Focuser failed to move to commanded position


I was notified at 9:52PM that my focuser had failed to move to the requested position. I have no reason to believe there was an actual focuser issue as this was the only warning during a multi hour run. It also appears to have happened while focusing as part of the meridian flip.

Link to Logs

Useful Info

OS: Microsoft Windows 10 Pro
.NET: 4.8

AF does not occur at any point during meridian flip. I can’t say what happened without focuser logs. The only thing we know is that we issued a command to move the focuser out by 100 steps and the focuser reported it was done, but the position did not change. Then, shortly afterward, your focuser issued an internal error from the driver…

First we see:

Error in auto focus! Focuser failed to move to the requested position (23766). Focuser reports it is at 23666. : Error in auto focus! Focuser failed to move to the requested position (23766). Focuser reports it is at 23666. at qr.a(AutoFocusData A_0, sz& A_1, sz[] A_2)


ASCOM Focuser: Error in IsMoving wrapper. : Object reference not set to an instance of an object. at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData) at ASCOM.DeviceInterface.IFocuserV2.get_IsMoving() at sx.get_IsMoving() at A_0)

After this, the focuser issue seems to have self-corrected.

“Auto Focus After Automatic Centering” was enabled as was “Auto Center After Meridian Flip” so there would have been an auto focus as part of the meridian flip. I have a moving mirror OTA, so auto focus after meridian flip is required and SGP has been doing it for years.

Target transit time was at 9:35PM and I was taking 10 minute NB subs. So the focuser error at 9:52PM was almost certainly being done as part of the meridian flip logic. This target has few stars so I was using 20 second auto focus exposures which makes the auto focus run take a long time.

I would be happy to supply focuser logs but I have no idea where they might be – or if there are any since I don’t see any option to enable / disable logging in the Gemini focuser software.


Auto focus is applied after the meridian flip, but has nothing to do with it. Other than being executed as subsequent actions in the sequence, they are unrelated. I’m unable to help with focuser logs, but Gemini support folks may be able to help there.