Re: AP1200 operation via external programs


Bob Denny
 

Jim McMillan:
Consider this scenerio:

1) ACP sends a slew command to the driver
2) The driver interprets this command and sends it to the mount
3) The mount executes the slew
4) ACP asks the driver to tell it when the slew has stopped I'm not
quite sure, but I think this is probably a polling process - e.g.
ACP really continually asks the driver whether the slew is still in
progress.
This is true, but I can't say what other programs (MaxIm, FocusMax,
StarryNight, Cartes duCiel, MaxPoint, MaxIm DL ... well, you get the
point!) will do. The key is that the system (driver + mount)
absolutely MUST be able to report reliably whether slewing has
completed or not!

5) The mount stops
6) The driver tries to determine whether the slew has stopped since
there is no direct feedback from the mount that tells it the slew
has stopped
7) The driver notifies ACP that the slew is no longer going on

Under what condition(s) would #6 not get accomplished such that #7
never happens? And, if those conditions are understood, is there
some failsafe remedy?
Think of the driver and mount as a system. Viewed from the client
program that's what it is. The client could care less whether #6 is
necessary, or if the driver could ask the firmware the question "are
you finished slewing?" One way or 'tother the -system- must be able
RELIABLY report slew completion (well, and everything else reported by
the driver, eh?). Otherwise the response from the "Slewing" property
(etc.) of the driver could be a lie, and no matter WHAT program (ACP,
MaxIm, FocusMax, etc.) is controlling the mount, it will malfunction.
Or, taken another way, the driver must either report the truth, or
raise an error!

-- Bob

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