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Raw Data Format in the DAQ

Raw Data Format in the DAQ. Franco CARENA CERN PH-AID ALICE Offline October 2006. Raw data formatting in the DAQ. CTP. Event Fragment over DDL (CDH + Raw Data). LTU. LTU. TTC. TTC. Event Fragment in LDC (Eq Header + CDH + Raw Data). FERO. FERO. FERO. FERO. DDL.

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Raw Data Format in the DAQ

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  1. Raw Data Formatin the DAQ Franco CARENA CERN PH-AID ALICE Offline October 2006

  2. Raw data formatting in the DAQ CTP Event Fragment over DDL(CDH + Raw Data) LTU LTU TTC TTC Event Fragment in LDC(Eq Header + CDH + Raw Data) FERO FERO FERO FERO DDL Sub-event to network or to disk (Header + 1 or several event fragments) DDL LDC LDC Event (Header + 1 or several sub-events) Event Building Network GDC GDC Data file (DATE or ROOT format) ALICE Standard data format is ROOT ! DATE V5

  3. Event Logic Structure Event Base Header (Header extension) Sub-event Sub-event Base Header Sub-event (Header extension) Event fragment Equipment Header Sub-event Event Fragment Common Data Header Raw data Equipment Header Sub-event Event Fragment DDL LDC GDC DATE V5

  4. Common Data Header The Common Data Header (CDH) needs to be generated by the detector electronics together with the Trigger System and transmitted over the DDL (first 8 words of each fragment). “Data Format over the ALICE DDL”, ALICE-INT-2002-010 V10.0 31 24 16 8 0 CDH Format 0 Block Length Version = 2 ! 1 Version 0 L1 Trigger Message 0 Bunch Crossing 2 0 Orbit Number Mandatory Optional Must be zero 3 Block Attributes Participating Sub-Detectors 4 0 Status&Error Bits Mini Event ID 5 Trigger Classes Low 6 ROI Low 0 Trigger Classes High 7 ROI High DATE V5

  5. equipment size equipment type DetectorIdentifier DDL Index Equipment Header (28 bytes) equipment header + fragment size equipment type (RORC) equipment id +0 +4 +8 equipment id type attribute +12 +24 basic element size DATE V5

  6. DDL Index (Detector Dep.) DDL Links identifiers (Side A) DATE V5

  7. event size event header size event type event LDC id event magic event version event run number event GDC id LDC/GDC Header +0 total size in bytes 68 bytes + extension period + orbit + bunch crossing derived from the L2a message derived from the L2a message flags time() +4 +8 +12 +16 +20 event id +24 event trigger pattern +32 +40 event detectors pattern type attribute +44 +56 +60 +64 eventTimestamp DATE V5

  8. Event Format GDC with 2x LDCs GDC event header LDC event header Equipment header Event Fragment LDC Equipment header Offline recommends to record data with GDC format even if there is only 1 LDC ! “pointers” Event Fragment LDC event header Equipment header LDC Event Fragment DATE V5

  9. Format Selection in DAQ Switch on event-building in order to have data formatted with GDC format Switch on recording on PDS in order to start the recording program in ROOT format. DATE V5

  10. Format Selection in ECS Switch on event-building in order to have data formatted with GDC format Switch on recording on PDS in order to start the recording program in ROOT format. DATE V5

  11. Conclusion • Everything is crystal clear ! • References: - “Data Format over the ALICE DDL”, ALICE-INT-2002-010 V10.0 - ALICE DAQ and ECS User’s Guide, ALICE-INT-2005-015 - Identification of DDL links in ALICE data, ALICE-INT-2006-??? DATE V5

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