[evlatests] the ACU and Stowing

[Tom Frost]

All...

this AM I set up our VLA Servo simulator with both a CCW & Down
1st Limit set....I put the ACU into COMP mode & disconnected the
simulated MODCOMP input....after the specified timeout, the system
indeed auto-stowed itself...even with both an AZ & EL limit set...
there's one datum for you....do the *real* antennas react this way???
I suspect so, but we could try it on MaintDay if you think it would
do some good....

was it designed to do this????...don't know...ask someone that's
been here longer than me (15yrs)....

Ken Sowinski wrote:

> 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
> 

-- 

Tom Frost
Servo Group Leader
National Radio Astronomy Observatory
VLA Site--Plains of San Augustin
New Mexico, USA
web page    www.aoc.nrao.edu/~tfrost/index.htm
e-mail	    tfrost at aoc.nrao.edu