I still need to do more testing but not sending the #SM:XXXXXXX! and #Sm:XXXXXXX! seems to cure the problem.
I first removed the leading padding with nulls (%07d replaced with %d) from the SM commands but that did not help
The Sesto app sends the focuser to a position and then uses the #SM! command, maybe thats their workaround.

I will now do some more extensive testing and if this works see if I can come up with a work around OR we simply accept that the initialisation is done from the Sesto app. I must say I am leaning towards letting the Sesto app do the initialisation . The less the Indi driver has to do the more stable and future proof it is.

@Jasem, if you can send a mail to PrimaLucelabs then I can ask them if there are any known issues (they will only talk to me if you say its OK) with these commands.

Maybe it is the ";" that is causing the issue? The GoTo command doesn't need this extra separator.

Just tried that but it doesn't help.

I am pretty convinced now that its the SM and Sm commands that mess things up. As soon as I stop sending these commands the focuser works perfectly.

My suggestion is to remove the ability to set the max position but still display it. That way we have the feedback to know its still OK but we can no longer set the max position. If you want to alter the max position use the Sesto app.
OR
We could add a button to set the current position as the max as this does not seem to cause any issues.

If that is the way to get it work, it would be fine for me! I do not need to set the maximum position in Ekos anyway, because that is done by calibration with the PrimaLuceLab software. From my point of view it is enough that Ekos knows the maximum (and minimum) position and doesn’t let the Sesto Senso go beyond these positions during the Autofocus or by a manual desired focus position.

Thank you for all that awesome work!

I agree.

Does anyone else have a Sesto Senso on the StellarMate/RPi or Ubuntu?
If so I would like to send you the library so we can confirm that this does solve the problem.

I have the configuration you require..

If you send me the library (and instructions about how to install it) I can try this evening...

Paco L.

Thank you for all the great work guys!! I just emailed PrimaLuca and asked them if they have an explanation for this. If we don't get any response, we can just comment it out.

Is the Windows software sending out any different/extra commands on startup if you snoop via WireShark?

They start with #MF!#GC!#GS!#QF!#QSN! then they repeat #QP!#QT!
During calibration they use #Sm;0! to set the min point and use #SM!#PS! to set the max point.

#SM! is sent without any position? so during calibration, the focuser is moved to some location and then #SM! is sent?

Sorry, forgot you do not have one.
Calibration is in 3 steps:
1) Set the focuser at 50% position manually
2) Move to zero using the motor, when you move to next step => #Sm;0!
3) Move to max using the motor, when you say done => #SM!#PS!

and no where is #SM;xxxxxxx! command used? Maybe that's the command causing the issue? we could implement calibration in the driver similar to what they have in Windows.

Exactly. We could or just leave the calibration in the Sesto App and just report on the max value. I like the idea of keeping the Indi drivers simple.

One thing I still need to look at is what is does with the Ascom driver.