Transcript Use of Mnemonics

What’s a Mnemonic?
mne·mon·ic (ni-'mä-nik)
adj.
Relating to, assisting, or intended to assist the memory.
n.
A device, such as a formula or rhyme, used as an aid in
remembering.
[Greek mnēmonikos, from mnēmōn, mnēmon-, mindful.]
The American Heritage® Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.
6/22/04
Kickoff LAT Scenario Meeting
1
Command Mnemonics
• Describe an activity
• Fixed and fully defined in the database
• Example:
LHKLIMITCHECK ON or,
LHKLIMITCHECKON
LHKLIMITCHECKOFF
CMDMNEMONIC FIELD=VALUE
where:
CMDMNEMONIC – name of the command mnemonic, as specified in the
database
FIELD – name of a field (parameter or submnemonic) for
CMDMNEMONIC, as specified in the database
VALUE – value for field. Either an expression or the name of a discrete
value for field, as specified in the database. “field=value” may be
shortened to “value” when value is a discrete value and only one of
cmdmnemonic's fields uses that discrete value.
6/22/04
Kickoff LAT Scenario Meeting
2
Command Mnemonic Parameters
• Parameters (fields) further define the action of
the commands
– May be fixed, variable, or invisible
• Fixed parameters may only take on fixed values which are
predetermined and defined in the database (eg. ON, OFF)
• Variable parameters may take on any value within a specified
range of values (eg. ADDRESS=h'7FF')
• Invisible parameters are fixed parameters that can only take
on one predefined value
– Example:
TBLESELECT TABLEID=145, SRCZERO, DESTRAM
6/22/04
Kickoff LAT Scenario Meeting
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How the ISOC Commands the LAT
LAT db
LAT
C&T db
This is the same
LAT C&T db
Project db
ISOC decides what
they want to do
Calibrate LAT with certain conditions or
choices
ISOC uses ground software to
determine the correct CCSDS-format
command to accomplish the desired
function and then convert to the
correct command mnemonic
or determine the correct command
mnemonic directly
...101101101010111010001010100...
mnemonic
LCALIBRATE parm1=1, parm2=x, parm3=523
ISOC sends only the mnemonic and
parameters to the GSSC along with
info on what it is, when to send it,
criticality, etc. *
LCALIBRATE parm1=1, parm2=x, parm3=523
GSSC incorporates the command
into the observatory timeline and
sends it to the MOC
LCALIBRATE parm1=1, parm2=x, parm3=523
LAT
C&T db
MOC uses ITOS and the database to translate the
command mnemonic and parameters back into
the CCSDS format and adds the necessary suffix
and prefix for transmission to the spacecraft
...111000...101101101010111010001010100...0101110...
*In the case of a file upload, the binary data file is formatted for ITOS at the ISOC
using a Perl script (make_load_file_) and the file is sent to GSSC
6/22/04
Kickoff LAT Scenario Meeting
4
ITOS and the Database
• Database contains the descriptions that enable the ITOS
command subsystem to construct binary spacecraft
commands from mnemonic commands entered through
System Test and Operations Language (STOL)
• Database contains the descriptions that enable the
telemetry subsystem to unpack spacecraft telemetry
values from the telemetry stream
– Links values to names (mnemonics), which can be referenced in
STOL or ITOS displays, along with limits and conversions for
each value
6/22/04
Kickoff LAT Scenario Meeting
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