Instead of a general pre-meeting on the status of the waveform system, I
would like to organize a meeting that will concentrate on readout and
data handling issues. I still welcome separate talks on wfd work, but
suggest you try to get them into the general meeting. If you have a 1-2
transparency presentation that would not call for a separate talk, I
would be happy to show them during my system report on your behalf.
As for the readout meeting, I have several topics which I suggest we
talk about. I am most interested in getting some technical guidance from
the Italian DAQ experts on our options for handling large events.
Let me remind you of the situation:
* A single tank (2 wfd channels) will amount to about 10 kB of data.
* We must allow for occasional events with many channels.
* There is currently a buffer size restriction of 65000 bytes.
* The readout speed using KAV30 + VIC8250 is about 0.5 MB/sec.
* The readout speed using a 68040 in-crate is not much faster: 0.8 MB/s.
In the current system, we have a daisy chain of two WFD crates on the
VICbus connected to a uVaX. This works. But it has the buffer size
problem, and is generally slow (no parallel operation). Also, the
VIC8250 is rather obsolete- however, it is still very expensive.
I am interested in an alternative architecture that can execute code
on both wfd crates in parallel. The most important criterion is that
it integrate easily with the current data stream. By the way, it is
hard to imagine having enough money for both VICbus and separate
processors. Therefore, another means of connecting is called for,
such as DECNET or sockets on Ethernet.
OK, solving the buffer size issue, I believe is the most important
item on the agenda. Here is a list of other topics for discussion.
1) selective channel readout strategies
2) rate limiting- protection against hot triggers
3) trigger rates (non-hot) and data size
4) offline data handling: what do we archive? what do we distribute?
And of course any topics you might think of that I have forgotten.
If you have any questions, please contact me.
I will leave the scheduling of this meeting to the Rome organizers.
Watch the agenda for more information.