[evlatests] the ACU and Stowing

[Ken Sowinski]

Steve explained,

> This is how I think this works.   The ACU MIB calculates the pointing 
> and is told to calculate the pointing for the next X minutes.   Even if 
> the network goes down the ACU MIB will continue to talk to the ACU and 
> point the antenna for the specified X minutes.  After the X minutes have 
> expired, the MIB stops talking to the ACU.  If the ACU is not receiving 
> pointing commands, the ACU will auto stow the antenna after a timeout. 
> The timeout is determined by an RC time constant and varies from antenna 
> to antenna but is usually between 5-20 minutes.
> 
> Ken said  “he had a mysterious experience last night …Approximately 40 
> minutes later, the antenna 14 stowed itself and corrected the elevation 
> limit”
> 
> My guess is the ACU MIB stopped talking  so the ACU stowed the antenna.

All that is correct and is more-or-less what I wrote.
X is currently 5 minutes.  Still the question is, is 
the ACU designed to autostow even when the antenna is 
stuck in a limit.  I can no longer remember; perhaps
someone else does.

Ken