Transcript Diagnostic APID Data discussion

GLAST LAT Project
Gamma-ray Large
Area Space
Telescope
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
GLAST Large Area Telescope
ISOC
Use of LAT Diagnostic APIDs
8 March 2005
Rob Cameron
[email protected]
650-926-2989
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ISOC – Use of Diagnostic APIDs, 8 Mar 2005
GLAST LAT Project
Agenda
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Background: Summarize Alert APID and Diagnostic APID
potential conflict
Review current LAT diagnostic APID telemetry usage
– Unsolicited, solicited, dwell
Determine operational constraints to avoid alert/diag
conflicts
Assess impact of operational constraints
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ISOC – Use of Diagnostic APIDs, 8 Mar 2005
GLAST LAT Project
Background
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Diagnostic Telemetry has the following uses:
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Its use would be limited to specific activities where additional
data is required
– Component checkouts: Calibration data
– Trouble shooting: Table dumps, Memory dumps
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Its use would be limited to specific times
– Scheduled downlinks, lasts for the duration of a contact or
several contacts
– Command driven (MOC, ATS or RTS initiated)
– Event Driven (Fault detection)
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Because of these (agreements from 11/02), Diagnostic telemetry
is assigned same priority (queue) as alert telemetry
– Only difference is the ‘Alert’ APID range initiates a link.
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GLAST LAT Project
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
Background (cont.)
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TDRSS MA link
– 1 kbps downlink for shared Alert and Diagnostic telem
– Presence of Diagnostic telem can impact Alert data
Resulting potential problems from continuous Diag data
– Potential delay of alert data – science impact possible
– Presence of diagnostic data will prevent alert-initiated link
from closing – thermal / power impact possible
• Link closes after 180 seconds with NO data in the
alert/diag queue
– SSR Partition sizing (very minor issue)
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GLAST LAT Project
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
LAT Diagnostic APID Usage
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Unsolicited
– Command Response
• can be turned on, off, or restricted to response only on error
– EPU boot
• rare, but (currently) unlimited duration, until stopped by ground cmd
• NOTE: EPU boot data stream might be put in HSK
– TCS status
• 1700 bits/packet
• can be turned on/off
• can be throttled: 0.1 Hz max packet rate?
• NOTE: most important TCS status will be put in HSK
 Solicited
– MSG system: contents TBD
– MEM: SIU, EPU mem dump, OS and App pool space, symbols
– LFS: directory and file listings, FS status, file dump
– LIM: Instrument manager: contents TBD
 Dwell
– Solicited
– Commanded number of samples
– Higher cadence HSK
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GLAST LAT Project
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
Resolving Any Conflict
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Potential solutions
– SC changes: lower diagnostic priority, diagnostic telemetry
doesn’t keep alert link open ($$$)
– LAT changes: change “routinely if enabled” and “unsolicited”
Diagnostic packets as packets sent across the science data or
HSK channels
– Operational: ISOC keeps all or subset of “routinely if enabled”
features disabled or at low rate during science collection
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GLAST LAT Project
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
Operational Constraints
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TCS
– NOTE: Cannot keep TCS diag on, as the Alert-initiated MA link would never close
EPU Boot
– rare
– NOTE: continuous diag data stream is a concern unless moved to HSK, but assess
impact of extra 3.2 kbps in HSK
MEM
– used infrequently?
– use only during RT for monitoring? (But not a concern for pool space: small dataset)
LFS
– File System Status: monitor at least daily, during RT (but only a small response)
– Directory or Root Listing: used infrequently, only during RT?
– File Dump: use only during RT, and/or use via science stream
MSG, LIM
– TBD impact
– NOTE: ISOC should plan to dump and clear MSG log at least daily, during RT
ITC, command response
– Response should be on for all ATS commands
• low rate, limited response – acceptable impact
– Response can also be on for file uploads during RT
Dwell
– Constraint on ISOC usage, to be assessed case by case
– Duration should be limited as much as possible
NOTE: Should ISOC use diag commanding in ATS, to coincide with planned RT schedule?
– Potential impact on Alert capability if scheduled RT comm is missed
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GLAST LAT Project
ISOC – Use of Diagnostic APIDs, 8 Mar 2005
Considerations from Erik Andrews
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EPU ‘Reboot’ a special case with special considerations
– EPU providing 3.7 kbps of telemetry (is this true?)
– If SA link is ‘on’, then rate is 1, 2, or 4 kbps. (This would be a concern).
– If MA link is ‘on’, then 1 kbps will be the rate.
– Reasonable to buffer/store this data on the SIU?
Command Response – Does a command log exist? Could one be maintained
and then dumped periodically. Would contain cmds and disposition/status.
Errors – Does an error log exist? Would likely include a flag in a tlm packet
header somewhere to indicate errors existed (or log empty/not empty)
TCS, LSW – since not yet built, maybe can use alternative to ‘unsolicited’?
Testing thoughts – What telemetry (of any kind) does FSW need for its FSW testing to verify
requirements?
– What telemetry (of any kind) does DAQ need for its testing of the
subsystem to verify requirements?
– What telemetry (of any kind) does LAT I&T need for its verification and
testing of instrument requirements?
– What telemetry (of any kind) does LAT I&T / ISOC need for Observatory I&T
(or on-orbit) testing and checkout?
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