July 2003
Why not read the Data Acquisition at TUDA
user guide? If you just cannot manage that at least read these selections.
The raw data received
from the VME electronics is processed in the data acquisition processor (tudavme)
and reformatted using the standard MIDAS data format (see http://npg.dl.ac.uk/documents/edoc073/edoc073.html)
before writing to tape. Sortshell has an event handler which can accept this
data. You should find that Sortshell
reports zero errors when processing this data.
Login to tuda0
and start Sortshell in the usual way.
In order to
run Sortshell in online mode data must be transferred from the data acquisition
system (tudavme) to the tape server which must be in the GO state.
To get data for Sortshell – start the experiment writing to tape OR if tape output is not required then while in STOP state go to the Tape Control window and select No Storage. Then GO.
Remember to disable No Storage when you are ready to write data to
tape.
Use only the MIDAS
Data Acquisition Experiment Control (TUDA) window. To SETUP the data acquisition system
(for example after restart the VME) click on the big yellow SETUP button
and select the option Setup everything.
Ensure that Tape
Server Enabled and TS Transfer Enabled are selected. Use the green GO button to start data
acquisition and the red STOP button to halt.
A visual check of the VME hardware.
S9418 ADC modules.
DTACK (top green LED) - when on module is being accessed (normally for data readout)
OFFLINE (red led) - when on data acquisition is STOPPED and off when data acquisition is GOING
MDTRG - trigger is being processed
GLINH - global inhibit - adc is busy - normally processing a trigger
If you get no DTACK then no data is being read out. However if GLINH is off and there is no MDTRG then you are not sending in triggers.
V767 TD modules
DTACK - as for the S9418 but seem to be faulty
DRDY - when on the module has data - this should normally be a dull yellow when running because the data acquisition program reads the data out as it arrives. If a bright solid yellow but the S9418 modules are reading normally then the V767 has processed more triggers than the S9418. Your data will not be correlated. Try a STOP and GO. If the problem repeats check the trigger into the V767 which is derived from the S9418 COM signal.
By default the histogramming option is ALL. A
(4K channel) histogram is created for each S9418 adc channel. A (2K channel) histogram
is created for tdc channels 1 => 127 for each V767 module.
Additionally 2 histograms (Stat & Rate)
are created which show the activity on a data item basis.
The Rate histogram shows the increment
rate / sec for the Stat histogram and so is a very useful check on the
adcs.
Useful data quality statistics are
available by selecting the Statistics menu item from the Monitoring
menu on the Experiment Control window. If the ratio of data items
flushed to data items or the ratio of events not acceptable
to events is high then the electronics should be checked.
Events number of good events found
Event
not acceptable total number of events that contain
some type of serious error and are discarded
Buffers
transmitted number of (32 Kbyte) formatted data
buffers sent to the tape server
V767
no START item data was received from a V767 module on
channels 1-128 but no data was received on channel 0. The data is discarded.
SAC
multiple events Even after a retry the SAC event
counter has incremented by more than 1.
****
data items flushed data items discarded during error
recovery. All module data fifos are
flushed following a detected serious error.
****
data items good
data items read. Can be compared with data
items flushed.
Data
word skipped a count of the total number
of data words discarded for any of the
reasons given. This can be compared with the Total data words received.
Transfer
Error there has been a network
error sending to the tape server. The data is discarded. An attempt will be
made to recover the connection.