Re: APPM Questions

Shane Ramotowski

Hi Ray,

I'm currently working on motorizing my dome and am in the middle of testing my newly written ASCOM driver and want to make sure that I can support APPM.

How does APPM send the telescope's destination coordinates to the Dome driver?  Does it do that though ASCOM?

This is my first ASCOM driver, so I'm likely missing something or misunderstanding something, but I don't see any ASCOM methods that would work for sending telescope coordinates.  Is it done though a custom command in Action(), CommandBlind(), CommandBool(), or CommandString()?  I know about the CanSlave property, but as I understand it, that is for a hardware (external to DOME driver) solution.

Thanks - Shane

On 10/5/2020 8:56 PM, Ray Gralak wrote:

APPM sends the telescope's destination coordinates to the Dome driver that to which APPM is configured. IMO the Dome driver should be intelligent enough to figure out where the telescope is heading and move the dome there. I would say it is up to the Dome driver developer to make this work. I would say you should talk to the NexDome manufacturer to see what suggestions they have.

Also, I have been on and off working on a generic cross-platform dome driver. At the rate it's been going, it may be months away from when I can complete it, but the intent is to fix some of the bad decisions (in hindsight) made by ASCOM in the API design. (Then I would have to convince application developers to implement what is essentially a superset of ASCOM.)

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center):
Author of Astro-Physics V2 ASCOM Driver:

-----Original Message-----
From: [] On Behalf Of Tony Benjamin
Sent: Monday, October 5, 2020 7:42 AM
Subject: Re: [ap-gto] APPM Questions


Is my understanding on this whole process more or less correct?:

* as soon as I hit "Start" for the APPM run that first RA/Dec (Zenith) is sent to SGP (assuming I'm using SGP
for dome movement);
* SGP does the math required to figure out what Azimuth to send the dome to (should take like a Nano
second - it is a computer after all); and
* that Azimuth position is then sent to the Nexdome driver which then actually has the dome move?

Is that the way things should work? If so, then I would be guessing that the Nexdome driver may be the real issue
in all this?

Shane Ramotowski

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