Data Logger
The Midas data logger serves multiple purpose of logging.
- Its main task is to log experimental data to storage device(s) such as disk, tape, FTP.
- Serves the logging of the overall Midas system messages
- Collect and log the history events
- Can log special information to an external mySQL database
logging System messages to a Message file or as message events logging Experimental data to storage device(s) such as disk or tape Multiple Logging Channels can be defined several different storage devices, formats and compression levels can be selected data can be logged to different subdirectories on disk data can be logged to a remote computer, using the FTP mode events can be selected for logging by Event ID or Trigger mask Event Filtering can be implemented runs can be automatically stopped and restarted after a certain number of events, or a certain time the complete ODB contents can be saved into a file at the beginning and/or end of run and/or into the data stream logging information to a mySQL database writing information to an electronic logbook collecting and logging history events When the MIDAS logger (mlogger) is started for the first time, it creates the /Logger ODB tree (including a single logger channel - channel 0), and fills it with default settings. The /Logger tree contains all the relevant information for mlogger to run properly. The user has no code to write in order for the system to operate correctly. However, the user will want to customize the logger for his/her own experiment, by setting the keys in the /Logger tree to suitable values.
In addition to the /Logger tree, mlogger also creates the /History and /Elog ODB trees, used in the optional History and Electronic Logbook features. If MIDAS is compiled with mySQL support, a mySQL subtree will also be created in the /Logger tree (see Logging information to a mySQL database). All these features are described in the following pages.
The data channels as well as the history logging are rescanned automatically at each start transition. In other words, additional logging channels can be defined while running, but the effect will take place only at the following start transition. The mlogger utility runs on the backend computer, receiving events from the buffer manager. It supports three type of storage devices so far, i.e.
Disk, Tape FTP channel to a remote computer. Data can currently be written in five different formats :
MIDAS binary, ASCII, ROOT DUMP The user may of course write their own custom data logger to save the data in any format they choose.
- [[Data storage options →
- data compression → '
- Secondary data logging (lazylogger) → '