Data Acquisition Tasks Research Articles

MDSplus data acquisition system

MDSplus, a tree based, distributed data acquisition system, was developed in collaboration with the ZTH Group at Los Alamos National Lab and the RFX Group at CNR in Padua, Italy. It is currently in use at MIT, RFX in Padua, TCV at EPFL in Lausanne, and KBSI in South Korea. MDSplus is made up of a set of X/motif based tools for data acquisition and display, as well as diagnostic configuration and management. It is based on a hierarchical experiment description which completely describes the data acquisition and analysis tasks and contains the results from these operations. These tools were designed to operate in a distributed, client/server environment with multiple concurrent readers and writers to the data store. While usually used over a Local Area Network, these tools can be used over the Internet to provide access for remote diagnosticians and even machine operators. An interface to a relational database is provided for storage and management of processed data. IDL is used as the primary data analysis and visualization tool. IDL is a registered trademark of Research Systems Inc.

PC based ferroelectric analyzer using modified sawyer and tower circuit

Abstract Though several modifications and improvements have been made in past in the hysteresis loop tracer suggested by Sawyer and Tower, a more versatile PC based tracer with the facility to analyse the ferroelectric parameters is designed by looking at the present trend and requirement of computer automation. The use of a PC based automated ferroelectric analyzer, in addition to performing the tasks of measurement and plotting, is also utilised for extracting the ferroelectric parameters with more accuracy and speed. It also facilitates storage and retrieval of a large amount of data. Furthermore, the loop tracer designed using solid state integrated components reduces the complexity and bulkness. In this system, the output of the modified loop tracer is given to the 2 channels of a 12 bit successive approximation ADC card interfaced to PC instead of CRO in conventional circuits. A program written in BASIC and assembly languages implement the tasks of fastest data acquisition, file creation, plotting a...

Approximate performance analysis of real-time traffic over heavily loaded networks with timed token protocols

This paper studies timed token protocols with respect to real-time packet traffic in local area networks (LANs), such as FDDI and token bus, employed in distributed control systems. Typically, in such systems, three classes of packet traffic are encountered. The first class consists of packets cyclically generated by data acquisition tasks. The second traffic class is represented by packets generated in a random manner by control tasks and sporadic events. Finally, the third traffic class represents nonreal-time packet streams such as, for example, file transfers. To evaluate protocol performance, three performance measures are taken into account with respect to randomly generated real-time traffic: the mean waiting time, the blocking probability, and the probability that accepted packets will wait for service no longer than a specified time limit. In order to determine the last performance measure, a two-moment approximation of the waiting time distribution is applied. All three performance measures are evaluated at the beginning of the heavy network load region. Two examples of numerical calculations compared with computer simulations done for FDDI-II and token bus networks are given.

NeuroNet: collaborative intraoperative guidance and control

Neurophysiological monitoring assesses CNS structure function relationships during surgery. NeuroNet supports remote performance of this task through real time multimodal data processing and multimedia network communication. The system is fully integrated, transparently combining the collection, processing, and presentation of real time data sources, including all physiological monitoring functions, with non real time functions and extensive online database information. Workstations are mounted in instrumentation racks and configured with appropriate electronics to support various data acquisition tasks including electroencephalograms (EEGs), electromyograms (EMGs), and multimodality evoked potentials. Multiple racks can be used in parallel on the same case if the number of variables to be monitored exceeds the capacity of a single tack. The data acquired on these systems is transparently accessible, in real time, across the network for both review and analysis.

