Date: Sat, 8 Nov 2008 10:52:50 -0600
From: Dan Long
Subject: Re: 2.5m obslog 20081107 (MJD 54778)
>                        APACHE POINT OBSERVATORY SDSS 2.5M
>
>                                  OBSERVING LOG
>                             Friday November  7, 2008
>
>                                   (MJD 54778)
>
>---=== OBSERVING TEAM ===---
>
>Elena Malanushenko  (swing)
>Howard Brewington  (observer)
>Dmitry Bizyaev (observer)
>and MARVELS team:
>Nathan De Lee
>Jiang Peng
>
>
>
>---=== OBSERVING PLAN ===---
>
>         Science!
>7 Nov 2008  54778.0  0.63  MARVELS until 08:26 (7.4 h), then
>BOSS/SEGUE (3.6 h)
>
>
>
>
>---=== OBSERVING SUMMARY ===---
>
>Clear photometric quality sky all night long.
>
>Exposed Marvels survey plates 3076 (c.9), 3077(c.3), 3075 (c.8), 3082 (c.6).
>Got good addition of signal to plate 3161 (c.7), SEGUE.
>
>In the evening, the cartridge lift did not work properly in "auto" position,
>it did not push cartridge more than ~100 lbs. Whole night we worked in
>"manual" position where there was no such problem.
>
    From here in Tucson, I took a look at the PLC bits in the TPM data
from last night.  In the poking around I did, I could not find what
was causing this.  What I can say is that the instrument ID bits
identifying the cartridge are correct, the cart in place bit was
showing correct status, and the cart on lift and compressed on lift
seemed to be indicating proper status.
     Since it works in manual mode, it isn't a hardware problem with
the lift.  It could be something to do with the lift height reading
not matching the expected force.  If something is a little out of
adjustment it could be that the lift is encountering higher forces
associated with mounting the cartridge before it thinks it is at the
right height (essentially the lift height measurement is smaller than
the actual height).
    Try the auto mode again this afternoon.  If it doesn't work,
return to manual mode, and operate with caution as you did last
night.  Please note the time when the auto mode attempt is made, to
help narrow the time search in debugging.  Noting the root causes of
problems associated with instrumentChange (ctrl-leftClick on the
instrumentChange button) when the lift is refusing to go past 100 lb
would also be helpful.
				Cheers,
				  Dan