[Olympus] SlowControl

[Jan Bernauer]

Dear colleagues,

 in Mainz, the slow control saves everything (event driven) in its own
database, but at the start of a run, the complete status quo is dumped
into the data acquisition file. That is about 1 to 3 MB of data, so no
problem. It is so much easier to analyse your data if you have
everything consistent in a single location, and you don't have to match
and mix.

We even mix important slow control information into the readout event
stream, like target parameters (pressure, temperature), event scalers
etc. Of course not for every event, but on every change of these values.
That proved *very* useful.

Redundancy in the data saved my analysis several times. I suggest we
store the start and stop of each run in the slow control log, and for
every event as much timing info as possible (run time, live time, dead
time from scalers, unix time). Do we have a plan for the luminosity and
dead time estimation?

Best regards,
Jan

Alexander Winnebeck wrote:

> @ John: I wonder if you mix up two things here. There is the slowcontrol 
> and the online monitoring. The slowcontrol will control the HVs, 
> temperatures, flows, machine parameters etc. and the online monitoring 
> will evaluate the incoming data from the detectors, i.e. showing TDC and 
> ADC spectra, count rates, hit distributions etc.
> To have an offline matching of sc data and the data of the detectors, we 
> might have a table in the sc with the time of begin and end of run with 
> the run number, or the unix time is stored in every event in the data 
> stream.
> 


-- 
Jan C. Bernauer                       email: bernauer at kph.uni-mainz.de
Institut für Kernphysik               tel  : 06131 - 39 25826
Johannes-Gutenberg-Universität Mainz  fax  : 06131 - 39 22964
Johann-Joachim-Becher-Weg 45
55099 Mainz