The RFX centralized control, data acquisition and machine protection systems

RFX employs a centralized approach to the tasks of control, monitoring, data acquisition and machine protection. In this paper we describe the requirements, the structure, the components, and the operation of the corresponding systems of RFX. To guarantee a high degree of reliability, a strict subdivision has been imposed from the very start, between the control, monitoring and data acquisition system SIGMA (“sistema di gestione, monitoraggio ed acquisizione dati”) and the global fast machine protection system SGPR (“sistema generale di protezione rapida”). SIGMA has been designed for the following signals: about 5000 slow, mostly digital, signals, which provide non-shot-related information from the plant and commands to the plant, and about 1000 channels of fast (2 kHz–1 MHz), shot-related data from the plant, which produce up to 20 Mbytes of data per shot. In addition, fast plant-wide timing signals (precision better than 10 μs) have to be provided. SIGMA employs two distinct technologies: industrial-type programmable controllers (PLCs) handle the slow signals; a centralized VAX-VMS computer cluster with front end according to the CAMAC standard takes care of the fast system components. The CAMAC-based system covers both the fast data acquisition and the timing requirements. Workstations are used as operator consoles for the fast part of the system; personal computers are used as consoles to the PLCs. All components of the system communicate via a single, fibre optic Ethernet. A single PLC acts as supervisor of the entire shot sequence. The PLCs are programmed in an assembler-type language at the lower level and in a language according to the grafcet standard at the higher level. The PC-based consoles employ a commercial package for plant monitoring and control. The VAX-based systems run a purpose-developed software package, known as mds-plus, which provides integrated operation of timing and fast data acquisition. mds-plus is a joint software development with the MIT Plasma Fusion Center and the Los Alamos National Laboratory. The machine protection system SGPR has to deal with up to 50 possible requests for fast intervention and to distribute the corresponding command signals with an overall reaction time of 1 ms. SGPR is based on dedicated hardware which implements decision logic for intervention requests of four different urgency levels. It despatches the intervention commands to the corresponding protective devices in the various local units. All signal paths and the decision logic are duplicated with continuous automatic checks for integrity. Single transmission from the sensors and to the protective devices is by duplicated fibre optic lines with continuous self-test. Operation of RFX is under complete control of SIGMA from a single, central control room. It houses the supervisor console, all subsystem consoles (PCs and workstations) as well as some additional equipment (SGPR display, printers, television equipment, etc.). Shot execution follows a strict sequence, which is implemented as a unique state machine on all subsystems (PLCs and VAX computers). The supervisor console is the operator interface to the system-wide state machine which controls the shot sequence. The performance of the system is considered satisfactory with scope for further improvement. The cycle time of the PLCs is below 200 ms; the picture update time on the PC-based consoles is below 3 s. The fast system acquires all channels (at the moment around 15 Mbytes of uncompressed data per shot) within around 10 min. This time includes the display of several hundreds of measurement channels on different workstations in the central control room, and the automatic execution of a number of data analysis programs.

The Transputer Based CCD Controller at ESO

A new controller concept based on transputer modules (TRAMs) and Digital Signal Processors (DSPs) has been developed at ESO. The Array Control Electronics (ACE) can handle single CCDs or CCD mosaics with 1 to 64 outputs and with up to 256 clocks with software programmable independent high and low voltages. The same basic concept will be used for slow scan scientific and fast scan auto guiding/wave front sensing applications. While the transputers are mainly used for data acquisition, communication and supervisory tasks, a DSP with very simple external logic performs the time-critical CCD clock pattern generation. The low noise, high speed clock driver with built-in telemetry is designed for highest operational safety. A newly designed video processor board has four video channels each with its own 16-bit ADC. ACE can easily be interfaced to various types of host computers like PCs, Unix workstations or ESO's VME-based LCUs (Local Control Units with VxWorks real-time operating system).

Transputer networks for the on-line analysis of fine-grained electromagnetic calorimeter data

Abstract Transputer networks, designed to perform parallel computations, are well suited for data acquisition, on-line analysis and second level trigger tasks in high energy physics experiments. Some simple algorithms for the analysis of fine-grained electromagnetic calorimeter data were implemented on two types of transputer networks and tested on real and simulated data from a silicon-tungsten calorimeter. Results are presented on the processing speed, measured in a test setup, and extrapolations to a full size detector and data acquisition system are discussed.

Hardware and software for a multiparametric concurrent data acquisition system

This paper presents a brief description of the basic characteristics and functioning of a simple hardware/software system for the simultaneous control of several data acquisition channels in atomic collisions experiments. The basic hardware consists of two IBM-PC/AT compatible boards equipped with ADCs, DACs, IO ports, and counters. The software allows simultaneous running of several data acquisition tasks, such as controlling an optical monochromator, an electrostatic energy analyzers and time-of-flight analyzers. The software also allows basic file input/output functions as well as some data processing functions.

