Use of ROOM in the design of data-acquisition software components

Presentation made at the Real Time Conference, Santa Fe, New Mexico 14-18 June 1999The Event Builder and Distribution System (EBDS) is a component of the data-acquisition architecture of the ALICE experiment at CERN. The purpose of the EBDS is to dispatch the sub-events originated in the detector front-end electronics to the processors of the Event Filter Farm, where the full events are assembled.For the design of the EBDS, we use the Real-time Object-Oriented Modelling method (ROOM), which was chosen because of its powerful modelling paradigm, well suited to this type of application. The use of ROOM is aided by the ObecTime Developer tool set, which fully supports the method and covers all the aspects of the development cycle, from analysis to code generation. Fast prototyping and simulation bring a new perspective to the designer, who can advance by gradual refinements.We describe how ROOM has been used to design a model of both the EBDS and its environment, and the results obtained from the simulation. We also review the experience acquired with ROOM and the ObjecTime tool, and indicate what benefits and obstacles we encountered.<P

Online Performance Monitoring of the Third ALICE Data Challenge (ADC III)

The ALICE data acquisition system has been designed for a maximum bandwidth of 2.5 GB/s for event building and of 1.25 GB/s for mass storage. In order to attain a gradual integration of the overall computing infrastructure, the present hardware components and software prototypes are tested during regular ALICE data challenges. The third one (ADC III) took place from January to March 2001 as a joint effort between the ALICE online/offine team and the CERN IT division. The main goal of this data challenge was to achieve a stable 300 MB/s throughput in the event building network and a 100 MB/s throughput to CASTOR over periods of a few days. Performance monitoring was another goal of this exercise, where a prototype (dateStat ) was developed to collect and display statistics. In this paper we will introduce this online monitoring system and report on some of the obtained results. It is structured in three parts: (1) An overview will be given on the testbed hardware, the software running on it, and the data flow. (2) The architecture of the monitoring system will be described, which consists of a set of C programs, Perl/gnuplot/CGI scripts ,and a MySQL database. It allows to measure individual/aggregate data rates,collected data volumes, and CPU loads. All these values can be visualized on web pages both on a run-by-run and global basis. (3) Various plots will be shown to illustrate the usefulness of this online monitoring system and to document the outcome of the ADC III. Finally, some ideas will be pointed out how to advance dateStat

The Usage of ROOT for Online Monitoring in the ALICE DATE System

Presentation for CHEP2000Data Acquisition systems for HEP applications need constant monitoring (online and offline) of their data streams to accomplish several tasks: quality checking, tuning, statistics, pre-analysis. Monitoring tasks can and should use the same tools as data analysis products (conventions, libraries, environments) to reduce training, installation, development and support efforts and -at the same time - to strengthen the liaison between the online and the offline worlds. The ALICE DATE Data Acquisition system available today for R&D and for test beams is fully integrated with the ROOT environment. A simple DAQ-oriented approach and a more complex OO-based model have been developed to allow a variety of programming paradigms and to validate the complete life cycle of monitoring tools, both for online and offline environments

PCI Based Read-out Receiver Card in the ALICE DAQ System

The Detector Data Link (DDL) is the high-speed optical link for the ALICE experiment. This link shall transfer the data coming from the detectors at 100 MB/s rate. The main components of the link have been developed: the destination Interface Unit (DIU), the Source Interface Unit (SIU) and the Read-out Receiver Card (RORC). The first RORC version is based on the VME bus. The performance tests show that the maximum VME bandwidth could be reached. Meanwhile the PCI bus became very popular and is used in many platforms. The development of a PCI-based version has been started. The document describes the prototype version in three sections. An overview explains the main purpose of the card: to provide an interface between the DDL and the PCI bus. Acting as a 32bit/33MHz PCI master the card is able to write or read directly to or from the system memory from or to the DDL, respectively. Beside these functions the card can also be used as an autonomous data generator. The card has been designed to be well adapted to applications, which require small software overhead such the high-speed data acquisition systems. The implementation of the firmware will be presented. For the logic design we are using VHDL and schematic draw. Software library routines were written in C and are available on Linux OS. The results of performance measurements will be available to allow the comparison between the VME-RORC and PCI-RORC. In the conclusion the future plans and the idea of the improved (64bit/66MHz) PCI-RORC will be shown

Radiation Tolerance Qualification Tests of the Final Source Interface Unit for the ALICE Experiment

The ALICE Detector Data Link (DDL) is a high-speed optical link designed to interface the readout electronics of ALICE sub-detectors to the DAQ computers. The Source Interface Unit (SIU) of the DDL will operate in radiation environment. Previous tests showed that a configuration loss of SRAM-based FPGA devices may happen and the frequency of undetected data errors in the FPGA user memory area is also not acceptable. Therefore, we redesigned the SIU card using another FPGA based on flash technology. In order to detect bit errors in the user memory we added parity check logic to the design. The new SIU has been extensively tested using neutron and proton irradiation to verify its radiation tolerance. In this paper we summarize the design changes, introduce the final design, and the results of the radiation tolerance measurements on the final card

Review and prospects of the CASCADE data acquisition system at CERN

CASCADE, a multi-processor real-time data-acquisition system for HEP experiments developed at CERN by the ECP-DS group, has now been in operation for one year. The current implementation supports configurations based on VMEbus processors running OS-9 and on UNIX workstations interconnected via VICbus or Ethernet. The project is reviewed by describing the main characteristics of the package, the applications in which it has been used, and the results of this experience. The main improvements of 1994, which include a parameterized multi-level event builder, a remote monitoring option and a powerful run control facility, as well as ongoing developments and prospects for 1995, are presented