[evla-sw-discuss] [Fwd: Re: [evla-mc] More on MIBs...]

[Bill Sahr]

-------- Original Message --------
Subject: Re: [evla-mc] More on MIBs...
Date: Thu, 6 Dec 2001 08:32:03 -0700 (MST)
From: Barry Clark <bclark at aoc.nrao.edu>
To: kryan at zia.aoc.NRAO.EDU, bwaters at zia.aoc.NRAO.EDU
CC: gvanmoor at bclark.aoc.NRAO.EDU,
browen at bclark.aoc.NRAO.EDU,kryan at bclark.aoc.NRAO.EDU,
ghunt at cv3.cv.nrao.edu,bwaters at bclark.aoc.NRAO.EDU,
bclark at bclark.aoc.NRAO.EDU,wkoski at bclark.aoc.NRAO.EDU,
gpeck at bclark.aoc.NRAO.EDU,pnapier at bclark.aoc.NRAO.EDU,
rperley at bclark.aoc.NRAO.EDU,ksowinski at bclark.aoc.NRAO.EDU,
pperley at bclark.aoc.NRAO.EDU,phicks at bclark.aoc.NRAO.EDU,
fowen at bclark.aoc.NRAO.EDU,tcornwell at bclark.aoc.NRAO.EDU,
Brent.Carlson at nrc.ca,Peter.Dewdney at nrc.ca, bsahr at cv3.cv.nrao.edu,
bclark at zia.aoc.NRAO.EDU,kryan at ozone.aoc.NRAO.EDU

The model I had in mind was the VLBA station software, this part of
which 
I consider very successful.  We developed the equivalent of the MIB
driver 
routines and the technician screens first, sometimes while the hardware
was 
still being developed.  Only when we had the screen running and doing
what 
we expected did we start on the equivalent of the antenna object to MIB
section of the software.  This uses the same driver routines developed
for the tech screen.  (For no very good reason we chose to package this
piece of the antenna object with the driver routines, which slightly 
obscures the fact that it belongs to the antenna object, but never
mind.)
It would have been significantly more difficult, I think, to have
developed
the antenna object portion simultaneously with the other pieces.

There will be some things useful to have on the technician screen that 
the antenna object doesn't need to handle.  (An example would be to put
the baseband transmission system into generated pattern mode, as Steve
talked about doing for diagnosis yesterday.)  Everything that the
antenna
object knows about should be on the technician screen.  This also
indicates
that this route of development is the right one.

The only things that get a little complicated with this philosophy are
the
interactions with the operators software.  First, the operator might
like
to know that a technician is using a screen to give commands.  The
screen
needs a mechanism for reporting this to the central system.  Second, the
technician should not be able to issue commands that affect observing
without
the operator giving prior permission.  (A possible solution to the
latter
is for each MIB to have an internal status bit, set and reset by the
operator
through the antenna object, meaning "in use for observing"; the
technician
screen would recognize this bit and refuse to send some commands.)