An automated image metrology system

Abstract An automated, close-range, photogrammetric, digital image metrology system has been developed that accomplishes the extraction of geometrical information, in terms of three-dimensional coordinates of object points, from a stereopair of video images. The tasks of data acquisition and data reduction are carried out on-line and without delay or interruption. The hardware system consists of a television camera directly connected to a general image analysis computer system. The video signals from the camera were captured by the computer system, digitised into a 512 by 512 pixel array and 64 grey levels, stored in the computer memory and displayed for viewing. For data reduction, two methods for measuring digital image pixel coordinates were developed: manual method and automatic method. For comparison 35 mm photography were used.

A general purpose interactive programmable laboratory interface system using the IEEE-488 Bus

A programmable interface system, designed for general use in the laboratory, is described. The system is designed to be used as a peripheral on the IEEE-488 Instrumentation Bus and features an interactive Forth interpreter that allows for considerable flexibility in its applications. The system simplifies both hardware and software problems commonly encountered, in the design of data acquisition and control systems and makes them less dependent on specific features of the controlling computer. The interface system provides simple electrical connections that can be adapted to suit a wide range of instruments, and, through programming, the functionality of an interface system and its associated instruments can be tailored to particular situations. Several interface systems can operate simultaneously on the same bus, in which case a number of data acquisition or control tasks can be executed in parallel, each on a separate interface system CPU. The software implementation of the system is described in detail.

A simple algorithm for averaging multiple cycles of waveforms having varying cycle periods

We present a simple method for averaging multiple cycles of a waveform having cycles with varying periods. This averaging process preserves the morphology of the waveform by converting fixed time per point data into fixed fraction of cycle data. The algorithms are implemented using the ASYST system, which provides efficient code for performing the computations and permits straightforward integration of the data acquisition and analysis tasks. An example is given of the results of the program in processing cyclical waveforms obtained in respiratory research.

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A changing philosophy in seismic data acquisition

The primary task of seismic data acquisition is to produce a data set from which the recorded wavefield can be reconstructed at any time and at any place with maximum fidelity. This should be followed in the processing phase by the full inversion of the wavefield in order to reconstruct our exploration targets. The technical requirement for such acquisition is a spatially wide-band recording system with minimum distortion. As far as possible, the desired and undesired events should remain separable, and the ability to correct for imperfections should be retained. Traditionally, one task of seismic data acquisition has been to immediately commence improvements of the apparent signal-to-noise ratio in the field. The main tools for this have been the use of geometrical shot and receiver arrays to suppress dominant noise arrivals. Unfortunately this has usually been done by comparing field records acquired with different experimental parameters, but without the primary physical objectives kept in mind. Neither spatial distortion, whether linear or non-linear nor the spatial or temporal separability of wanted and unwanted events, can be assessed by looking at raw field records. The physics of the discrete recording, anti-alias filtering and re-sampling, with the objective of maintaining the information within a defined bandwidth, is well known, in particular for time series. There is no reason why spatial samples should not be handled in the same way as temporal samples. Therefore, one could record spatially with an essentially similar approach to that used for the time domain, and provide selectivity later in the subsequent processing phase. This would simplify the data acquisition to a general measuring system and would provide endless processing possibilities without initial acquisition commitment. In addition a high degree of standardization would be obtained. Such a system for 'hands-off' acquisition was described by Ongkiehong and Askin (1988) and has already been implemented in worldwide operations. Additional hardware developments could make this method and any other seismic system even more powerful.

The MC68020-Based FASTBUS Read-Out Processor of the Aleph Time Projection Chamber

72 double-width Fastbus modules, built around a MC68020 processor, are used in the read-out of the TPC (Time Projection Chamber) of the Aleph experiment at CERN, Geneva. They perform basic data acquisition tasks as well as processing of events and monitoring of the set-up. A very fast and original Fastbus coprocessor has been developed. Performance of the module and problems related to the complexity of the system are discussed.

