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Space Shuttle Avionics: Difference between revisions
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→Data transmission errors
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If the IDP cannot exchange information with a GPC, the DPS part of the screen appears crossed out to signal that it is no longer updated. In addition, the MEDS system throws a POLL ERROR message. | If the IDP cannot exchange information with a GPC, the DPS part of the screen appears crossed out to signal that it is no longer updated. In addition, the MEDS system throws a POLL ERROR message. | ||
[[File:Shuttle avionics crossed.jpg|600px|DPS screen with IDP | [[File:Shuttle avionics crossed.jpg|600px|DPS screen with IDP poll error]] | ||
This can happen in two ways: Either there is no GPC available to support the requested major mode (for instance, in nominal launch configuration, no GPC runs system management software and hence any request to show SM DPS screens via the major mode switches leads to the error (since usually three or four GPCs run GNC software, it's unlikely that no GPC out of that redundant set of available). | |||
The other possibility is that the GPC was intentionally isolated using the GNC/CRT key by assigning GPC 0 to the IDP (<b>GPC/CRT 03 EXEC</b> to do this to IDP3). | |||
The situation is resolved by either making a GPC with the requested major function available or by re-connecting the GPC to the IDP in question using the key command. | |||
If an MDU cannot reach an IDP at all, it goes into autonomous mode: | |||
[[File:Shuttle avionics autonomous.jpg|600px|Autonomous Shuttle MDU]] | [[File:Shuttle avionics autonomous.jpg|600px|Autonomous Shuttle MDU]] | ||
Basically the only thing it can try to do is to change ports, and the menu reflects this. If the reconfiguration mode is set to AUTO, the port change is tried automatically, and you may see the failure only as a PORT CHANGE message. | |||
This situation can arise if you accidentially switch an IDP off or if it fails. The situation should be resolved by re-configuring ports such that the MDUs are driven by the functional IDPs as much as this is possible, | |||
== MEDS screens available == | == MEDS screens available == | ||