>
> > I'm not sure what Chris means by "digitizing during a stop."
> > Possible the same cause for both problems? If these do not
> > represent much of the data, maybe the fix can be replaced by
> > something which tosses out the events... I would have to know a
> > little more about what "digitizing during a stop" meant, though.
> >
>
> OK, I'll explain this. I wasn't sure if everyone knew about this or
> not.
>
> First off, let's look at the data from the beginning of this event:
>
> Chan: 3090000
> VME WFD Node
> Channel: 3090000
> Tics to data: 0
> Number of buckets: 2172
> Time Timewd dBits AD0 AD1 AD2 AD3
> 0 61198 8888 28 28 27 32 -1.4 -1.4 -0.6 -4.6
> 327690 61196 8888 31 35 33 32 -3.8 -7.0 -5.4 -4.6
> 327710 61192 8888 32 29 33 35 -4.6 -2.2 -5.4 -7.0
> 327730 61188 8800 37 34 30 27 -8.7 -6.2 -3.0 -0.6
>
> OK now look at the time words. You see the first one goes from 61198
> to 61196. This isn't really supposed to happen. Time Words are
> always supposed to be separated by 4. This one is only separated by
> 2. Now what happens if you use these words to expand the time into an
Isn't this exactly what you would expect if the Stop Enable bit (bit 6)
of the control register is turned on? When this bit is enabled, the last
data in the RAM contains the stop time rather than the last sample time:
so the difference between the last two timewords could be 1 to 4. I think
this bit is set in the control register, so I am surprised why this kind
of thing happens so infrequently.
Concerning the missed rollovers, is the Rollover Enable bit (bit 4) in the
control register being set? Since this forces a sample storage cycle when
the timeword rolls over, it should provide an additional handle to
detect a rollover apart from an increment in the timeword.
- Ash