Open Dome Shutter - Number of attempts failing

[Graham Hollis]

Which Version are you running? 2.1

Description

The Open Dome shutter option ‘Number of attempts’ is not working as expected. The Open Dome Shutter option ‘On error’ condition is ignored. The multiple open requests happen very quickly. On rare accasions the shutter magnetic switch sensor does not open a sufficient gap in the time allowed and reports the shutter as being closed. If the dome controller then receives another open command while the gap is still too close, it appears to stop the shutter opening.

Expected behaviour

The instruction Open Dome Shutter has the Number of attempts set to '3' and the On Error set to 'Skip current instruction set'. The expectation is that if the shutter is reported closed after the first attempt, the subsequent attempts to open the shutter will occur after a delay of a few seconds. If all three attempts fail it will not proceed to the next instruction but rather skip all remaining instructions in the set.

Actual behaviour

The instructions contine on with the dome shutter closed. It appears from the log befow is that after the first attemp fails, the second attempts happens immediately which appears to cause the shutter to stop. A 10 seconds delay before each retry would I believe resolve this issue.

The On error condition of ‘Skip current instriction set’ was ignored and the next instruction ‘Enable Dome Sync’ was executed.

2022-11-19T22:43:41.4078|INFO|SequenceItem.cs|Run|206|Starting Category: Dome, Item: OpenDomeShutter
2022-11-19T22:43:41.4088|INFO|DomeVM.cs|OpenShutter|397|Opening dome shutter. Shutter state after opening ShutterClosed
2022-11-19T22:43:41.4148|INFO|AscomDome.cs|OpenShutter|211|Sending an OpenShutter request, since it is currently ShutterClosed
2022-11-19T22:43:44.8449|ERROR|AscomDome.cs|OpenShutter|224|ShutterStatus is still reported as closed after calling OpenShutter.
2022-11-19T22:43:54.8649|INFO|DomeVM.cs|OpenShutter|403|Opened dome shutter. Shutter state after opening ShutterClosed
2022-11-19T22:43:54.8649|INFO|SequenceItem.cs|Run|224|Finishing Category: Dome, Item: OpenDomeShutter
2022-11-19T22:43:54.8659|INFO|SequenceItem.cs|Run|206|Starting Category: Dome, Item: EnableDomeSynchronization
2022-11-19T22:43:54.8679|INFO|DomeVM.cs|OnFollowChanged|664|Dome following enabled
2022-11-19T22:43:56.8691|INFO|DomeVM.cs|SlewToAzimuth|581|Slewing dome to azimuth 359.999789419782°

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Graham

[Stefan B]

Hi,

the Problem you are describing is an internal Problem to the driver. The Opening Command to the driver needs to properly indicate that the dome is in the process of opening, even if the magnetic switch takes a bit of time to do so. This has been discussed in depth also with the ASCOM creators and they also confirmed that this needs to be handled in the driver properly, as the application has no insight about hardware specifics - for example the delay you are requesting is an entirely arbitrary and hardware dependent value, which the application should not have to worry about when using the ASCOM interfaces.

[Graham Hollis]

Thanks for that explanation. I have found a workaround by issuing the open shutter three times with a 10 second delay between each one, so five seperate instructions. If the first one fails it tries again after 10 seconds which seems to work well. The third attempt is just for insurance. If the shutter is open after the first try, the subsequent attemps do nothing and only costs 20 seconds.

The only question that remains from me is why the error in the 4th line of the log above does not make it to the faileditem facility or after retries how it can finish ‘sequence item Dome openshutter’ with the shutter closed without creating an alert to the faileditem facility for alert by GroundStation. It does know the shutter is still closed from the entry ‘Shutter state after opening ShutterClosed’ which is a failed item.

[Stefan B]

I will check why the instruction doesn’t raise an error in this case. It might just not be handled as an error case inside the instruction itself currently.

[Stefan B]

The instruction will raise an error if the shutter state is not reached. Second part of the issue is something that needs to be fixed in the driver.