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Celestron Nexstar NexRemote PTZ control
By: JohnMa
Rank: Frequent User
Topics: 31
From: n/a
Added: 10/30/2009 - 12:44 AM

I would like to mount a webcam on a Celestron "Nexstar" telescope for remote viewing. Is there any chance AbelCam could be used for the PTZ control of the telescope?

see the Celestron site for details of the equipment

http://www.celestron.com/c3/product.php?ProdID=327
By: sse
Rank: Forum Addict
Topics: 73
From: n/a
Added: 10/30/2009 - 03:01 AM

Currently no RS232 PTZ control is implemented in AbelCam.

Send me a telescope and I'll implement the controls Wink

Is there a specification of the protocol?
By: JohnMa
Rank: Frequent User
Topics: 31
From: n/a
Added: 10/30/2009 - 05:45 AM

Yes, there is a protocol spec for the Celestron NexStar series:

http://www.celestron.com/c3/images/files/downloads/1154108406_nexstarcommprot.pdf

Speaking of RS232, I also have a couple of old Panasonic KXC-CM775 ptz camera, which have really excellent optical zoom. They use RS232 control. The only program I have found to drive them is a program called BDLCAM, which provides the PTZ control, but not the webserver for the video. I think I can find the serial control protocol spec somewhere.
By: sse
Rank: Forum Addict
Topics: 73
From: n/a
Added: 10/30/2009 - 08:09 PM

The specs look fine.
This could be implemented in a plugin.

Volunteers please step forward Wink
By: JohnMa
Rank: Frequent User
Topics: 31
From: n/a
Added: 01/27/2010 - 11:12 PM

Message has been edited, click here to see original content

Message has been edited, click here to see original content

Is there a tutorial or some instructional material somewhere on how to write a plugin? I haven't ever done anything like that, but if I knew where to get started I might have a try at it. Are plugins coded in javascript, or what? I assume there are specific formats or protocols for AbelCam plugins? I have done a little minor programming in the distant past, and have done things like editing html code, but I would be starting from the very basics.

OK, I actually tried reading your instructions and found the section on writing plugins. Sounds complicated. I'm not sure what "any .net language" includes, which just goes to show how little I know, but that would be a start.
By: MelvinG
Rank: Magna Cum Laude
Topics: 661
From: Los Angeles, USA
Added: 01/28/2010 - 01:20 AM

Sounds to me like you need to take a look at the Developer Tools section on Microsoft's website as a starting point. That will tell you a bunch about .NET and such. You'll need Visual Studio 2008 first of all. The "Express Edition" might still be free - dunno for sure - and if it is, get it. It's a limited version of Visual Studio but it is certainly adequate for writing plugins.

There are 2 .NET languages that I'm sure can be used for plugin writing: VisualBasic and VisualC# ("C-sharp"). Which is the better one to use? Matter of opinion. I prefer C#, others may say otherwise. Both the plugins that I wrote were done with C# (and in the case of the K8055 plugin parts of it are in native C++, in a DLL, for easy access to the WinAPI).

I find the AbelCam <--> Plugin interface easy and straightforward to deal with. Writing the "guts" of the plugin (the code that implements whatever your plugin actually does) can range from trivial to quite difficult, depending on what you're trying to accomplish, how much of a user interface you need, etc.

I will say that IMHO dealing with serial communication is not for the faint of heart. Unidirectional serial (you throw commands at the remote device but it never talks back) is not so bad. Bidirectional serial can get hairy - at a minimum you'll need to write an event handler to deal with data from the device arriving "at random", and if your application actually needs that data for anything (likely) things can get quite "interesting".

Also, keep in mind your code will be acting as an extension of a webserver. In short, that means that your plugin's getText(), getHtml() and/or getImage() methods (in your case, whichever method implements PTZ - probably getHtml()) have to implement some sort of request queueing and deal with global resources (eg. the serial port) in a thread-safe manner.