Distributed Data Acquisition System Research Articles

Monitoring the CMS data acquisition system

The CMS data acquisition system comprises O(20000) interdependent services that need to be monitored in near real-time. The ability to monitor a large number of distributed applications accurately and effectively is of paramount importance for robust operations. Application monitoring entails the collection of a large number of simple and composed values made available by the software components and hardware devices. A key aspect is that detection of deviations from a specified behaviour is supported in a timely manner, which is a prerequisite in order to take corrective actions efficiently. Given the size and time constraints of the CMS data acquisition system, efficient application monitoring is an interesting research problem. We propose an approach that uses the emerging paradigm of Web-service based eventing systems in combination with hierarchical data collection and load balancing. Scalability and efficiency are achieved by a decentralized architecture, splitting up data collections into regions of collections. An implementation following this scheme is deployed as the monitoring infrastructure of the CMS experiment at the Large Hadron Collider. All services in this distributed data acquisition system are providing standard web service interfaces via XML, SOAP and HTTP [15,22]. Continuing on this path we adopted WS-* standards implementing a monitoring system layered on top of the W3C standards stack. We designed a load-balanced publisher/subscriber system with the ability to include high-speed protocols [10,12] for efficient data transmission [11,13,14] and serving data in multiple data formats.

Developing strategies for automated remote plant production systems: Environmental control and monitoring of the Arthur Clarke Mars Greenhouse in the Canadian High Arctic

The Arthur Clarke Mars Greenhouse is a unique research facility dedicated to the study of greenhouse engineering and autonomous functionality under extreme operational conditions, in preparation for extraterrestrial biologically-based life support systems. The Arthur Clarke Mars Greenhouse is located at the Haughton Mars Project Research Station on Devon Island in the Canadian High Arctic. The greenhouse has been operational since 2002. Over recent years the greenhouse has served as a controlled environment facility for conducting scientific and operationally relevant plant growth investigations in an extreme environment. Since 2005 the greenhouse has seen the deployment of a refined nutrient control system, an improved imaging system capable of remote assessment of basic plant health parameters, more robust communication and power systems as well as the implementation of a distributed data acquisition system. Though several other Arctic greenhouses exist, the Arthur Clarke Mars Greenhouse is distinct in that the focus is on autonomous operation as opposed to strictly plant production. Remote control and autonomous operational experience has applications both terrestrially in production greenhouses and extraterrestrially where future long duration Moon/Mars missions will utilize biological life support systems to close the air, food and water loops. Minimizing crew time is an important goal for any space-based system. The experience gained through the remote operation of the Arthur Clarke Mars Greenhouse is providing the experience necessary to optimize future plant production systems and minimize crew time requirements. Internal greenhouse environmental data shows that the fall growth season (July–September) provides an average photosynthetic photon flux of 161.09 μmol m −2 s −1 (August) and 76.76 μmol m −2 s −1 (September) with approximately a 24 h photoperiod. The spring growth season provides an average of 327.51 μmol m −2 s −1 (May) and 339.32 μmol m −2 s −1 (June) demonstrating that even at high latitudes adequate light is available for crop growth during 4–5 months of the year. The Canadian Space Agency Development Greenhouse [now operational] serves as a test-bed for evaluating new systems prior to deployment in the Arthur Clarke Mars Greenhouse. This greenhouse is also used as a venue for public outreach relating to biological life support research and its corresponding terrestrial spin-offs.

Configuration and supervision of advanced distributed data acquisition and processing systems for long pulse experiments using JINI technology

The development of tools for managing the capabilities and functionalities of distributed data acquisition systems is essential in long pulse fusion experiments. The intelligent test and measurement system (ITMS) developed by UPM and CIEMAT is a technology that permits implementation of a scalable data acquisition and processing system based on PXI or CompactPCI hardware. Several applications based on JINI technology have been developed to enable use of this platform for extensive implementation of distributed data acquisition and processing systems. JINI provides a framework for developing service-oriented, distributed applications. The applications are based on the paradigm of a JINI federation that supports mechanisms for publication, discovering, subscription, and links to remote services. The model we implemented in the ITMS platform included services in the system CPU (SCPU) and peripheral CPUs (PCPUs). The resulting system demonstrated the following capabilities: (1) setup of the data acquisition and processing to apply to the signals, (2) information about the evolution of the data acquisition, (3) information about the applied data processing and (4) detection and distribution of the events detected by the ITMS software applications. With this approach, software applications running on the ITMS platform can be understood, from the perspective of their implementation details, as a set of dynamic, accessible, and transparent services. The search for services is performed using the publication and subscription mechanisms of the JINI specification. The configuration and supervision applications were developed using remotely accessible (LAN or WAN) objects. The consequence of this approach is a hardware and software architecture that provides a transparent model of remote configuration and supervision, and thereby a means to simplify the implementation of a distributed data acquisition system with scalable and dynamic local processing capability developed in a fusion environment.

