The read-out and control system of the DES camera (SISPI)

We describe the data acquisition and control system of the Dark Energy Camera (DECam), which will be the primary instrument used in the Dark Energy Survey (DES). DECam will be a 3 sq. deg. mosaic camera mounted at the prime focus of the Blanco 4m telescope at the Cerro-Tololo International Observatory (CTIO). The DECam data acquisition system (SISPI) is implemented as a distributed multi-processor system with a software architecture built on the Client-Server and Publish-Subscribe design patterns. The underlying message passing protocol is based on the SML inter-process communication software developed at CTIO [1]. For the DECam read-out and control system this software package was ported from LabVIEW to the Python and C programming languages. A shared variable system was added to support exchange of telemetry data and other information between different components of the system. In this paper we discuss the SISPI architecture, new concepts used in the design of the infrastructure software and provide an overview of the remaining components of the DES read-out and control system.