Description
The Master manages and controls the instrument as a physics-acquisition device. It controls instrument activity, including physics acquisition, charge-injection calibration, and subsystem diagnostics (for diagnostics based on the "event path").
The Slaves provide the CPU horsepower for compute-intensive tasks, including physics data filtering and charge-injection calibration.
These tasks can operate in any of several modes, including Event Taking, Calibration, Diagnostic, and Idle (quiescent). Before any of these modes can begin, however, they must perform the Configuration phase.
In Event Taking mode (the primary operation mode), the tasks filter event messages. This is discussed, in detail, in the Event Filtering tutorial.
Calibration mode is used to collect quantitative data on the LAT instrument (e.g., systematic biases). In this mode, the tasks provide artificial signals to portions of the instrument, collecting the resulting data.
Diagnostic mode is used to collect qualitative data on the LAT instrument (e.g., component functionality). In this mode, the tasks operate subsets of the instrument, looking for expected behavior.
Note: An annotated (QuickTime) animation of this diagram is available.
Role: Master
CPU(s): SIU only
Input
The 1553 Receive Service task sends spacecraft telecommand packets to this task.
The GBM Interrupt task sends a notification message to this task.
The LCB Receive Service task sends LAT internal-protocol packets to this task.
Output
The Master task sends requests for operations to its slave tasks.
Role: Slaves
CPU(s): EPUs
Input
The Instrument Physics Master task sends requests for operations to this task.
The LCB Receive Service task sends LAT internal-protocol packets to this task.
The Watchdog Slave tasks send status interrogation requests to this task.
Output
The task sends science and calibration data to the Solid State Recorder.