QHYCCD

image transfer way slower than it should, QHY367 and 600

image transfer way slower than it should, QHY367 and 600
« on: January 28, 2020, 10:38:19 AM »
According to the specs of each camera, they should be able to work at ~3fps in live mode, which would imply ~300ms transfer time. This seems plausible for transfers of ~100Mb over USB3, moreover considering that both cameras should have DDR memory to compensate for latencies.

There is no way I can get anywhere close to that in our linux test setups, using single frame capture. The best I get to, connecting the cameras directly to USB3.2 ports of a fast motherboard with short cables, is ~2.8sec+texp readout time for the QHY600, ~1.9sec+texp for the QHY367.

My call sequence is

Code: [Select]
SetQHYCCDStreamMode(QC.camhandle,0);
ExpQHYCCDSingleFrame(QC.camhandle);
GetQHYCCDSingleFrame(QC.camhandle,QC.pImg);

and the timing breakout I get is: ~100ms in SetQHYCCDStreamMode, ~1ms in ExpQHYCCDSingleFrame and over 2500ms in GetQHYCCDSingleFrame for the QHY600.

I have seen this, https://www.qhyccd.com/bbs/index.php?topic=6861.0, it doesn't help. I understand that there should be two control parameters affecting the transfer speed, CONTROL_SPEED (9) and CONTROL_USBTRAFFIC (12). However, IsQHYCCDControlAvailable() says that only the second is available in the two cameras. Moreover it turns even out that CONTROL_USBTRAFFIC can be set to a value different from 0 only on the QHY600, and has anyway no effect on the timing, at least for me.

Testing environment is Matlab 2019b/Ubuntu18/SDK 6.0.5 (packaged by James Fidell) as usual. Please comment.

Re: image transfer way slower than it should, QHY367 and 600
« Reply #1 on: February 03, 2020, 07:04:53 PM »
Hi,
    You mean you want to let camera work on live mode?If so,you need use these function and setting:
SetQHYCCDStreamMode(QC.camhandle,1);
BeginQHYCCDLive(camhandle);
GetQHYCCDLiveFrame(camhandle,...);
    Or you mean you can't get images when you setup camera work on live mode?
Best Regards,
QinXiaoXu

Re: image transfer way slower than it should, QHY367 and 600
« Reply #2 on: February 04, 2020, 06:10:54 AM »
I mean that in single exposure mode, the time taken by GetQHYCCDSingleFrame() looks to me excessive.