Implementation of local area network extension for instrumentation standard trigger capabilities in advanced data acquisition platforms

Synchronization mechanisms are an essential part of the real-time distributed data acquisition systems (DASs) used in fusion experiments. Traditionally, they have been based on the use of digital signals. The approach known as local area network extension for instrumentation (LXI) provides a set of very powerful synchronization and trigger mechanisms. The Intelligent Test Measurement System (ITMS) is a new platform designed to implement distributed data acquisition and fast data processing for fusion experiments. It is based on COMPATPCI technology and its extension to instrumentation (PXI). Hardware and software elements have been developed to include LXI trigger and synchronization mechanisms in this platform in order to obtain a class A LXI instrument. This paper describes the implementation of such a system, involving the following components: commercial hardware running a Linux operating system; a real-time extension to an operating system and network (RTAI and RTNET), which implements a software precision time protocol (PTP) using IEEE1588; an ad hoc PXI module to support hardware implementation of PTP-IEEE 1588; and the multipoint, low-voltage differential signaling hardware LXI trigger bus.

Synchronous Demodulator for Autonomous Sensors

In this paper, a novel differential synchronous demodulator is presented that uses the on-off switching characteristic of the power supply in autonomous systems as the control signal for demodulation. The proposed circuit, which uses only an op amp and a double-pole double-throw switch, can be useful in sensor nodes for sensor networks or distributed data-acquisition systems involving ac sensors or impedance measurements. Three prototype demodulators have been implemented using op amps with different power-bandwidth characteristics, and their common-mode rejection ratio (CMRR), nonlinearity, and initial transient were characterized. The working of the circuit when supplied by a piezoelectric energy converter is also verified.

Prototype of linac BLM at NSRL

A prototype of the Beam Loss Monitoring (BLM) System for the linac and transportation line has been built up in National Synchrotron Radiation Laboratory. Different from the storage ring, the radiation field around linac and transportation line have a duty factor of 10 −6 and a dose rate of hundreds Gy/h. The Monte-Carlo calculation gave the dose, flux, energy and direction distributions of the radiation field. According to the simulation result, the proper type of detector was chosen and the installation positions were selected accordingly. The widely used ionization chamber is not suitable to give accurate and real-time information of beam loss due to its large dimension and slow respond speed. Several PIN silicon diode-based detectors were designed and tested, and a charge-balanced integrating amplifier circuit was applied to read out the charge. A distributed data acquisition system based on embedded Ethernet technology was implemented in the prototype, which can offer a web server from the microcontroller. From preliminary tests, this new prototype was proved to be sensitive to the change of the linac status, and is a useful tool for monitoring and adjusting machine parameters. Further analyses are required to achieve a more accurate measurement of the beam loss.

Internet-Based Distributed Data Acquisition System for Fiber-Optic Sensors

This paper describes an internet-based distributed data-acquisition system for fiber-optic pressure sensors. There is a great need in industry to coordinate remote resources to perform a common task. The architecture described is based on remote access, via the internet, to a large number of fiber-optic pressure sensors located in different geographical areas. Distribution is done with server applications, which schedule requests for service and control the actual sensor device. Servers also detect conflicts between new requests and their current schedules. Client applications act as virtual instrument panels that dispatch measurement tasks for servers. The architecture supports multiple sensors, which can be added/removed from the system dynamically. As well, there can be multiple clients attempting to access servers simultaneously. Thus, the sensors in question are publicly shared among the various active client applications

Ethernet Based Distributed Data Acquisition System for a Small Animal PET

We report on the design of a small animal PET scanner being developed at our institutes. The existing setup is the first version of the miniPET machine consisting of four detector modules. Each detector module consists of an 8times8 LSO scintillator crystal block, a position sensitive photomultiplier, a digitizer including a digital signal processing board and an Ethernet interface board. There is no hardware coincidence detection implemented in the system and coincidence is determined based on a time stamp attached to every event by a digital CFD algorithm. The algorithm is implemented in the digital signal processing board and generates a time stamp with a coincidence resolution of less than 2 ns. The data acquisition system is based on Ethernet network and is highly scalable in size and performance

Investigation of crack sizing using ultrasonic phased arrays with signal processing techniques

Conventional ultrasonic array technology has limitations associated with detection and sizing of defects, particularly for difficult structures such as the carbon fibre composites and titanium composites used widely for construction of aircraft components. This paper describes an investigation of data acquisition and signal processing techniques for crack sizing using electronically-scanned ultrasonic linear arrays. The data acquisition technique involves aperture number variance (that is, varying the number of active elements on the array) and the use of full raw data (FRD) capture. FRD capture accumulates the time domain responses from each transmitter-receiver pair manipulated on the array. With FRD capture, the raw data is collected from the array probe and reconstructed to produce a real-time image during the scan. However, the full data set is also stored and so beam steering and focusing become features of post-processing analysis. Experimental results obtained from an ultrasonic array inspection of difficult materials with and without FRD capture are compared for detection capability and precision of simulated crack sizing. A detailed description of the distributed data acquisition system has been described previously.

