[guide-user] Scope xtrol

Bill J. Gray Jan 20, 2000

Hi James and David,

A few comments on the scope control situation:

(1) You should probably pay as little attention as possible to the text
on SCOPE.HTM on my Web site (the description of the 'scope driver' system).
I started work on that with great enthusiasm and high hopes, but it turned
out that there were not many people interested in building that sort of
custom motorized telescope. I am not even sure anyone is using it now.
So my efforts have gone elsewhere.

(2) For encoder-based scopes (no motors) that are not JMI/MG-III
compatible, there is a better solution anyway.

A couple of months ago, I heard from a Guide user having problems with
Guide's JMI/MG-III capability. He was running a somewhat unusual system,
including Windoze NT, and we found that Windows programs would not access
the serial ports, but DOS ones would.

We scratched our heads a bit at this, and I eventually came up with what
seemed (at the time) a bizarre workaround. I wrote a small DOS program to
read the encoder position and write it to a little text file. It updated
that file about once a second, and he runs this small program in a separate
DOS shell.

I put a short bit of code in Windows Guide so that, instead of reading
the encoder position "normally" (via the serial port), it gets it from this
continuously updated text file. Aside from that, Guide didn't have to
change at all. The total change in Guide was maybe a dozen lines, which
made things _much_ easier to test.

Until today, I thought of this only as a workaround for one Guide
user. It somehow escaped my attention that this is a great solution for
_any_ customized encoder-based system, much less complicated than the
one described at SCOPE.HTM. This solution just requires you to write a
little 'driver' program to read your hardware (whatever it may be) and
write the encoder position to a small text file. Nothing more. Some
details are now at

http://www.projectpluto.com/scope2.htm

David, this solution (in my humble opinion) is one you ought to consider
very strongly. You might just run the mouse-encoder-reading program on the
main machine, junking the '486 entirely.

(3) Hooking up Mel Bartels' motorized scope system to Guide works in an
entirely different matter. You just use the 'ALTAZ' radio button in the
Settings... Scope Control dialogue. The reason is that by the time Mel
and I started discussing getting our software to communicate, Mel
already had nice software to control his telescope. About all he wanted
from Guide was to send and receive RA/dec data, so that you could click
on an object in Guide and have its RA/dec sent to his software (or so
that his software could send an RA/dec to Guide, and Guide would show a
chart of that chunk of the sky).

-- Bill