A data acquisition, display and plotting program for the IBM PC

A program, AQ, has been developed to perform analog-to-digital (A/D) conversions on IBM PC products using the Data Translation DT2801-A or DT2801 boards. This program provides support for all of the triggered and continuous A/D modes of these boards. Additional subroutines for management of data files and display of acquired data have also been developed. These programs have been written so that a minimum number of keystrokes are required for their operation. Parameter files are used to simplify reconfiguration of this program for various data acquisition tasks.

Computer systems for laboratory networks and high-performance NMR.

Modern computer technology is significantly enhancing the associated tasks of spectroscopic data acquisition and data reduction and analysis. Distributed data processing techniques, particularly laboratory computer networking, are rapidly changing the scientist's ability to optimize results from complex experiments. Optimization of nuclear magnetic resonance spectroscopy (NMR) and magnetic resonance imaging (MRI) experimental results requires use of powerful, large-memory (virtual memory preferred) computers with integrated (and supported) high-speed links to magnetic resonance instrumentation. Laboratory architectures with larger computers, in order to extend data reduction capabilities, have facilitated the transition to NMR laboratory computer networking. Examples of a polymer microstructure analysis and in vivo 31P metabolic analysis are given. This paper also discusses laboratory data processing trends anticipated over the next 5-10 years. Full networking of NMR laboratories is just now becoming a reality.

A High-Speed CAMAC Data Acquisition System for PDP-11

This paper describes a high-speed data acquisition system for a PDP-11 running under the RSX-11M operating system. It has been used by several high-energy physics experiments at Fermilab. The system consists of several coordinated tasks which acquire data through a CAMAC interface, log data to magnetic tape, supply data to independent monitoring and analysis tasks (such as RSXMULTI), and perform control functions. A data buffer extending beyond the 18-bit address space of the PDP-11 is implemented using Konelar bank-switchable memory. Supported configurations range from small systems with single data acquisition and analysis tasks on the same processor, to large multi-processor systems with data acquisition on several PDPs and analysis on separate PDPs or VAXs.

Defect structure analysis of polycrystalline materials by computer-controlled double-crystal diffractometer with position-sensitive detector

The method represents an extension of a previously developed X-ray double-crystal diffractometer method when a film was used to record the crystallite reflections, each reflecting crystallite being regarded as the second crystal of a double-crystal diffractometer. By utilizing a position-sensitive detector (PSD) with interactive computer controls, the tedious and limiting task of data acquisition and analysis is greatly simplified. The specimen is irradiated with crystal-monochromated radiation and the numerous microscopic spots emanating from the reflecting crystallites are recorded separately by the position-sensitive detector and its associated multichannel analyzer at each increment of specimen rotation. An on-line minicomputer simultaneously collects these data and applies the necessary corrections. This process is then automatically repeated through the full rocking-curve range. The computer carries out the rocking-curve analysis of the individual crystallite reflections as well as that of the entire reflecting crystallite population. The instrument is provided with a specimen translation device which permits analysis of large sections of solid specimens. Thus, sites of local lattice defects induced either mechanically, chemically or by radiation can rapidly be established and quantitatively determined in terms of rocking-curve parameters as well as imaged by X-ray topography, by inserting a film in front of the PSD. The versatility and usefulness of the method is demonstrated by examples given from studies of fracture, fatigue and stress-corrosion cracking of commercial alloys.

TRIUMF's Data Acquisition System

A flexible data acquisition system consists of a data acquisition task which is coupled to and under control of, a data analysis task. The data acquisition task is designed to interface to CAMAC through one or more Kinetic Systems 3912 Type A Crate Controllers to a Digital Equipment PDP-11/34, and it configures itself at the beginning of each run according to a user-written CAMAC definition file. The data analysis task is a modified version of the Fermilab Multi Channel Histogram Program. It controls the flow of the data acquisition task, and also serves as a multi channel pulse height analyzer.

High speed front-end processing in the CAMAC interfacing system

In this paper, recent work in the design and application of bit-sliced microprocessor elements to front-end processing in data acquisition and control systems is discussed. A microprogrammed computing structure, based on commercially available Schottky TTL microprocessor slices, performs high speed subroutines at a basic operation time of 142 ns per microcycle. The structure operates in parallel with, and under the control of, a conventional microcomputer system, which is generally interfaced to a more complete system-minicomputer that actually performs the data acquisition or control task.