1. GLAST Large Area Telescope Instrument Flight Software Flight Unit Design Review 16 September 2004 Diagnostics Framework James Swain Stanford Linear Accelerator Center jswain@slac.stanford.edu 650-926-2721 Gamma-ray Large Area Space Telescope

2. 16 September 2004 Flight Unit Peer Review - Diagnostics Framework 2 Diagnostics Requirements Flight Software General Requirements: –5.3.13.2, 5.3.13.2.1, 5.3.13.2.2, 5.3.13.2.3, 5.3.13.2.4, 5.3.13.2.5 Diagnostics During Special Modes –The FSW provides the means to perform on-orbit diagnostics of the ACD, TKR, CAL, and T&DF subsystems through monitoring activities by establishing special configurations and executing algorithms provided by the subsystem designers. FSW shall be able to conduct special diagnostics and return data on: ACD Trigger Mode ACD Pedestal Data CAL Pedestal Value Data CAL Pedestal Histogram Data TKR GTRC Rates

3. 16 September 2004 Flight Unit Peer Review - Diagnostics Framework 3 Functional Components Functional Inputs –Uploaded configuration data, provided by subsystem engineering teams, used to support execution of diagnostics algorithms –Telecommands instructing the FSW to configure the ACD to ACD Trigger Mode, to provide ACD pedestal, CAL pedestal value and histogram data, and TKR GTRC rates Functional Processing –FSW executes diagnostics putting the LAT in ACD Trigger Mode, and collecting ACD Pedestal Data, CAL Pedestal Value Data, CAL Pedestal Histogram Data, TKR GTRC Rates. –FSW executes additional diagnostic algorithms provided by subsystem engineering teams using instrument configurations defined by the subsystem engineering teams These algorithms put the instrument into the necessary configurations and operational modes and set triggers, collect sample events, and generally run the instrument through its paces as needed to perform the diagnostics Functional Outputs –Pedestal data histograms and other diagnostic data sent to the ground in telemetry

4. 16 September 2004 Flight Unit Peer Review - Diagnostics Framework 4 Diagnostics Overview FSW provides a diagnostics capability in two ways: –FSW can execute special-purpose diagnostic algorithms when in Diagnostics Mode –FSW issues a regular diagnostic stream of data in telemetry FSW provides a framework or infrastructure for running special-purpose diagnostics –It is not possible to anticipate every type of diagnostic procedure that may have to be performed –The bulk of the configuration data and diagnostic algorithms will be provided by the ground and executed within the FSW diagnostic framework This framework is scheduled to be implemented as the LDF (LAT Diagnostics Framework) software package –Only those diagnostic algorithms formally specified in the SRS will be implemented in LDF –Additional diagnostic configurations and algorithms must be provided by the ground The basic sequence for running special-purpose diagnostics is: –Put LAT in Diagnostics Mode –Put instrument in desired configuration –Execute diagnostic algorithm(s) –Retrieve results of diagnostic procedure(s) in telemetry or from SSR

5. 16 September 2004 Flight Unit Peer Review - Diagnostics Framework 5 Diagnostic Telemetry: Package Specific FSW also issues regular diagnostic telemetry messages –The content of these messages is defined by the developers [[Comes out 4 times/sec – but many more than 4 diagnostic packets –Will provide a command to retrieve specific diagnostic telem packet on demand, rather than having to wait for cycle]] [[Boot diagnostic telemetry]] [[As an example, ISIS issues the following diagnostic packets]]

6. 16 September 2004 Flight Unit Peer Review - Diagnostics Framework 6 Diagnostics: Telecommands and Telemetry Telecommands –File upload commands to change configuration data for diagnostic runs –File upload commands to change diagnostic algorithms –Command to place LAT in Diagnostics Mode Telemetry –ACD pedestal data histograms –CAL pedestal data –CAL pedestal data histograms –TKR GRTC –Regular diagnostic telemetry messages issued by FSW tasks –Other diagnostic results, depending on the goals of ground- defined diagnostic algorithms