Author: Kreider, M.
Paper Title Page
TUCPL06 Verification of the FAIR Control System Using Deterministic Network Calculus 238
 
  • M. Schütze, S. Bondorf
    DISCO, Kaiserslautern, Germany
  • M. Kreider
    GSI, Darmstadt, Germany
  • M. Kreider
    Glyndŵr University, Wrexham, United Kingdom
 
  Funding: Carl Zeiss Foundation
The FAIR control system (CS) is an alarm-based design and employs White Rabbit time synchronization over a GbE network to issue commands executed accurate to 1 ns. In such a network based CS, graphs of possible machine command sequences are specified in advance by physics frameworks. The actual traffic pattern, however, is determined at runtime, depending on interlocks and beam requests from experiments and accelerators. In 'unlucky' combinations, large packet bursts can delay commands beyond their deadline, potentially causing emergency shutdowns. Thus, prior verification if any possible combination of given command sequences can be delivered on time is vital to guarantee deterministic behavior of the CS. Deterministic network calculus (DNC) can derive upper bounds on message delivery latencies. This paper presents an approach for calculating worst-case descriptors of runtime traffic patterns. These so-called arrival curves are deduced from specified partial traffic sequences and are used to calculate end-to-end traffic properties. With the arrival curves and a DNC model of the FAIR CS network, a worst-case latency for specific packet flows or the whole CS can be obtained.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICALEPCS2017-TUCPL06  
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TUPHA092 Two Years of FAIR General Machine Timing - Experiences and Improvements 633
 
  • M. Kreider, R. Bär, D. Beck, A. Hahn, N. Kurz, C. Prados, S. Rauch, M. Reese, M. Zweig
    GSI, Darmstadt, Germany
  • M. Kreider
    Glyndŵr University, Wrexham, United Kingdom
 
  The FAIR General Machine Timing system has been in operation at GSI since 2015 and significant progress has been made in the last two years. The CRYRING accelerator was the first machine on campus operated with the new timing system and serves as a proving ground for new control system technology to this day. A White Rabbit (WR) network was set up, connecting parts of the existing facility. The Data Master was put under control of the LSA physics core. It was enhanced with a powerful schedule language and extensive research for delay bound analysis with network calculus was undertaken. Several form factors of Timing Receivers were improved, their hard and software now being in their second release and subject to a continuous series of automated long- and short-term tests in varying network scenarios. The final goal is time-synchronization of 2000-3000 nodes using the WR Precision-Time-Protocol distribution of TAI time stamps and synchronized command and control of FAIR equipment. Promising test results for scalability and accuracy were obtained when moving from temporary small lab setups to CRYRING's control system with more than 30 nodes connected over 3 layers of WR Switches.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-ICALEPCS2017-TUPHA092  
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