Approach to improving network capable application processor based on IEEE 1451 standard

The IEEE 1451 standard supports the structure of distributed data acquisition systems and networks. The key components for such a distributed network are the Network Capable Application Processor (NCAP), Smart Transducer Interface Module (STIM), and the communication interface between them. This paper proposes an approach to improve the NCAP by introducing the functions of on-line dynamic reprogramming of the NCAP and software-programmable interface to support the most widely used communication interfaces between the NCAP and STIM via the network. Experimental research results of the proposed approach applying software-programmable interfaces, application examples of the proposed NCAP, and benefits of the applications are presented in the paper.

A TCP/IP transport layer for the DAQ of the CMS experiment

The CMS collaboration is currently investigating various networking technologies that may meet the requirements of the CMS Data Acquisition System (DAQ). During this study, a peer transport component based on TCP/IP has been developed using object-oriented techniques for the distributed DAQ framework named XDAQ. This framework has been designed to facilitate the development of distributed data acquisition systems within the CMS Experiment. The peer transport component has to meet 3 main requirements. Firstly, it had to provide fair access to the communication medium for competing applications. Secondly, it had to provide as much of the available bandwidth to the application layer as possible. Finally, it had to hide the complexity of using non-blocking TCP/IP connections from the application layer. This paper describes the development of the peer transport component and then presents and draws conclusions on the measurements made during tests. The major topics investigated include: blocking versus non-blocking communication, TCP/IP configuration options, multi-rail connections.

CAMAC, VXI, and PXI hybrid data acquisition system with MDSplus

The Hanbit mirror device is equipped with three kinds of data acquisition hardware: CAMAC; VME eXtensions for instrumentation (VXI); and PCI eXtensions for instrumentation (PXI). This hybrid system is managed by several MDSplus servers that are linked across a standard TCP/IP network. Each server directly acquires data from one or two frames of digitizers, analyzes data, and then archives them onto a hard disk to produce a high performance distributed data acquisition system (DAS). CAMAC modules are controlled by a Dec Alpha computer through the drivers provided together with MDSplus. Only small number of VXI and PXI drivers have been available until now. Therefore, an application is developed in C which utilizes the manufacturer-provided drivers for VXI and PXI. By sending commands to the application, MDSplus indirectly controls VXI and PXI. This paper will describe how the whole system is integrated and how it is controlled in a centralized manner.

A coding and On-Line Transmitting System

A distributed data acquisition system is proposed. It provides parallel and simultaneous coding and on-line transmission of signals. This system has higher accuracy of measurements and performance in sampling and transmission than known analogs.

Instrumentation for gathering data [DAQ systems

The main characteristic of the intelligent distributed data acquisition system we describe in this article is that it supports intelligent functions and provides the desired accuracy of measurement. It is also reliable and adaptable, utilising two NN-based methods of sensor drift prediction, which allows it to increase its inter-testing interval, and provides accuracy of sensor data processing. The system is designed on a distributed intelligence scheme, which operates in real time for most industrial sensors.

Remote Control for the HT-7 Distributed Data Acquisition System

HT-7 is the first superconducting tokamak device for fusion research in China. Many experiments have been done in the machine since 1994, and lots of satisfactory results have been achieved in the fusion research field on HT-7 tokamak [1]. With the development of fusion research, remote control of experiment becomes more and more important to improve experimental efficiency and expand research results. This paper will describe a RCS (Remote Control System), the combined model of Browser/Server and Client/Server, based on Internet of HT-7 distributed data acquisition system (HT7DAS). By means of RCS, authorized users all over the world can control and configure HT7DAS remotely. The RCS is designed to improve the flexibility, opening, reliability and efficiency of HT7DAS. In the paper, the whole process of design along with implementation of the system and some key items are discussed in detail. The System has been successfully operated during HT-7 experiment in 2002 campaign period.

