The MAST data acquisition upgrade

摘要

A programme has begun on MAST to replace its ageing CAMAC and VME based data acquisition systems with new modern hardware which, together with several improvements in the supporting infrastructure, will provide support for faster data acquisition rates, longer-pulse operation, faster data access and higher reliability.rnThe main principle of the upgrade was to use commercial off-the-shelf (COTS) hardware and well-established standards wherever possible. CompactPCl or PXI was chosen as the digitiser form factor to replace CAMAC/VME, and Ethernet would be used as the means to access all devices.rnThe modular architecture of the MAST data acquisition software framework has helped to minimise the integration effort required to phase in new subsystems and/or new technologies whilst continuing to use the old hardware in other systems. The software framework was updated to allow more versatile use of the network-attached data acquisition devices.rnThe new data acquisition devices had multiple connector types, which created difficulties with the cable interfacing. To resolve this and provide support for easy substitution, a standard connector interface was chosen, based on the most common connector type and pin-out already in use, and several cable assemblies were produced to connect the proprietary interface of the digitiser to the standard interface block.rnThe in-house IDA-3 data storage format is unable to accommodate the larger file sizes and is increasingly difficult to maintain, so it is to be gradually phased out. The NetCDF-4/HDF5 data standard is being adopted as its replacement, thus reducing in-house maintenance whilst providing a data format that is more accessible to the Fusion community.rnSeveral other infrastructure upgrades were necessitated by the anticipated increase in data traffic and volume including the Central Timing System, the MAST Ethernet infrastructure and servers for front-end data processing, data storage and data access management.rnThese improvements have provided higher reliability, faster data retrieval, greater longevity and capacity to extend the MAST pulse length to accommodate the future programme requirements.