ASI120MM dropped frames

furrysocks2
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ASI120MM dropped frames

Post by furrysocks2 » Sat Sep 22, 2018 8:13 am

In fact, it's a Datyson T7M, but as far as I know, it's a clone.

With the latest ZWO drivers, and latest SharpCap 3.1 and 3.2b, I'm getting dropped frames in MONO16. Seems ok in MONO8, but when I switch to MONO16 and set exposure >1s, I get 100% dropped frames. Below 1s, I get frames ok. I tried dropping Turbo USB and to a point, it helps, but the image can corrupt - the right side of the pic on the left, etc. I tried using ASICAP as a comparison, and it appears to be happy with >1s RAW16.

I'm happy to help with any debug/testing - does this sound either familiar or resolvable?

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admin
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Re: ASI120MM dropped frames

Post by admin » Sat Sep 22, 2018 2:33 pm

Hi,

this is an issue that I have investigated before and not come up with any solution - basically the 120MM/MC on USB2 can end up dropping frames in the case of 16 bit mode and longer exposures. In some cases turning down the Turbo USB setting may help. You may find that using an older version of SharpCap (that has an older version of the ZWO code) works better for this particular situation - for instance try SharpCap 3.0

cheers,

Robin

furrysocks2
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Re: ASI120MM dropped frames

Post by furrysocks2 » Sat Sep 22, 2018 9:27 pm

Thanks, Robin.

That's unfortunate. However, I've had a play an appear to be getting reliable operation with 3.2b in a USB 3.0 port, but consistently unreliable under USB 2.0.

Would you expect this, or know why that might be?

Regards,
Matt.

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Re: ASI120MM dropped frames

Post by admin » Sat Sep 22, 2018 9:31 pm

The USB2 versions of this camera operate at a non-standard USB packet size to squeeze a higher frame rate out than would normally be achievable. It's possible that your USB2 port is less than happy with this non-standard tweak but the USB3 port copes better with it.

The USB3 versions of the camera (a) have the much higher bandwidth of USB3 available and (b) have a larger internal buffer, which makes then much less sensitive to USB glitches.

cheers,

Robin

furrysocks2
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Re: ASI120MM dropped frames

Post by furrysocks2 » Sat Sep 22, 2018 9:46 pm

OK - I'm assuming they exhibit the tweak even at low frame rates/long exposures?

In any case, I think I have the workaround I need to operate the camera with latest SharpCap.

Recently renewed pro - thanks again for all your work.
Matt

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Re: ASI120MM dropped frames

Post by admin » Sat Sep 22, 2018 9:51 pm

Yes, it's a very low level thing. There used to be a firmware updater and alternate camera firmware (on the ZWO site) that you could use to put it back to the normal packet size - this was needed for either Mac or Linux compatibility (can't remember which). Mind you, if it's working now I wouldn't go trying that!

cheers,

Robin

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Re: ASI120MM dropped frames

Post by furrysocks2 » Sat Sep 22, 2018 10:04 pm

I found that last night - FWTool.zip with various files names <camera>.iic and <camera>-compatible.iic - but with no accompanying explanation.

A quick search just now brought up the difference being between 512 byte packets ("compatible") and 1024 (non-standard but better performance).
https://bbs.astronomy-imaging-camera.co ... =17&t=6124

As it appears to work in a USB 3.0 port, I will leave the firmware untouched for now.

Apologies if this is something you've already had to answer here. Many thanks for your help.
Matt.

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Re: ASI120MM dropped frames

Post by turfpit » Sun Sep 23, 2018 8:47 am

Matt

I see ZWO are making this harder to find. There are only 2 choices for each of the relevant camera models. It is possible to regress the firmware update (I have done it).
ASI-firmware.PNG
ASI-firmware.PNG (6.08 KiB) Viewed 1378 times

As you say -you have found a port that works - the sensible, zero risk and easiest option is to use the camera on that port.


Robin -
*Note:Our USB2.0 camera is not compatible very well with Mac OSX & Linux. USB3.0 cameras is recommended for Mac & Linux users and fully compatible with USB2.0 host.this thread may help you if you want to try our USB2.0 cameras on Mac OSX.
This quote is from the ZWO developers on their website/BBS.

This is the thread of interest https://bbs.astronomy-imaging-camera.co ... lit=NikkiM

The issue was RAW16 exposures of > 1s - massive packet drop - this was on Linux (and it looks like Macs had the same). The developers ran up against a group of people who write capture programs on Linux as a hobby. ZWO initially tried to blame the USB bus of the capture PC but it was quickly pointed out to them that RGB24 works.

Ultimately, NiKkiM (Nicola Mackin FRAS), produced a fix which involved the firmware upgrade above plus a hack and recompile of the Linux kernel - which I can confirm works. Not something to take on lightly. Linux kernel 4.14 and higher accommodate this and the kernel hack is no longer needed. The USB3 version of the camera does not have the issue.

Dave

bgirrell
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Re: ASI120MM dropped frames

Post by bgirrell » Sat Apr 20, 2019 9:21 pm

I just went through a bout of this with a ZWO ASI174MM. Perhaps this might help point toward a culprit. If not, maybe someone faced with the same issue might be helped by what I found out.

All image sizes worked in 8-bit and everything worked in 16-bit up to and including image sizes of 1216x1216, but I had 100% dropped frames at any sizes larger than that. I downloaded and reinstalled SharpCap and the ZWO driver. Still the same. Testing of the camera on another system eliminated the camera and cable. Everything pointed to a USB problem and I eventually ended up spending close to two hours with a very patient Microsoft support agent attempting to help me diagnose my computer's USB issue and eventually discovered this thread.

Eventually we discovered that the Turbo USB setting had found its way up to 100. I don't know how this happened other than I am using a Surface tablet for acquisition and I may have fat-fingered something on the screen. Needless to say, since I never use the control, I wasn't checking its setting. But the instant that he moved the pointer from 100, the camera started working. I'm not sure why the reinstall didn't solve this. For all TurboUSB values other than 100, everything works fine.

Checking the documentation, I see that setting this control too high can lead to loss of frames, but I really don't understand what the control is trying to do, nor why setting it to use maximum USB would cause it to completely fail. I have seen the engineers I worked with tear their hair out over USB many times, so I'm not going to hold much hope for a solution. This one seems to be repeatable for me though, so perhaps there might be a chance to find something.

Bruce G

PeterO
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Re: ASI120MM dropped frames

Post by PeterO » Fri May 17, 2019 2:32 pm

I had the same problem with dropped frames using a USB2 version of the ASI 120mm camera with SharpCap 3.2.
It seems to have been partially fixed by using a USB-B to USB-C USB-3.1 cable to connect the camera to a USB-3 type USB-C port
But it needs to have the capture setting reset and then activated after which it captures the requested number of shots and then stays running in preview mode. If I change the exposure setting then it starts to drop frames until I've reset and activated the capture mode again.

Its as if there's a reset needed or buffer that has to be cleared after changing the exposure setting?

Regards, Peter
Last edited by PeterO on Sat May 18, 2019 12:14 am, edited 2 times in total.

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