ZWO EAF sporadicly disconnects [DriverAccessCOMException]

[Renden Yoder]

Issue is reproducible
I am running the latest version
All prerequisites that are mentioned are inside the manual met

Description

When using the ZWO EAF with NINA, the focuser randomly disconnects itself.

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I have encountered others on online forums with the same issue. I have tried different usb cables, usb ports, and usb hubs which makes me think it is an issue with ZWO’s provided ASCOM driver. ZWO released a new driver on 7/2/2020 yet the issue still persists. I know this issue is likely an issue with ZWO’s driver but perhaps a try/catch wouldn’t be too egregious.

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Over the last two weeks I have been running NINA from source and have added a try/catch in NINA/Model/MyFocuser/AscomFocuser.IsMoving for a DriverAccessCOMException and am logging it when it occurs. My focuser has remained connected and able to autofocus throughout the night.

Pull request is ready to be made if this issue is deemed worthy.

Steps to Reproduce

• Connect a ZWO EAF
• At some point over the next few hours the connector will disconnect itself. (This happens every night for me)

Expected behaviour

ZWO EAF should not disconnect itself.

Actual behaviour

ZWO EAF disconnects itself.

[Dale Ghent]

Have you raised this issue with ZWO support? Have they acknowledged that this is an issue they can issue a fix for?

Generally, If the driver is failing internally the preference is to get that fixed by the vendor before attempting to paper over it in the application. Since catching exceptions can be indiscriminate regarding their cause, this can have implications in truly fatal error cases.

[Renden Yoder]

Hi @Dale Ghent , thanks for the quick response!

I have tried to reach to ZWO regarding this issue and have never been able to get a response so I tried to go about fixing the issue.

I completely agree that (if the issue is indeed with the ASCOM driver) the solution is for ZWO to update/fix their driver. However, I don’t think they are going to respond at this point haha I can try to reach out once again and update this issue accordingly.

In the meantime, is there any fix that would you would deem suitable?

[Stefan B]

What would be the error handling in that case? Returning either false or true when this issue occurs can cause weird side effects.

[Dale Ghent]

One major consideration with catching this kind of exception and trying to pretend that everything is ok is the case where there really is a malfunction in the driver and NINA then enters an unabated loop of catching the exception, reconnecting the driver, it throwing again, ad infinitum. We cannot think that this specific example of the ZWO driver will characterize all cases. DriverAccessCOMException is a rather general yet fatal and deep-seated error. Encountering it requires some particular attention.

Another wondering I have is why haven’t we heard of this problem before given the rather prolific use of the ZWO EAF among NINA users, myself included? I’m wondering if this is a problem with your specific setup; either the driver and the ASCOM version you are using (6.4sp1? 6.5?) or some other combination of local factors. IS there any additional text that is provided by the exception?

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[Renden Yoder]

Here is the error found in the log. I didn’t find out it was a DriverAccessCOMException until I did a little investigation. I know at least one other person with the same issue (I know that’s anecdotal).

I should be using the latest of both the ASCOM and ZWO EAF drivers. I have tried uninstall and reinstalling multiple times to fix the issue with no success.

[2020-10-10T03:30:58.8599]   [ERROR]     [MemberName] IsMoving
[2020-10-10T03:30:58.8599]   [ERROR]     [FileName] C:\Users\Rende\Documents\Developer\nina\NINA\Model\MyFocuser\AscomFocuser.cs
[2020-10-10T03:30:58.8599]   [ERROR]     [Message] IsMoving Failure    at ASCOM.DriverAccess.MemberFactory.CallMember(Int32 memberCode, String memberName, Type[] parameterTypes, Object[] parms) in C:\ASCOM Build\Export\ASCOM.DriverAccess\MemberFactory.cs:line 288
   at ASCOM.DriverAccess.Focuser.get_IsMoving() in C:\ASCOM Build\Export\ASCOM.DriverAccess\Focuser.cs:line 80
   at NINA.Model.MyFocuser.AscomFocuser.get_IsMoving() in C:\Users\Rende\Documents\Developer\nina\NINA\Model\MyFocuser\AscomFocuser.cs:line 65

If the exception is too generic and fatal to be caught then lets just close the issue.

[Janos Barabas]

Hi,

Could you please elaborate what was the solution for this issue, I experience exactly the same behaviour with my ZWO EAF in Nina,

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Clear skies,

Janos

[Renden Yoder]

Hi @Janos Barabas ,

I recently switch to using a mini PC rather than the laptop I had been using and the issue has yet to rear its ugly head even though both the laptop and mini PC are near clones.

I believe the issue was that my ZWO EAF was sharing a usb port with other devices. I had my ZWO EAF, Pegasus Astro Pocket Powerbox, and Celestron Advanced VX plugged into a usb hub which then plugged into a USB 3.0 port.

Try plugging in your ZWO EAF into its own USB port on your machine and see if that resolves the issue as I suspect it might.

[Janos Barabas]

Hi Renden,

Thanks for replying, I will try that remedy !

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CS,

Janos