Hello,
I am a collaborator of the project that Zerjillo says, as he has commented, it seems that time is always double the exposition time. It seems that time is wasted reading from the usb.
Attached the log using 5 seconds as the exposition time:
INFO 235.059428 sec : Session log file /home/ainokila/.indi/logs/2020-10-01/indi_qhy_ccd/indi_qhy_ccd_17:03:21.log
DEBUG 247.092961 sec : Requested exposure time is 5000000 us
DEBUG 247.092995 sec : QHYCCD|QHYCCD.CPP|SetQHYCCDBinMode|START
DEBUG 247.414244 sec : QHYCCD|QHYCCD.CPP|SetQHYCCDBinMode|END ret = 0
DEBUG 247.414274 sec : SetQHYCCDBinMode (1x1).
DEBUG 247.414295 sec : QHYCCD|QHYCCD.CPP|SetQHYCCDResolution|SetQHYCCDResolution|x = 0 y = 0 xsize = 1280 ysize = 1024
DEBUG 247.414308 sec : QHYCCD|QHYCCD.CPP|SetQHYCCDResolution|END ret = 0
DEBUG 247.414315 sec : SetQHYCCDResolution x: 0 y: 0 w: 1280 h: 1024
DEBUG 247.414322 sec : QHYCCD|QHYCCD.CPP|ExpQHYCCDSingleFrame (BeginSingleExposure) | START
DEBUG 247.414331 sec : QHYCCD| QHY5.CPP | BeginSingleExposure
DEBUG 247.414336 sec : QHYCCD| QHY5.CPP | Call setParameters camgain 10
DEBUG 247.735656 sec : QHYCCD|QHYBASE.H|StartRemainingTimesCount
DEBUG 247.735686 sec : QHYCCD|QHYCCD.CPP|ExpQHYCCDSingleFrame (BeginSingleExposure) | return value=8193
DEBUG 247.735714 sec : Taking a 5.00000 seconds frame...
DEBUG 252.738295 sec : GetQHYCCDSingleFrame Blocking read call.
DEBUG 252.738363 sec : QHYCCD|QHYBASE.H|StopRemainingTimesCount
DEBUG 252.738387 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal| #1 readnum,badframenum,ret 0 0 -1
DEBUG 252.738416 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal| #1 flagquit 0
DEBUG 252.738439 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal|Enter While Loop
DEBUG 252.738461 sec : QHYCCD| QHY5.CPP | GetSingleFrame | Begin
DEBUG 252.738479 sec : QHYCCD| QHY5.CPP | GetSingleFrame | pW pH pBpp pChannels 1280 1024 8 1
DEBUG 252.738504 sec : QHYCCD| QHY5.CPP | GetSingleFrame | vendRXD 0x12 (set exposure) 5000
DEBUG 252.805366 sec : QHYCCD| QHY5.CPP | GetSingleFrame | readUSB2B start
DEBUG 252.806049 sec : QHYCCD|QHYCAM.CPP|readUSB2B|readUSB2B p_size=1600200 p_num=1
DEBUG 252.806064 sec : QHYCCD|QHYCAM.CPP|readUSB2B|i=0
DEBUG 257.913193 sec : QHYCCD|QHYCAM.CPP|readUSB2B|Finished
DEBUG 257.913289 sec : QHYCCD| QHY5.CPP | GetSingleFrame | readUSB2B end
DEBUG 257.913663 sec : QHYCCD| QHY5.CPP | GetSingleFrame | roi end
DEBUG 257.914027 sec : QHYCCD| QHY5.CPP | GetSingleFrame | memcpy end
DEBUG 257.914056 sec : QHYCCD| QHY5.CPP | GetSingleFrame | End
DEBUG 257.914077 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal| #2 readnum = 1 badframenum = 0 flagquit = 0
DEBUG 257.914111 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal|ret w h bpp channels 0 1280 1024 8 1
DEBUG 257.914140 sec : QHYCCD|QHYCCD.CPP|GetQHYCCDSingleFrameInternal|END
DEBUG 257.914160 sec : GetQHYCCDSingleFrame Blocking read call complete.
DEBUG 257.914178 sec : Download complete.
WARNING 257.914477 sec : Telescope focal length is missing.
WARNING 257.914523 sec : Telescope aperture is missing.
DEBUG 257.915007 sec : Uploading file. Ext: fits, Size: 1316160, sendImage? Yes, saveImage? No
DEBUG 257.921288 sec : BLOB transfer took 0.00623192 seconds
DEBUG 257.921325 sec : Upload complete