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Celestron Nexstar+ handset: Remote Align?

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Apologies, its not really an INDI or EKOS question...
I have upgraded my CPC1100 with a new Nexstar+ handset. This handset has a USB socket instead of the old rs232 serial and also supports the hibernate serial commands. Its working great, hibernate works from indi and I have a much more reliable system and was able to scrap my hibernate workaround .

However, for some reason today it lost its hibernation state and now the scope is not usable via INDI. I need to be physically there to do the handset alignment procedure which is not possible without spending 2hrs in a car. So my question is... Is it somehow possible to remotely do the align procedure for a celestron mount?
I see there is an app called Nexremote but i have no idea if all the required features are exposed over the serial interface....

Thanks!
Derek
7 years 4 months ago #12682

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I have no idea, it is best to ask Celeston or perhaps in a Celestron forum. It all boils down to if they have some RS232 commands to perform that.
7 years 4 months ago #12687

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Hi,

did you manage to solve this problem, I have a similar issue?

Regards
5 years 4 months ago #31451

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Hi Petrush,

Yes I actually did and now have a very reliable system for the last 12 months or so with my CPC1100. I can sync/align the mount remotely from a cold power on.

I wrote my own mount control software from scratch which runs on a PC in the observatory. Its the same PC running INDI and Kstars. I called it AUX-REMOTE. The handset for the mount plugs into the PC via USB and AUX-REMOTE sends AUX commands directly to the mount's motor controllers through the handset. Essentially the handset is not used except as a convenient cable to pass commands to the mount. If I had the correct cable I could have plugged directly into the mount and not used the handset.
I also wrote an indi driver for this mount control system....
So basically they way it works for me: EKOS talks to the INDI driver. The INDI driver talks to AUX-REMOTE which talks to the motor controllers over USB. It is an extra layer of software between the INDI driver and the mount but for me its working really well.
Park and unpark work perfect. Once it unparks, it sends a sync command to the motor controllers to tell it where it is pointing. Guide, slew, track work perfect, I even implemented PEC training but I actually dont use it.
If you want more info on it, the code is here, github.com/dokeeffe/auxremote
Send me an email/message if you need more info.
Derek
5 years 4 months ago #31460

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The short answer is that it isn't possible to do an alignment remotely beause the align commands are'nt available in the command set. By align I mean the sort of alignment using pointing to multiple objects in the way that you do using the HC. Also the alignment depends on the mount starting at the home position with the hour angle axis at 6hrs and the dec axis at +90 deg.

There are things that you can do.
The current Park and Unpark processes do to samr as the HC hibernate and Wake up, this allows an alignment that has already been done to be recovered.

The snag with this is that it requires that the mount is parked before the power is turned off, if the power is just turned off then the mount position is unknown.

With most mounts there is very little that can be done because the starting position of the mount is unknown. It's assumed that the position is +90 in Dec and 6/18 hrs in hour angle.but there's no way to tell or in most cases to get there. The exception is for the mounts that have home switches where a command exists to drive to the home switch position. with this it should be possible to do the equivalent of a quick align by driving the motors to the home switch position and setting the axis positions. It's possible to operate from that by doing a solve and sync to get a good local alignment.

Doing a solve and sync from where the mount happens to be pointing might work but only if the scope can see the sky and in the case of a mount in a dome the scope may not be able to see out. There's also a pathological case if the mount happens to have tracked past the meridian.

Chris
5 years 4 months ago #31475

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Hi Dokeeffe,

Thanks for the response, this looks interesting! I will try to get it to compile and try it!
5 years 4 months ago #31499

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Chris,

Yes, the problem I have is it seems like it is not possible to do a slew and sync with the telescope if the align on the HC is missing. The solve may be successful but it seems like the sync isn't working. I may (hope) be wrong, but cannot find any way to do a sync before that. After a HC align the sync works.
5 years 4 months ago #31500

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Hi Derek,

I was playing around with your auxremote driver today and finally got it to run on the raspberry.

It seems like, and now found a note in the source that it is only for equatorial mounting. Do you have plans for developing support for alt/az mounts? I will have a look at the source and see if I can find it, but usually quite tricky to understand code..

For curiosity, why did you choose this architecture with a java server that interfaces the INDI driver?

Regards
/Petrus
5 years 4 months ago #31534

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Hi Petrus,

Yes it only works with the mount in EQ mode on a wedge. I was going to add an ALT-AZ support but its quite a bit of work and the EQ mode works well for me now.
To implement ALT-AZ the java app will have to send constant speed changes to both motors every 10seconds or so after re-calculating the direction based on current pointing position and gps location.

The reason I implemented this architecture is that I'm more familiar with writing java services and how to test (unit test) applications in Java. In theory I could have implemented the exact same functionality inside a new indi dirver in c++ but I'm not familiar enough with c++ and testing these applications to be able to write a rock-solid tested application. The java service has 90% code coverage with tests and I think/hope I've caught most bugs by doing that.

Derek

P.S. there actually is a driver that uses the AUX protocol to talk directly to the motor controllers (bypassing the handset) but its still in early alpha stage.
github.com/indilib/indi/tree/master/3rdparty/indi-nexstarevo.
Last edit: 5 years 4 months ago by Derek.
5 years 4 months ago #31536

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