DPA-A Anomalous Shutdown (BEP-A Active)

What is it?

The DPA-A shuts down anomalously, presumably due to a spurious command.

Note

IMPORTANT: The diagnosis and response to the anomaly presented in this document assumes that BEP A, powered by DPA side A, is the active BEP

This anomaly requires human intervention to recover to science operations.

When did it happen before?

The DPA-A has shut down 4 times over the mission:

  • October 26, 2000: 2000:300:15:40, obsid 979

  • December 19, 2002: 2002:353:20:26, obsid 60915

  • January 12, 2015: 2015:012:00:01, obsid 52186

  • December 9, 2016: 2016:344:07:40, obsid 17615

Will it happen again?

It appears likely that the anomaly will occur again.

How is this anomaly diagnosed?

Within a major frame (32.2 seconds), one should see:

  • 1DPPSA (DPA-A Power Supply On/Off) change from 1 to 0 (On to Off)

  • 1DPP0AVO (DPA-A +5V Analog Voltage) drop to 0.0 +/- 0.3 V

  • 1DPICACU (DPA-A Input Current) drop to < 0.2 A

  • DPA-A POWER should go to ~zero

  • 1DP28AVO (DPA-A +28V Input Voltage) is expected to have a small uptick, ~0.5 V, consistent with the load suddenly dropping to zero. May require more than 1 major frame.

  • The software and hardware bilevels will likely not have normal values if BEP side A is active.

All other hardware telemetry should be nominal. The current values for these can be found on our Real-Time Telemetry pages. Older data can be examined from the dump files or the engineering archive.

To extract information from the dump data, run ACORN on it as per the instructions in “Running ACORN on data dumps in the case of an anomaly (04/06/16)”. Information from the tracelog files written by the ACORN tools can be plotted using the Python or command-line interfaces to ACISpy, see below for details.

What is the response?

Our real-time web pages will alert us and the Lead System Engineer will call us. We need to:

  • Send an email to the ACIS team at the official anomaly email address, acis-anomaly -at- googlegroups -dot- com. If it is off-hours, another ACIS Ops team member should call Peter, Bob, and Jim Francis.

  • Send an email to sot_red_alert@cfa announcing that the ACIS team is aware of the DPA-A shutdown and is investigating, and that a telecon will be called when more information is available.

  • Contact the GOT Duty Officer to inform that we need the dump data as soon as possible and to email or call us when the dump file is available.

  • Process the dump data and make sure that there is nothing anomalous in the data BEFORE the shutdown. We want to know if a new occurrence looks just like the previous occurrences. If yes, it should appear as if in one frame the DPA-A turned off.

  • Once analysis of the dump data is complete, convene a telecon at the next reasonable moment with the ACIS team and review the diagnosis. The MIT ACIS team (Peter Ford, Bob Goeke, Mark Bautz, and Bev LaMarr) should also be included in the discussion, either in the telecon or via email. If the diagnosis is consistent with previous DPA-A anomalies, proceed with the recovery. If the diagnosis is not consistent with previous DPA-A anomalies, stop and start a more involved analysis with the ACIS team.

  • As soon as the time of the shutdown is known, inform sot_yellow_alert@cfa.

  • Identify whether or not additional comm time is needed and if so ask the OC/LSE to request it.

  • Send an email to sot_red_alert@cfa and call a telecon with the FOT, SOT, and FDs to brief them on the diagnosis and the plan to develop CAPs to recover.

  • Prepare the CAPs and submit them for review to capreview AT ipa DOT harvard DOT edu, and cc: acisdude. It will also be necessary to call the OC/CC to determine which number should be used for the CAPs. The main recovery CAP will have the following steps:

    A CAP to update txings values from their defaults to most-recent settings should follow the main recovery CAP if possible.

  • Execute the CAPs at the next available comm. Reloading the flight software patches can take a half an hour, so ensure that there is enough time in the comm to execute the entire procedure.

  • Write a shift report and distribute to sot_shift to inform the project that ACIS is restored to its default configuration.

  • Upon warmboot it is essential to update the txings parameters to the most recent values as quickly as possible in order to prevent undesired radiation triggers. CAP 1708 was used at the latest ACIS FSW patch: HJK Version 60. You can use that CAP as a template for this. But you must use the latest txing parameter set (which may not be the values used in 1708). You can find CAP1708_TXINGB_SETPARAMS.docx in acis_docs/CAPs: CAP1708_TXINGB_SETPARAMS. Refer to the most recent txings SAR for the current optimal values for the txings parameters.

Note

As of this writing, the ACIS Flight Software Patch level is standard H, optional J, version = 60. Before preparing the CAPs, check that this is the correct version.

Impacts

  • Until the DPA-A is powered back on, science operations will be interrupted.

  • The warmboot of the BEP will reset the parameters of the TXINGS patch to their defaults. If not updated during initial recovery as above, txings settings should be updated as soon as possible via CAP (see CAP 1708) or SAR to prevent undesired radiation shutdowns.

Relevant Procedures

SOT Procedures

FOT Procedures

  • SOP_ACIS_DPAA_ON (PDF) (DOC)

  • SOP_ACIS_SW_STDHOPTJ (PDF) (DOC)

  • SOT_SI_SET_ACIS_FP_TEMP_TO_M121C (PDF) (DOC)

FOT Scripts

CLD Files

  • 1AWSPOW0002A_206.cld

    • Located at: /data/acis/acis_docs/command_load/1AWSPOW0002A_206.cld and 1AWSPOW0002A_206.txt

CAPs

  • CAP 1708 (Update TXINGS Parameter Values) (PDF) (DOC)

  • CAP 1407 (DPA-A Poweroff Recovery) (PDF) (DOC)

  • CAP 1342 (DPA-A Poweroff Recovery) (PDF) (DOC)

  • CAP 818 (DPA-A Side Recovery from Enabled/Powered Off State) (PDF)

Relevant Notes/Memos