VME Data Research Articles

The data acquisition system of the RFX tomographic diagnostic

The VME data acquisition system is described for a new tomographic diagnostic currently under development at the RFX nuclear fusion experiment. The system architecture, and its integration into the existing Control and Data Acquisition System of RFX is presented. A modelling approach in the definition and analysis of the distributed software architecture is then discussed. Finally the user interface requirements of the system and the implemented solutions are presented. I. INTRODUCTION RFX is a large magnetic confinement, nuclear fusion experiment currently in operation in Padova, Italy at the Istituto Gas Ionizzati of CNR [ll. Measurement of the intensity of soft X-ray and bolometric emission from the plasma in a fusion device can be related to properties such as plasma position, shape, impurity distribution, and magnetohydrodynamic phenomena. The use of tomographic methods, which provide multiple views of plasma emissivity along chords through a plasma crosssection, allows for the reconstruction of the spatial distribution of the plasma emissivity. In RFX, plasma emission is measured along up to 78 chords during the plasma pulse which can last up to 250 ms and is repeated about every 10 minutes. Due to the limited number of plasma emission views, the tomographic procedures implemented for plasma emissivity reconstructions do not use finite element techniques as used in medical tomography, rather a least square approach of analytic solutions of the Radon transform constructed using base function expansions: Fourier series for the angular components of the emissivity, various base function expansions for its radial components depending on the kind of inversion implemented [2]. The result of a tomographic inversion is therefore a set of parameters to be used in the chosen angular and radial expansions of the emissivity function. Due to the limitation in the number of angular harmonics and in the maximum order of the radial expansion functions, which are related to geomeVic factors in the chord displacements, the number of such parameters is usually much less than the number of acquired views, and the results of the tomographic inversion form a more compact representation of the information produced by the diagnostic. The interpretation of such results requires however much care because of the finite order of the harmonic expansion which causes aliasing of any unresolvable features and produce unavoidable artefacts. For this reason, multiple tomographic inversions, based on different function expansions, are required in order to obtain a 0018-9499/96$05

A 100 MHz VME data acquisition system

A VME based 100 MSPS data acquisition system with four independent input channels and timing capability is presented. Data describing the performance of the system is also shown. Discussion is focused on the use of recently delivered devices, flash ADCs and high speed FIFO memories, configured in a data acquisition architecture, which takes advantage of the features inherent to those new devices.

Development of a Unix/VME data acquisition system

The current status of a Unix-based VME data acquisition development project is described. It is planned to use existing Fortran data collection software to drive the existing CAMAC electronics via a VME CAMAC branch driver card and associated Daresbury Unix driving software. The first usable Unix driver has been written and produces single-action CAMAC cycles from test software. The data acquisition code has been implemented in test mode under Unix with few problems and effort is now being directed toward finalizing calls to the CAMAC-driving software and ultimate evaluation of the complete system.

Initial operation and current status of the fermilab D0 VME-based hardware control and monitor system

D0 is a large colliding-beam detector at Fermilab. The control system for this detector includes 25 VMEbus-based 68020 computers interconnected using the IEEE-802.5 token-ring local-area network. In operation, the system will monitor about 15000 analogue channels and several thousand digital status bits, interfaced to the 68020 computers by the MIL/STD-1553B multiplexed data bus. In addition, the VME control system uses a memory-mapped multi-VMEbus interconnect to download parameters to more than 100 VME data crates in the experiment. Remote host computers can then read and set memory in the detector crates over the network by accessing memory in the control crates. This is an extremely useful feature during the construction phase, because low-level diagnostics and testing of all the detector electronics can be done over the token-ring network using either IBM-PC compatible computers or the laboratory-wide VAX system. The VME control-system hardware is now being installed in the D0 moveable counting house. Installation is expected to be complete later this year.

A distributed VME control system for the LISA superconducting linac

The control and diagnostic system for LISA, a new accelerator under construction, is presented. The system is based on a multiprocessor environment and uses interactive graphical workstations and the VME data acquisition standard. Particular care has been given to the operator-machine interface. A strict hierarchical structure has been designed into the system for reliability and flexibility. The discussion focuses on the structure of the control system, the hardware architecture, and the software environment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

MANDA system: A VME data acquisition system for nuclear physics experiments

The authors consider the MANDA (Multiprocessor Applied to Nuclear Data Acquisition) systems. They describe the running version of the system, which has been coupled to a double front-end. The data-sorting in this case is accomplished by hardware using CAMAC histogramming memories. Software data analysis is available on the Vaxstation. Some development details concerning the coupling with new front ends and the VME online data analysis system are given.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The UA1 VME data acquisition system

The data acquisition system of a large-scale experiment such as UA1, running at the CERN proton-antiproton collider, has to cope with very high data rates and to perform sophisticated triggering and filtering in order to analyze interesting events. These functions are performed by a variety of programmable units organized in a parallel multiprocessor system whose central architecture is based on the industry-standard VME/VMXbus.