Appendix A2 - Recovering From Unexpected Memory Upsets - Dawn CONTROL-1500A Manual

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CONTROL-1500A Single Axis Antenna Controller Appendix A2 Unexpected Memory Upsets

Appendix A2 - Recovering From Unexpected Memory Upsets

The key to restoring the non-volatile memory is getting the azimuth and elevation limits and
position counts right. The position counts are initialized to 30 when the east and down limits
are set. If the antenna can be unambiguously placed at the east and down limits, non-volatile
memory can be restored quite easily. It is probably a good idea to use a punch or a waterproof
magic marker to mark the antenna and mount assembly so that the east and down limit
positions can be identified. In addition, it may useful to identify and mark other places on the
mount where slippage could occur. This would allow the mount to be restored to its original
configuration.
If the contents of non-volatile memory are recorded as outlined in steps 1-4 above, recovery
from an unexpected memory upset can be readily accomplished. If the memory is corrupted,
the antenna can be moved (in LIMITS mode) to the east and down limit with the aid of an
assistant stationed at the antenna. Next, steps 7-9 can be used to restore the contents of non-
volatile memory.
Note that the procedure for restoring non-volatile memory only works if the count
characteristics of the actuators are not changed. If the actuator count characteristics are
changed, the count values that correspond to the west and up limit will change, as will the
positions of all of the satellites.
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