Distributed Control System for the Test Interferometer of the ALMA Project

The control system (TICS) for the test interferometer being built to support the development of the Atacama Large Millimeter Array (ALMA)[1] will itself be a prototype for the final ALMA array, providing a test for the distributed control system under development. TICS will be based on the ALMA Common Software (ACS)[2] (developed at the European Southern Observatory), which provides CORBAbased[3] services and a device management framework for the control software. Simple device controllers will run on single board computers, one of which (known as an LCU) is located at each antenna; whereas complex, compound device controllers may run on centrally located computers. In either circumstance, client programs may obtain direct CORBA references to the devices and their properties. Monitor and control requests are sent to devices or properties, which then process and forward the commands to the appropriate hardware devices as required. Timing requirements are met by tagging commands with (future) timestamps synchronized to a timing pulse, which is regulated by a central reference generator, and is distributed to all hardware devices in the array. Monitoring is provided through a publish/subscribe CORBA-based service.