L. Tremblet

The ROD Crate DAQ of the ATLAS data acquisition system

In the ATLAS experiment at the LHC, the ROD Crate DAQ provides a complete framework to implement data acquisition functionality at the boundary between the detector specific electronics and the common part of the data acquisition system. Based on a plugin mechanism, it allows selecting and using common services (like data output and data monitoring channels) and developing simple libraries to control, monitor, acquire and/or emulate detector specific electronics. Providing also event building functionality, the ROD Crate DAQ is intended to be the main data acquisition tool for the first phase of detector commissioning. This paper presents the design, functionality and performance of the ROD Crate DAQ and its usage in the ATLAS DAQ and during detector tests

The base-line DataFlow system of the ATLAS trigger and DAQ

The base-line design and implementation of the ATLAS DAQ DataFlow system is described. The main components of the DataFlow system, their interactions, bandwidths, and rates are discussed and performance measurements on a 10% scale prototype for the final ATLAS TDAQ DataFlow system are presented. This prototype is a combination of custom design components and of multithreaded software applications implemented in C++ and running in a Linux environment on commercially available PCs interconnected by a fully switched gigabit Ethernet network.

The ATLAS DAQ and event filter prototype “−1” project

Abstract A project has been approved by the ATLAS Collaboration for the design and implementation of a Data Acquisition and Event Filter prototype, based on the functional architecture described in the ATLAS Technical Proposal. The prototype consists of a full “vertical” slice of the ATLAS Data Acquisition and Event Filter architecture, including all the hardware and software elements of the data flow, its control and monitoring as well as all the elements of a complete on-line system. This paper outlines the project, its goals, structure, schedule and current status and describes details of the system architecture and its components.

Performance of the final Event Builder for the ATLAS Experiment

Event data from proton-proton collisions at the LHC will be selected by the ATLAS experiment in a three level trigger system, which reduces the initial bunch crossing rate of 40 MHz at its first two trigger levels (LVL1+LVL2) to ~3 kHz. At this rate the Event-Builder collects the data from all read-out system PCs (ROSs) and provides fully assembled events to the the event-filter (EF), which is the third level trigger, to achieve a further rate reduction to ~ 200 Hz for permanent storage. The event-builder is based on a farm of O(100) PCs, interconnected via gigabit Ethernet to O(150) ROSs. These PCs run Linux and multi-threaded software applications implemented in C++. All the ROSs and one third of the event-builder PCs are already installed and commissioned. We report on performance tests on this initial system, which show promising results to reach the final data throughput required for the ATLAS experiment.

The ATLAS ROBIN

The ATLAS readout subsystem is the main interface between ~ 1600 detector front-end readout links and the higher-level trigger farms. To handle the high event rate (up to 100 kHz) and bandwidth (up to 160 MB/s per link) the readout PCs are equipped with four ROBIN (readout buffer input) cards. Each ROBIN attaches to three optical links, provides local event buffering for approximately 300 ms and communicates with the higher-level trigger system for data and delete requests. According to the ATLAS baseline architecture this communication runs via the PCI bus of the host PC. In addition, each ROBIN provides a private Gigabit Ethernet port which can be used for the same purpose. Operational monitoring is performed via PCI. This paper presents a summary of the ROBIN hardware and software together with measurements results obtained from various test setups.

The ROD crate DAQ software framework of the ATLAS data acquisition system

In the ATLAS experiment at the LHC, the ROD Crate DAQ provides a complete software framework to implement data acquisition functionality at the boundary between the detector specific electronics and the common part of the data acquisition system. Based on a plugin mechanism, it allows selecting and using common services (like data output and data monitoring channels) and developing software to control and acquire data from detector specific modules providing the infrastructure for control, monitoring and calibration. Including also event building functionality, the ROD Crate DAQ is intended to be the main data acquisition tool for the first phase of detector commissioning. This paper presents the design, functionality and performance of the ROD Crate DAQ and its usage in the ATLAS data acquisition system and during detector tests.

Deployment and use of the ATLAS DAQ in the combined test beam

The ATLAS collaboration at CERN operated a combined test beam (CTB) from May until November 2004. The prototype of ATLAS data acquisition system (DAQ) was used to integrate other subsystems into a common CTB setup. Data were collected synchronously from all the ATLAS detectors, which represented nine different detector technologies. Electronics and software of the first level trigger were used to trigger the setup. Event selection algorithms of the high level trigger were integrated with the system and were tested with real detector data. A possibility to operate a remote event filter farm synchronized with ATLAS TDAQ was also tested. Event data, as well as detectors conditions data were made available for offline analysis

The C-RORC PCIe card and its application in the ALICE and ATLAS experiments

The ALICE and ATLAS DAQ systems read out detector data via point-to-point serial links into custom hardware modules, the ALICE RORC and ATLAS ROBIN. To meet the increase in operational requirements both experiments are replacing their respective modules with a new common module, the C-RORC. This card, developed by ALICE, implements a PCIe Gen 2 x8 interface and interfaces to twelve optical links via three QSFP transceivers. This paper presents the design of the C-RORC, its performance and its application in the ALICE and ATLAS experiments.

PLLS, a Portable Interactive Language System

PILS (a Portable Interactive Language System) has been designed and implemented at CERN to improve the portability of interactive programs used in the electronics test environment. The syntax of PILS is discussed, with emphasis on the features which distinguish PILS from some other interactive languages, such as data types, modules, control structures, full subroutines and functions with parameters, access to external (normally FORTRAN) libraries. The fact that PILS is written in PASCAL and has been designed for easy transportability is emphasised. PILS is a language SYSTEM which means that the command and editing interfaces are identical on all implementations. The status of PILS on various computer systems is discussed, and remarks are made on the status of the first PILS compiler (for VAX/VMS and VAX/UNIX) and on plans for future PILS versions. A particular implementation of PILS on a small CERN test system is briefly described.

The ATLAS Event Builder

Event data from proton-proton collisions at the LHC will be selected by the ATLAS experiment in a three-level trigger system, which, at its first two trigger levels (LVL1+LVL2), reduces the initial bunch crossing rate of 40 MHz to ~3 kHz. At this rate, the Event Builder collects the data from the readout system PCs (ROSs) and provides fully assembled events to the Event Filter (EF). The EF is the third trigger level and its aim is to achieve a further rate reduction to ~200 Hz on the permanent storage. The Event Builder is based on a farm of 0(100) PCs, interconnected via a Gigabit Ethernet to 0(150) ROSs. These PCs run Linux and multi-threaded software applications implemented in C++. All the ROSs, and substantial fractions of the Event Builder and Event Filter PCs have been installed and commissioned. We report on performance tests on this initial system, which is capable of going beyond the required data rates and bandwidths for Event Building for the ATLAS experiment.