DAQ Software Architecture

The following requirements were considered during the system design:

• provide maximum possible event transfer rate between production and recording processes;
• make the system control easy to use by operator who is not a DAQ expert;
• provide a possibility to add dynamically monitoring programs ensuring that external monitor programs could not affect the main dataflow;
• make the code as much independent as possible from the event format;
• make it easy to reconfigurate the system.

The system should work under Linux OS and has been written in C++.

The requirement to maximize the event transfer rate to the recording process is the most important one. Less priority tasks should not disturb this one by taking system resources. Consequently the system architecture is distributed. It involves one computer (MAIN) for the main task (data taking and recording), one for the system control, one for monitoring daemon. User's monitoring programs can connect to the monitoring daemon either locally or remotely.

Typical configuration is shown on Fig. 2.

Figure 2: Processes: MAIN - main process, FE - front-end process, REC - recording process, MON - provides events for MOND, CTRL - run control program, MOND - monitor daemon, MONCx - user monitoring programs.