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    User name saw, gayou

    Log entry time 21:46:40 on January 8,2005

    Entry number 138594

    keyword=ROC5/6 readout list changes

    Several changes have been made to the readout lists for the BigBite and neutron bars. Starting with Run 1550, the following changes have been made.

    1. ROC5: A "0xfabc" set of words has been added to the end of the event. These words are:

    0xfabc0005
    icnt (Event counter modulo 20000)
    iimax (The maximum # times that any VME module had to be probed for data
    datascan (Bit pattern of which modules had data. Bits 0-9)
    time1 (The vxworks clock variable vxTicks)
    event_ty (The coda event type)
    0xfaaa0001

    2. ROC5: A word indicating whether the run was in buffered mode or not is written to the event. 0xfabb0000 if not buffered mode, 0xfafbbf00 if in buffered mode but not a sync event, and 0xfafbbf01 if in buffered mode and a sync event.

    3. ROC5: After reading the modules, the readout list checks for syncronization. This is the usual sync logic. If in unbuffered mode, this sync check (make sure all modules have no data) is performed for every event. For buffered mode, the sync check is performed only for sync events. The usual 0xdcfe words are placed in the event in the event of any sync errors. The "slot" in the 0xdcfe word is the module number from 0-9 in the order that they are readout.

    4. ROC6: The fastbus ROC already has the sync logic. Two words were added to the 0xfabc data, time1 (vxTicks) and the event type.

    Starting with run 1555 the programming of the BigBite VME modules was changed. Previously, the modules were programmed to indicate no event if a gate was received, but no hits were recorded (either because they were below threshold for ADCs or out of time for TDCs). This has been changed so that if the module receives a gate, but no hits, it will still register as having an event.

    What this means for the data in the event is that 0xbad0adcN and 0xbad0ddcN words truly indicate something bad rather than just a module without any hits. It would probably be good to note such words in the analyzer.

    (This change is effected by setting bit 12 in the bitset2 register for the V792 and V775 modules.)