Optimization of DC resistivity data acquisition: real-time experimental design and a new multielectrode system

With the recent introduction of multielectrode acquisition systems and twoand three-dimensional imaging software, there has been a marked increase in the use of direct-current (DC) resistivity techniques for addressing a wide variety of environmental, hydrogeological, and engineering issues. To determine the location and physical characteristics of relatively small targets distributed over wide areas, deployments of laterally extensive arrays of densely spaced electrodes for long recording periods may be required. For many academic and commercial projects, such large expenditures of effort are not plausible. We introduce the concept of real-time experimental design, in which relatively limited datasets that contain the most important subsurface information are recorded in a cost-optimized sense. Real-time experimental design, which involves a number of acquisition - data analysis - update survey design cycles, requires highly flexible recording equipment. To meet this need, we have developed a distributed data acquisition system in which waveforms are digitized and partially processed at each electrode before being rapidly transmitted to a central computer for storage, further processing, display, and preliminary interpretation. The individual data acquisition unit at each electrode has a high input impedance and a large dynamic range that ensures the recording of high-quality digital data. Versatile software controls the functions of all electrodes (e.g. whether they operate as current or potential electrodes) and the waveform of the transmitted current.

Corba technology in reengineering the FTU data acquisition system

In its early stages, Frascati tokamak upgrade DAS was essentially devoted to acquiring data from experiments in CAMAC standard, using a software system (code and database) entirely written by domestic professionals. In 15 years of life DAS has been growing in size and complexity, still preserving its original structure; at the same time new standards were introduced (VME, PCI) to take into account users’ ever increasing demands for amount of data and acquisition frequency with which the existing code couldn't cope. Moreover, machines were getting old and the maintenance became troublesome. Finally, the data archive porting to Unix has definitely shown that the DAS system was ageing and a thorough redesign was needed. The system we are planning to introduce is founded on a standard corba bus: (i) to integrate heterogeneous platforms and define a standard layer for interactions between the different acquisition units; (ii)to grant, with open source tools (MySql) and interfaces (Html and Java), unified access to hardware and software configuration data. So, a dedicated PC server, connected via a suitable PCI serial highway driver card, will perform the CAMAC access for all the clients interacting through the corba layer. Up to now we have successfully tested CAMAC access, and we designed an acquisition unit, which will be the building block of the new system. The next step will be migrating to Alpha/VMS the software related to CAMAC data acquisition, which has been so far the cornerstone of the whole DAS; it will be completely redesigned to fit the ‘acquisition unit’ paradigm we have defined. Finally we will have a fully distributed data acquisition system with VME (at present six such units have been operating since 1999) and PCI stations, an Alpha/VMS client of the CAMAC/PC server and any possible platform interacting through a corba bus for getting data configuration, synchronisation and data archiving.

Software Architecture for Processing Clusters Based on I2O

Mainstream computing equipment and the advent of affordable multi-Gigabit communication technology permit us to address data acquisition and processing problems with clusters of COTS machinery. Such networks typically contain heterogeneous platforms, real-time partitions and even custom devices. Vital overall system requirements are high efficiency and flexibility. In preceding projects we experienced the difficulties to meet both requirements at once. Intelligent I/O (I2O) is an industry specification that defines a uniform messaging format and execution environment for hardware and operating system independent device drivers in systems with processor based communication equipment. Mapping this concept to a distributed computing environment and encapsulating the details of the specification into an application-programming framework allow us to provide architectural support for (i) efficient and (ii) extensible cluster operation. This paper portrays our view of applying I2O to high-performance clusters. We demonstrate the feasibility of this approach and report on the efficiency of our XDAQ software framework for distributed data acquisition systems.

Overview of ECE diagnostics on LHD

An electron cyclotron emission (ECE) diagnostic system has been installed on the large helical device (LHD). In LHD, the magnetic field profile has a peak near the plasma center, so the electron temperature profile of both sides can be continuously measured by the ECE system using two antennas. The ECE spectrometers are as follows, two heterodyne radiometers with the local frequency of 70 and 132 GHz, respectively, a grating polychromator and a Michelson spectrometer. The measurements are processed by the distributed data acquisition system. The angle of the magnetic field from the toroidal direction varies from −30 to +30° in LHD. It is found that the polarization of ECE follows the angle of the magnetic field when the electron density is high enough. The effect of the polarization is considered when the temperature calibration is performed. ECE is useful to distinguish small perturbations in the electron temperature profile, for example, to effects of a local island diverter.

Data acquisition systems at Fermilab

Experiments at Fermilab require an ongoing program of development for high speed, distributed data acquisition systems. The physics program at the lab has recently started the operation of a Fixed Target run in which experiments are running the DART data acquisition system. The CDF and DO experiments are preparing for the start of the next Collider run in mid 2000. Each will read out on the order of 1 million detector channels. In parallel, future experiments such as BTeV R&D and Mines have already started prototype and test beam work. BTeV in particular has challenging data acquisition system requirements with an input rate of 1500 Gbytes/sec into level 1 buffers and a logging rate of 200 Mbytes/sec. This paper will present a general overview of these data acquisition systems on three fronts-those currently in use, those to be deployed for the Collider Run in 2000, and those proposed for future experiments. It will primarily focus on the CDF and D0 architectures and tools.