Cellestron AVX mount with SGPro

Dear all,

I’m a very new beginner trying to play around the SGPro (just purchase it today), I’m trying to find out how to connect my Cellestron AVX mount with SGPro. I used to connect the mount though the guiding camera for PHD2 guiding, now I want to use the SGPro to srew and center the target, I select ‘Generic Hub’ for the Telescope field and it does show connected, but when I try to center the target the SGPro says ‘Slew failed! Illegal operation while parked’. Does anyone know how I should fix this?

Thank you very much!


Hi. You must to install Ascom driver for Celestron mount.

Hello iosif,

Thank you! I’ll try this out, but I’m guessing that I don’t even have the mount connected with the computer correctly in physical. The current connection is the computer talk to the guiding scope, and from guiding scope connect to the mount into the auto guide port, I’m not sure this is the right connection. I google it and find people also talk about using USB to Serial cable and then Serial to RJ11 cord to connect through hand control of the mount, I’m ordering these cables as well.

Thanks again.


Hi iosif, I have installed the Ascom driver as you suggested and I’m happy that I now see a ‘Celestron Telescope Driver’ option available on the dropdown list in SGP, but I can’t see the mount in the computer equipment management panel though I do see the guiding scope there, so I beleive the physical connection between the computer and the mount is not correct. I’ll wait for the cables to come and see if that will may any difference.




I believe I can help as I have the same AVX mount. It’s pretty simple once you understand the connection flow and get the one time setup done.

  1. Get the Celestron ASCOM drivers and install (I believe you have now done this.)

  2. In SGP, go into you Equipment profile (Assuming you have made one for your setup, if not create one).

  • Select Telescope Tab.
  • Under the telescope drop down, select Generic Hub, then click ‘Settings’.
  • This will bring up the ASCOM settings for the Generic Hub. Select ‘Choose Scope’ and select the 'Celestron Telescope Driver’.
  • Press OK. Save your profile.
  1. Just a note before we continue. Any other program you end up using that will need control of your scope, i.e. PHD2, Stellarium, external plate solvers, etc., should ALL be setup to use this Generic Hub.

  2. To attach your AVX to your PC you should only need a USB cable. I believe Celestron went away from serial cables when they introduced the Nexstar + hand controller which you should have. If you have an older Droid smart phone data cable lying around, that should do the trick. Look on the bottom of your hand controller and you will see where it plugs in. That said, DO NOT plug it in yet.

  3. For the hand controller to be ready to accept a connection, you MUST perform the initial mount setup routine after powering on the mount. This includes doing some sort of GoTo align. It doesn’t have to be accurate if you’re going to be using PlateSolve, but you have to run something. I have tried a couple of different things to get around this and it just hasn’t worked.

<Edit 10-15-2018>: Funny, I found a way 2 nights later. If you put the AVX in ‘Hibernate’, either with the hand controller, OR the ‘Set Park’ function under the Telescope module in SGP (What I do when I am done for the night), when you power the mount up the next time, you will be able to immediately connect to the mount. This will allow you to skip the GoTo alignment routine and go straight to your target using the software of your liking, then platesolve & sync. Yes, it will stay in hibernate even if you unplug it.

  1. Once that is done, plug the hand controller into the PC and you should then be able to connect to it from SGPro and any other software using the Generic Hub.

  2. One last thing that I just discovered last night. Apparently, USB Hubs also interfere with this connection, at least the cheap Amazon hub I bought. I believe it’s because this connection is really a USB to Serial driver connection and the Hub interferes with this protocol and doesn’t create the COM port when you plug it in. So, start with a direct USB to PC connection first before you try any Hubs. I had to just rework all my other components and find 2 that worked OK with the Hub and leave the mount connection plugged in directly.

If you run into issues or have any more questions, let me know.

Regards, Stephen

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Hello Stephen,

Just back from holiday leave and see your very detail guide, it is invaluable and much appreciated, thank you! unfortunatelly I have an old hand controller with a RJ11 port at the bottom of it so an USB cable itself will not fit into it. I’m waiting for the USB to Serial cable and the Serial to RJ11 cable which I ordered to come and hope that will work, if not I may need to consider purchasing a newer hand controler that fit with USB cable.

I have instralled the ASCOM driver and created the equipment profile as you suggested, will try the other steps out when I get the cables. I’ll let you know if there is any other issues.

Thank you, Stephen!


No worries. OK, didn’t realize the AVX was ever sold with the older Nexstar hand controller. My AVX is my second Celestron mount and even the first one I bought had the Nexstar + HC. I think it will still work (if by ‘USB to Serial cable’ you mean USB to Serial adapter.), you would just have to deal with the extra cables. I’ve never used that particular setup so I can’t say if there is anything buggy about it, but I have used the serial adapters many times at work and they seem pretty reliable to me.

My only other concern would be the firmware on the hand controller and how compatible it will be with the newer ASCOM driver. That said, ASCOM seems to have some rigorous development rules, and maybe a certain amount of backward compatibility is built in. Firmware can be updated (not hard, they make a utility for that), just not sure how far you could go with the older one. Hopefully, you won’t ‘have’ to buy the newer one.

Believe me, I know how it is. Seems like every time I turn around in this hobby I run into an issue where I either have to learn to live with it, or spend more money to reach my goals! Let me know when you get all the stuff and how it goes. Good luck!

Oh, and just in case, here is the newer one for the AVX if down the line you find you have to or want to upgrade it.



Hey Stephen, my mount was purchased 4 years ago, not too old I’d say :slight_smile: , I’m also wondering why it still use the RJ11 port. Can’t agree with you more that every time come to this hobby I find there are some pieces to purchase or upgrate, but that is partaily the reason it is attractive I guess - there are always something new to learn.

The cables are on their way to my home, hope that will work, but thanks for the link for a newer HC.



Hi Stephen,

I have received the cables and follow your guide I’m able to connect the AVX with my computer correctly, it works! thank you so much.


Awesome, great to hear! Check out the edit to my first post (Item 5). I found out how to connect without doing the GoTo alignment every time.

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