I will give several stupid questions for a better understanding (first time nobody answered them) What is actually Sync? Taking into account difference between current coordinates and expected ones, yes? Is Sync command sent to Celestron telescopes or not? Or is it just KStars accounting for difference?

KStars does not do anything. The mount think it is looking at XX, YY coordinates, when we know for a fact it is looking at AA,ZZ, so we tell it your location now is AA,ZZ and it reports its location as that from now. "Internally" and depending on the firmware, it takes the sync point difference from previously reported point and tries to predict the correct position the next time it moves. KStars simply reports whatever the mount is reporting back.

Ok, clear now, thank you very much! One more question - do I understand it right that Celestron supports only 1-star sync only?

"Depending on firmware" Why does that have anything to do with KStars, or even, the INDI driver for that matter? When I check the box for INDI to use the computer as the "Update source", I expect all commands to flow from KStars to the mount, and, I expect the mount's firmware to be irrelevant to how KStars calculates positions.

The INDI driver for the mount only needs to do 2 things. First, convey a position to the mount by moving the 2 axis motors. Setting the speed of those motors is important, but not absolutely necessary. Second, the driver may receive encoder information, or other data, and pass it along to KStars for interpretation.

All the remaining stuff is within KStars. Time, position, and, location on earth should be user settings within KStars. IF, a particular telescope mount can provide data, fine, but, that is not a requirement for KStars to position a mount. All the version number should do, is tell KStars whether a mount option CAN be used. Then, KStars can pole for that data to allow the user access to additional features.

But, if you want the telescope icon pointing at the south pole, the user should be able to mouse to the south pole on the map, click sync, and KStars should work from those coordinates for directing its actions with the motors. Right now, the Park position, should be the default "starting point" for KStars. If I understand the Celestron Hand Controllers correctly that starting point will be the difference between an Alt AZ value and the users Park value. Still, the user should be able to override the position, by using the map to mouse to a position, click Sync., KStars should then move the icon and work from the new position point.

When a Celestron mount moves to a new location, the INDI driver should allow KStars to pole Alt AZ data from the mount. This data should then update the telescope position icon. This data retrieval can be done at whatever is convenient to the hardware. If no data were available, KStars would still move the mount, and, at the end of such a move, update what position KStars believes the mount is pointing towards. KStars would use for the next move. Based on a visual observation the object was not centered, the user would manually center the desired object and Sync would allow the user to "correct" this position. In a similar sense, astrometry, may Sync the position which KStars is using, OR, astrometry may Sync and then move according to the user's desire to reach a particular ending position.

I will go deeper After powering on (without any pressing on the hand controller) the Celestron mount, how does the motors behave? Are they moved accordingly to the calculated corrections based on alignment stars or only RA motor is moving at sidereal rate? I will explain why this is important. After accomplishing initiating steps on the hand controller, as I can understand, both motors are starting to move at a rate calculated based on alignment. If we try polar alignment using Ekos, as I can understand, it is assumed that only RA motor is working, at sidereal rate. But this is not the case with an aligned Celestron mount... It means polar alignment procedure will be biased by mount's internal alignment, resulting in unachievable polar alignment. So far, do I understand it right?
I tried polar alignment described in the manual of the mount - yes, it helps, but is far from perfect. Even the classical drift method doesn't work as expected because of the both motors working. Am I deeply wrong with all the things I wrote above or it is actually true?

I'm the one trying to develop an AUX-based celestron driver. It is at early alpha stage 3rdparty/indi-nexstarevo). It will be very helpful to me to have this Xmtelremote code as reference/source of ideas/verification of my ideas. Put it somewhere if you can (I have tried googling ... nothing). You can contact me at jochym on gmail.

Please confirm that Astrodan sent you XmTelRemote. If not - I will forward it to you

Not yet, unfortunately. Probably he have not seen my message yet.
I will be grateful for the source - contact me at jochym at gmail

I just sent Pawel the link to my drop box. That should work. Just let me know if doesn't.

Best wishes,
Dan

Got it. Thanks!

I've run into several problems with Celestron driver:
1) GOTO gone crazy. On 20th of May I have been observing Saturn. I pointed to it from the hand control and moved to PC. KStars showed the correct position - near the Saturn. I decided to Sync and... telescope gone wild. It moved tens of degrees away. I chose to Track Saturn - it stayed on the new position. I chose stars around the Saturn - it was moving relative to the new (wrong) position. Here is the log
2) Time update. I set on the hand controller Daylight Saving and Zone 2 (I live in Chisinau, Moldova). When I choose the PC as the source of time and connect the telescope I get on the HC Standard Time and Zone 3
3) Not sure it's the problem of the driver but South button from the Motion Control seems not to work as expected. After I press it second time in order to stop the motion, it actually continue to move. The only way to stop it is pressing North button. Can you please check so I will know if I have problems with the mount?

I've similar problems like fliker09,

Moving from hand control to PC, KStars shows the correct position. When I try to track something from Kstars, the mount slews somewhere else.
Example. I moved the mount to the home position . Changed from HC to PC. Kstars sees the right position.
Then trying to track Arcturus, so expecting the mount to go to the left, but it went right and low.

I'm using the Celestron AVX with newest firmware. Zone 1 , daylight saving.
I tried both celestron nextstar and the celestron gps indi drivers. Same result for both.

The mount control works fine with Stellarium.