You are here: Foswiki>Timing Web>WebHome (17 Sep 2019, DietrichBeck)Edit Attach

General Machine Timing System at GSI and FAIR

whiterabbit logo.png

The FAIR facility involves a long chain of accelerators which need to be tightly synchronized. This is achieved by the General Machine Timing (GMT) system, a distributed event generation system based on the notion of time. Time synchronization is achieved by using White Rabbit (WR), a fully deterministic Ethernet-based field bus for clock transfer and synchronization. The key components of the GMT are a so-called Data Master (DM) that schedules actions by broadcasting messages, a WR network and Timing Receiver (TR) nodes executing machine relevant actions on time.

The primary tasks of the timing system are the following.
  • Time-Synchronization of ~2000 - 3000 nodes with sub-ns accuracy over fiber lengths of up to 2 km.
  • Distribution of TAI counters with ns accuracy.
  • Generation of timing events for synchronization of equipment.


The aim of this timing web is to provide an overview on the timing system and its relationship to other systems. Moreover, it is the central point for documentation. Please note, that the timing system is still under development.



Scheduled downtime of the GMT production system as agreed with operations

GMT-schedule 2017-10-12.jpg
Figure: Schedule for the next weeks based on shutdown planning. For an overview, click here.


  • 17-Sep-2019: maintenance timing system ends (informative: LSA & BSS updates ongoing probably till the evening)
  • 16-Sep-2019: maintenance timing system starts
  • 11-Sep-2019: Enigma release 5.0.2
    • minor update
    • no further release(s) planned until the start of the beam time
    • the timing team recommends migration of frontends to this release
  • 09-Sep-2019: power-cut in parts of the facility
    • clock master, data master, management master and WR network survived thx to UPS
    • some services like the timing test facility remained down and needed to be restarted manually
  • 09-Sep-2019: ion source operation @ CRYRING starts
  • 27-Aug-2019: maintenance timing system ends; finally PROduction is up again
  • 23-Aug-2019: need to extend maintenance window; we apologize for the inconvenience
  • 20-Aug-2019: maintenance timing system starts
  • 19-Aug-2019: Enigma released!
  • 08-Jul-2019: job opportunity in our team
  • 28-Jun-2019: maintenance timing system ends
  • 24-Jun-2019: maintenance timing system starts
  • 16-Apr-2019: beam operation ends
  • 01-Apr-2019: contract signed for the delivery of White Rabbit Switches for FAIR
  • 19-Mar-2019: technical stop: DM update (hardened against 'self-flushing of queues')
  • 08-Mar-2019: technical stop: DM update (stricter testing of schedules/cmds)
  • 12-Feb-2019: technical stop: DM update (added software reset)
  • 05-Feb-2019: beam operation starts
  • 01-Feb-2019: ready for beam operation (see here)
  • 25-Jan-2019: job opportunity in our team

GSI Timing Team

-- DietrichBeck - 17 Sep 2019
Topic attachments
I Attachment Action Size Date Who Comment
GMT-schedule_2017-10-12.jpgjpg GMT-schedule_2017-10-12.jpg manage 105 K 10 Sep 2019 - 05:55 DietrichBeck plan for the next weeks....
Topic revision: r265 - 17 Sep 2019, DietrichBeck
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback