THE DAQ COMPONENTS

Midas Data Logger

The Midas data logger is responsible for recording the data. Data can be stored either on the backend machine (useful for small quantities of data) or on the terabyte machine (appropriate for large quantities of data).

The parameter controlling the data logging are contained in two ODB entries, the "Equipment/Logger" sub-directory and "Equipment/Logger/Channels/0/Settings" sub-directory. The sub-directory "Equipment/Logger" includes entries to turn on/off logging to a data file, to turn on/off ODB logging to a ODB file, and specifying the directory for logging. The sub-directory "Equipment/Logger/Channels/0/Settings" includes entries that specify the data buffer for logging (e.g. SYSTEM), the event types for logging (i.e. EVENT ID), the filename for logging (e.g. run%05d.mid), and event limits and byte limits. Also dumping the ODB contents at run start and run end is controlled here.

The data logger is started either from the programs page of the Midas web interface or by typing "mlogger -e mulan -D". The -D option tells the logger to run as a daemon and the -e option tells the logger the name of the experiment. The Midas status page displays if the midas data logger is active (green background) or inactive (red background). It also has statistics on the numbers and rates of data storage.