Executing Commands

• Real time commands are sent from the ground for immediate execution

  • Flight software uses checksum to validate the uplinked data
  • Executive (40 Hz process) sends command to proper destination, either hardware or software

• Block loads are sent from the ground to load command data into stored command processors

  • Each block load contains the address in memory to place the data
  • Each block load can have up to 63 data words
  • Checksum on block load is verified before block is stored in memory
  • Block loads can be designated for any one of three stored command processors
  • Each stored command has some timing information included with it

• Stored commands are executed by the stored command processors

  • Most stored commands are uplinked from the ground and executed once
  • Some stored commands are procedures (e.g. guide star acquisitions) which are left on-board and reused many times
  • Some stored commands are permanently resident and used to respond to safemode situations

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