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Summary: A 33kHz beam train simulation (28 buckets between shots) with a starting gap of 14000 buckets to allow a periodic 1Hz Andor to readout while not receiving beam.  A 100Hz trigger is added for other non-integrating detectors (e.g. opals).  Each sequence is repeated twice, although there appears to be an "off by one" difference in the definition of the repeat count of traingenerator (repeat=2) and periodicgenerator (repeat=1).  The "--notify" flag on periodic generator tells the DAQ to end the scan step after that finite sequence is complete after 2 andor images.  The andor "shutter" is always open, so the trigger event-code only starts the readout, not the exposure.  The first andor readout-trigger in the first step clears out old charge at the beginning so the very first image data is "corrupted".  Note that 14000+32000*28=910000 (14000 is starting gap for andor readout, and 32000 shots 28 buckets apart adds up to the 910000 buckets that the accelerator always repeats on every 0.98 seconds).  The number of beam shots is set to 32001 instead of 32000 because without this there would be no high-rate beam shot at the same time as the andor trigger (this can be seen with seqbrowser.py): there is a requirement in the DAQ that the highest rate trigger must show up in every event, except for rare cases of deadtime.

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