QHY695A hangs from time to time. QHY support "blames" SGP

I’m having issues with QHY695A camera and SGP. The problem that camera hangs from time to time, that leads to SGP being unresponsive. And I need to turn on/off camera to get things working back (disconnecting just USB not helping)

I posted this issue on QHY forum, here is the link - https://www.qhyccd.com/bbs/index.php?topic=8211.0
QHY were able to repeat this issue with their own camera. They said the reason that camera hangs occasionally is because SGP keeps requesting filter wheel position with very high frequency. They said that this is not expected behavior and they have not designed their SDK for this scenario. They said that position normally requested when filter is changing, not all the time.

CAn you comment on this, and perhaps change the code so position of filter wheel will be requested with less frequency.

The fact that camera hangs is very annoying, nothing is more annoying that when on the morning you finding out that SGP hanged and most of night time was wasted.


It sounds like they’re planning on addressing it in their driver:

We will fix this issue in SDK to avoid this two IO command run at the same time. Please wait for our new SDK.

Even if we slow it down the possibility for overlapping commands can still happen. If that is an issue in the driver then the driver should address that.

Thank you,

Not sure if they will fix it, but I think it still makes sense to change in SGP, there is no point to query filter position each second, it cannot change all of sudden, so I think even if just only for optimizations reason you could write it in more effective way, right? and as I side effect that will fix my problem or at least will make it much less frequent.

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then again, i have several brands of filter wheels including SX, ZWO and they don’t have a problem with how SGP works, so it kind of looks like QHY is the odd man out

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I agree, if the problem is with QHY, they must fix it, and not rely on other developers to ‘allow’ for their poor product support, which could introduce unforeseen errors for others …

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yes, this is QHY problem, not SGP

ASCOM standard do not specify the max rate you can call driver API, so its QHY responsiblity to fix. they said they will.

but it looks like its more complex though - they said they will need to update camera firmware to fix that problem. hopefully they can do it quickly.

but if the rate of calling filter wheel status can be reduced in SGP code - that will be great too. I dont think there is any point to call for it every second.


I am reading this with great interest, because this could be one of the reasons why my Atik 11000 + EFW3 is freezing up randomly. When I don’t use the filterwheel it never happens. The first reason of this probably that the Atik ASCOM driver doesn’t handle this correctly.
Would it be possible indeed to reduce the polling frequency of the filterwheel ?


I’m following this one, I just received a new QHY camera and am waiting on the new filter wheel.

One question I have is are you connecting the filter wheel through the camera or are you connecting straight to a usb port?

hello. I’ve been working with QHY to test their changes to SDK. I gave them access to my computer with camera connected and they were able to conduct long testing with the latest version of their SDK
so far neither they nor I were able to repeat that hanging issue. I have not tested yet it under real skies, but I’m hopeful the issue is now fixed.

however I’m not sure if this will be related to your camera, I have one of their “all-in-one” series cameras - QHY695A with builtin filter wheel, not sure if this issue even exists with separate filter wheel

anyway, I suggest you to contact QHY through their forum, they seems to be very responsive and willing to help