture for the VLT project was introduced at the ICALEPCS '91 Conference. The size of the control software was estimated to be equivalent to 200 man-years of development and about 1 - 1.2 million of lines of code, to be implemented partly in collaboration with industries and astronomical institutes.

The ESO team has created a central layer of software on top of a Standard Architecture, based on Unix and VxWorks and on a commercial industrial control package, including a real-time database. This layer of software amounts by now to more than 400.000 lines of code.

The introduction of an object-oriented event-driven architecture in the control software is one of the recent and most promising developments (reported in a separate paper at this Conference). Other interesting developments concern the usage of Tcl/Tk in the implementation of a Sequencing tool and of a Panel editor, which allows to create homogeneous user interfaces for telescopes and instruments.

The experience and evolution of concepts in the VLT control software are reported, with emphasis on the goal of maintaining consistency while adapting to new technologies.