View Full Version : Recovering from low power modes

June 26, 2013, 14:35:48
I am using a DFK 72AUC02-F on a Samsung Slate tablet (I5) and Windows 8

When the tablet is switched off, it is really put in a low power standby mode and my application remains in memory. When the tablet is switched back on, my application is alive but the camera no longer delivers live video. My application "sees" the camera and connects to it but received no frames.

To get the camera delivering frames again I have to close my application and unplug the camera.

What do I have to do to get the camera working correctly after being in a low power state ?


Stefan Geissler
June 26, 2013, 14:50:02
Hello Jerry,

I am afraid, but there is no solution right now, except disconnect an reconnect the camera.

June 27, 2013, 11:00:19
I cannot recover the camera operation by unplugging it. The application detects that the camera is unplugged (DeviceLost event) and starts a timer waiting for the camera to be reconnected. When the camera is back, it reconnects as follows (Index=0):-

Public Sub ConfigDevice(Index As Integer)
If Index = -1 Then Return
ic.Device = ic.Devices(Index)
ic.VideoFormat = "RGB24 (1296x972)[Binning 2x]"
ic.DeviceFrameRate = 5.0
End Sub

This is not enough, for some reason, to get frames running again (after I call LiveStart).

I have found that calling the ShowDeviceSettingsDialog does enable the camera to start running again sometimes, but I do not want to show complex dialogs to the user.

I am also seeing various blue screens doing this:- APC_INDEX_MISMATCH and BAD_POOL_HEADER

I have also just seen ATTEMPTED_WRITE_TO_READONLY_MEMORY (usbcam_2316.sys)

Stefan Geissler
June 27, 2013, 14:03:11
Dear Jerry,

I see, you use driver 2.3.16. Please use the driver 2.4.14 from http://www.theimagingsource.com/en_US/support/downloads/. In the version 2.4 was a change regarding suspend/resume of the device. Maybe this also fixes your issue.

June 27, 2013, 16:37:19
Things are much better with the newer driver and I can resume live capture after standby without having to unplug the camera.

I found a small issue which I think might be a bug

In the following code segment:

For Each dev In ic.Devices
Trace.WriteLine(Array.IndexOf(ic.Devices, dev))

and the trace output is -1 which is a bit unexpected ! I expected 0.