Overview of data acquisition system for SST-1 diagnostics

The recent first phase operations of SST-1 in short pulse mode have provided an excellent opportunity for the essential initial tests and benchmark of the SST-1 Data Acquisition System. This paper describes the SST-1 Data Acquisition systems (DAS), which with its heterogeneous composition and distributed architecture, aims to cover a wide range of slow to fast channels interfaced with a large set of diagnostics. The DAS also provides the essential user interface for data acquisition to cater both on and off-line data usage. The central archiving and retrieval service is based on a dual step architecture involving a combination of Network Attached Server (NAS) and a Storage Area Network (SAN). SST-1 Data Acquisition Systems have been reliably operated in the SST-1 experimental campaigns. At present different distributed DAS caters the need of around 130 channels from different SST-1 diagnostics and its subsystems. PXI based DAS and CAMAC based DAS have been chosen to cater the need, with sampling rates varying from 10Ksamples/sec to 1Msamples/sec. For these large sets of channels acquiring from individual diagnostics and subsystems has been a combined setup, subjected to a gradual phase of optimization and tests resulting into a series of improvisations over the recent operations. In order to facilitate a reliable data acquisition, the model further integrates the objects of the systems with the Central Control System of SST-1 using the TCP/IP communication. The associated DAS software essentially addresses the requirement of an active initialization of acquisition from SST-1 Central control and, subsequently, pushing the sampled data into the NAS for data archival using Ethernet. The focus is also on the need and implementation of loss-less data acquisition for various slow and fast SST-1 diagnostics channels along with synchronization of DAS elements with central timing system. The additional aspects of the system include a service subsystem responsible for data retrieval and analysis of diagnostics data, this integrates a facility to view diagnostics/subsystem signals across the network using a centralized MATLAB based plotting and analysis tool for the SST-1 diagnostics data.