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Data Format for CKM

Data Format for CKM. J. Wu, S. Hansen, M. Bowden, B. Haynes, P. Cooper For CKM Collaboration. Questions. (1) How data are generated? Undefined but some knowledge exists. (2) What’s impact after data streams flow through the event builder (switch)? Unknown but there are some guesses.

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Data Format for CKM

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  1. Data Format for CKM J. Wu, S. Hansen, M. Bowden, B. Haynes, P. Cooper For CKM Collaboration

  2. Questions • (1) How data are generated? • Undefined but some knowledge exists. • (2) What’s impact after data streams flow through the event builder (switch)? • Unknown but there are some guesses. • (3) What are the requirements of the PC farm processors? • Unknown.

  3. Challenge • Today’s TDC or ADC pumps out one digital number per CLK cycle. • Only the outputs with hit will be sent to DAQ. (Zero suppression). • CLK cycle information will be destroyed during zero suppression. • Time stamp (TS) must be attached to TDC or ADC data by designers.

  4. 9 ns 09 02 03 04 05 06 07 08 09 Example: TDC CLK In TDC TS (8bits) • Channel is hit 9 ns after leading edge of the CLK. • At which CLK cycle? • At CLK cycle 05. • At 0005 or 1F05? or 2005? or 2105? … ? (Y2K again) • That is a challenge. • Using 16 or 32 bit TS? Not a solution.

  5. TS Counter Roll-over: Problem It’s hard to know in which century these events happened 17 86: Morzart wrote “Le nozze di Figaro”. ?? 24: Beethoven wrote Symphony no. 9. ?? 05: Einstein bought a new hat. ?? 95: Windows 95 went to market. Consider this chronicle record ?? 08: LHC went to operation. ?? 13: Fish became smarter than human being.

  6. TS Counter Roll-over: Solution Century of the dummy records can be identified 17 86: Morzart wrote “Le nozze di Figaro”. 18 00: Nothing important happened. 18 24: Beethoven wrote Symphony no. 9. 19 00: Nothing important happened. 19 05: Einstein bought a new hat. 19 95: Windows 95 went to market. 20 00: Nothing important happened. 20 08: LHC went to operation. Insert dummy records… 21 00: Nothing important happened. 22 00: Nothing important happened. Century of the events can also be identified 23 13: Fish became smarter than human being.

  7. The solution is: • Inserting a dummy record (roll-over marker) whenever the TS roll-over happens. • There is no step 2.

  8. DAQ System Model

  9. TS Establishment TS10 Digitizer Reset/Sync. CLK CLK Sys. No-op DATA Receiver Serial Links, Optic fiber or LVDS pairs TS32 PC Farm Event Builder (Switch)

  10. Hit Data Package “Triggerless” scheme: Use hit as guide. Roll-over marker is inserted whenever counter roll-over, regardless there are hits or not in between. Digitizer Roll-over marker is inserted. TS of hit is attached with hit data. CLK Sys. Roll-over marker is inserted at beginning. DATA Receiver PC Farm Event Builder (Switch)

  11. Data Transmit format Digitizer More data and idle CLK Sys. Emergency service request Send hit data blocks when they are ready. Emergency requests are serviced by CLK sys. and commands are sent back. DATA Receiver When there is nothing else to transmit, send No-op and TS to maintain TS counters. PC Farm Event Builder (Switch) DAQ data flow

  12. Two Types of Digitizers for CKM • TDC only channels: (chamber, RICH) • ADC+TDC channels: (veto systems)

  13. Example: Chambers: (TDC only) Roll-over marker at later time 02 01 1 Channel etc. TS of roll-over 2 00 TDC 0 TDC TS of Hit 1 FF FE 01 1 00 1 Channel etc. TS of roll-over 0 FF Roll-over marker FE 05 TDC 0 TDC TS of Hit 04 03 02 TDC 0 TDC TS of Hit 01 0 00 1 Channel etc. TS of roll-over 3 FF Roll-over marker Disabled 256 CLK cycles after reset FE

  14. 15 8 7 0 Example: Chambers: (data bitmap) Roll-over Marker 1 Ch. # TS (10 bit) TDC data 0 E TDC (6 bit) TS (8 bit) D Time (1ns/bin) Earliest Time from CLK leading edge Double hit marker

  15. Why Transmit 8 bits TS? • Convenient • Less data volume

  16. Example: g Veto (ADC+TDC data) 5 MeV hit E(MeV)= 3 1.5 0.5 Range 2bits Roll-over Marker 14 bits FADC 6bits 0 0 0 0 0 0 0 0 0 12 6 2 0 0 M H Header 14bits T TDC 6bits Hitlet

  17. 15 8 7 0 Example: g Veto (data bitmap) Roll-over Marker 1 1 E Ch. # TS (10 bit) Hitlet Header 1 0 E TS (10 bit) 0 0 QIE (TS1) QIE (TS0) QIE data 0 0 QIE (TS1’) QIE (TS2) TDC data 0 1 TDC (6 bit) TS (8 bit) 0 0 0 0 0 0 0 0 0 12 6 2 0 0 M H T

  18. From Digitizer to Data Receiver Digitizer Side ch1 chN ch0 Millenary (=256 Centenaries?) Hit data Centenary (=256 CLK cycles) Additional header with Centenary count ch0 ch1 chN TS roll-over marker Data Receiver Side

  19. Data Receiver Side Pass Through Switch ch0 ch1 chN Inside PC Farm The “only” requirement is: a Millenary must stay together. chN Data of same Millenary # from different channels are sent to same PC farm node. ch0 It’s OK in wrong channel order. ch1

  20. To Do • A lot of works must be done. • Better understanding on going through switch is needed.

  21. The End Thanks

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